path: root/lib/common_test/doc/src/run_test_chapter.xml

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<!DOCTYPE chapter SYSTEM "chapter.dtd">

<chapter>
  <header>
    <copyright>
      <year>2003</year><year>2016</year>
      <holder>Ericsson AB. All Rights Reserved.</holder>
    </copyright>
    <legalnotice>
      Licensed under the Apache License, Version 2.0 (the "License");
      you may not use this file except in compliance with the License.
      You may obtain a copy of the License at
 
          http://www.apache.org/licenses/LICENSE-2.0

      Unless required by applicable law or agreed to in writing, software
      distributed under the License is distributed on an "AS IS" BASIS,
      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      See the License for the specific language governing permissions and
      limitations under the License.

    </legalnotice>

    <title>Running Tests and Analyzing Results</title>
    <prepared>Peter Andersson, Kenneth Lundin</prepared>
    <docno></docno>
    <date></date>
    <rev></rev>
    <file>run_test_chapter.xml</file>
  </header>

  <section>
    <title>Using the Common Test Framework</title>

    <p>The <c>Common Test</c> framework provides a high-level
    operator interface for testing, providing the following features:</p>

    <list type="bulleted">
	<item>Automatic compilation of test suites (and help modules)</item>
	<item>Creation of extra HTML pages for improved overview.</item>
	<item>Single-command interface for running all available tests</item>
	<item>Handling of configuration files specifying data related to
	  the System Under Test (SUT) (and any other variable data)</item>
	<item>Mode for running multiple independent test sessions in parallel with
	  central control and configuration</item>	
      </list>
  </section>

  <section>
    <title>Automatic Compilation of Test Suites and Help Modules</title>
    <p>When <c>Common Test</c> starts, it automatically attempts to compile any
      suites included in the specified tests. If particular
      suites are specified, only those suites are compiled. If a
      particular test object directory is specified (meaning all suites
      in this directory are to be part of the test), <c>Common Test</c> runs
      function <c>make:all/1</c> in the directory to compile the suites.</p>

    <p>If compilation fails for one or more suites, the compilation errors
      are printed to tty and the operator is asked if the test run is to proceed
      without the missing suites, or be aborted. If the operator chooses to proceed, 
      the tests having missing suites are noted in the HTML log. If <c>Common Test</c> is
      unable to prompt the user after compilation failure (if <c>Common Test</c> does not
      control <c>stdin</c>), the test run proceeds automatically without the missing
      suites. This behavior can however be modified with the
      <c><![CDATA[ct_run]]></c> flag <c><![CDATA[-abort_if_missing_suites]]></c>, 
      or the <seealso marker="ct#run_test-1"><c>ct:run_test/1</c></seealso> option
      <c><![CDATA[{abort_if_missing_suites,TrueOrFalse}]]></c>. If 
      <c><![CDATA[abort_if_missing_suites]]></c> is set to <c>true</c>, the test run
      stops immediately if some suites fail to compile.</p>

    <p>Any help module (that is, regular Erlang module with name not ending with
      "_SUITE") that resides in the same test object directory as a suite, 
      which is part of the test, is also automatically compiled. A help
      module is not mistaken for a test suite (unless it has a "_SUITE" name).
      All help modules in a particular test object directory
      are compiled, no matter if all or only particular suites in the directory 
      are part of the test.</p>

    <p>If test suites or help modules include header files stored in other
      locations than the test directory, these include directories can be specified
      by using flag <c><![CDATA[-include]]></c> with 
      <seealso marker="ct_run"><c>ct_run</c></seealso>, 
      or option <c><![CDATA[include]]></c> with <c><![CDATA[ct:run_test/1]]></c>.
      Also, an include path can be specified with an OS
      environment variable, <c><![CDATA[CT_INCLUDE_PATH]]></c>.</p>
      <p><em>Example (bash):</em></p>

    <p><c>$ export CT_INCLUDE_PATH=~testuser/common_suite_files/include:~testuser/common_lib_files/include</c></p>

    <p><c>Common Test</c> passes all include directories (specified either with flag/option
      <c><![CDATA[include]]></c>, or variable <c><![CDATA[CT_INCLUDE_PATH]]></c>
      , or both, to the compiler.</p>

    <p>Include directories can also be specified in test specifications,
      see <seealso marker="#test_specifications">Test Specifications</seealso>.</p>

    <p>If the user wants to run all test suites for a test object (or an OTP application)
      by specifying only the top directory (for example, with start flag/option <c>dir</c>),
      <c>Common Test</c> primarily looks for test suite modules in a subdirectory named 
      <c>test</c>. If this subdirectory does not exist, the specified top directory
      is assumed to be the test directory, and test suites are read from
      there instead.</p>

    <p>To disable the automatic compilation feature, use flag
      <c><![CDATA[-no_auto_compile]]></c> with <c><![CDATA[ct_run]]></c>, or
      option <c><![CDATA[{auto_compile,false}]]></c> with 
      <c><![CDATA[ct:run_test/1]]></c>. With automatic compilation
      disabled, the user is responsible for compiling the test suite modules 
      (and any help modules) before the test run. If the modules cannot be loaded
      from the local file system during startup of <c>Common Test</c>, the user must
      preload the modules before starting the test. <c>Common Test</c> only verifies
      that the specified test suites exist (that is, that they are, or can be, loaded).
      This is useful, for example, if the test suites are transferred and loaded as 
      binaries through RPC from a remote node.</p>
  </section>

  <section>
  <marker id="ct_run"></marker>
    <title>Running Tests from the OS Command Line</title>
    
    <p>The <seealso marker="ct_run"><c>ct_run</c></seealso> program can be used 
       for running tests from the OS command line, for example, as follows:
    </p>
    <list type="bulleted">
      <item><c><![CDATA[ct_run -config <configfilenames> -dir <dirs>]]></c></item>
      <item><c><![CDATA[ct_run -config <configfilenames> -suite <suiteswithfullpath>]]></c>
      </item>
      <item><c><![CDATA[ct_run -userconfig <callbackmodulename> <configfilenames> -suite <suiteswithfullpath>]]></c>
      </item>
      <item><c><![CDATA[ct_run -config <configfilenames> -suite <suitewithfullpath>
	      -group <groups> -case <casenames>]]></c></item>
    </list>
    <p><em>Examples:</em></p>
    <pre>
 $ ct_run -config $CFGS/sys1.cfg $CFGS/sys2.cfg -dir $SYS1_TEST $SYS2_TEST
 $ ct_run -userconfig ct_config_xml $CFGS/sys1.xml $CFGS/sys2.xml -dir $SYS1_TEST $SYS2_TEST
 $ ct_run -suite $SYS1_TEST/setup_SUITE $SYS2_TEST/config_SUITE
 $ ct_run -suite $SYS1_TEST/setup_SUITE -case start stop
 $ ct_run -suite $SYS1_TEST/setup_SUITE -group installation -case start stop</pre>
    
    <p>The flags <c>dir</c>, <c>suite</c>, and <c>group/case</c> can be combined.
    For example, to run <c>x_SUITE</c> and <c>y_SUITE</c> 
    in directory <c>testdir</c>, as follows:</p>
    <pre>
 $ ct_run -dir ./testdir -suite x_SUITE y_SUITE</pre>

    <p>This has the same effect as the following:</p>
    <pre>
 $ ct_run -suite ./testdir/x_SUITE ./testdir/y_SUITE</pre>

    <p>For details, see 
    <seealso marker="run_test_chapter#group_execution">Test Case Group Execution</seealso>.</p>

    <p>The following flags can also be used with 
    <seealso marker="ct_run"><c>ct_run</c></seealso>:</p>
    <taglist>
      <tag><c><![CDATA[-help]]></c></tag>
      <item><p>Lists all available start flags.</p></item>

      <tag><c><![CDATA[-logdir <dir>]]></c></tag>
      <item><p>Specifies where the HTML log files are to be written.</p></item>

      <tag><c><![CDATA[-label <name_of_test_run>]]></c></tag>
      <item><p>Associates the test run with a name that gets printed
	in the overview HTML log files.</p></item>

      <tag><c>-refresh_logs</c></tag>
      <item><p>Refreshes the top-level HTML index files.</p></item>

      <tag><c>-vts</c></tag>
      <item><p>Starts web-based GUI (described later).</p></item>

      <tag><c>-shell</c></tag>
      <item><p>Starts interactive shell mode (described later).</p></item>

      <tag><c>-step [step_opts]</c></tag>
      <item><p>Steps through test cases using the Erlang Debugger (described later).</p></item>

      <tag><c><![CDATA[-spec <testspecs>]]></c></tag>
      <item><p>Uses test specification as input (described later).</p></item>

      <tag><c>-allow_user_terms</c></tag>
      <item><p>Allows user-specific terms in a test specification (described later).</p></item>

      <tag><c>-silent_connections [conn_types]</c></tag>
      <item><p>, tells <c>Common Test</c> to suppress printouts for
        specified connections (described later).</p></item>

      <tag><c><![CDATA[-stylesheet <css_file>]]></c></tag>
      <item><p>Points out a user HTML style sheet (described later).</p></item>

      <tag><c><![CDATA[-cover <cover_cfg_file>]]></c></tag>
      <item><p>To perform code coverage test (see 
	<seealso marker="cover_chapter#cover">Code Coverage Analysis</seealso>).</p></item>

      <tag><c><![CDATA[-cover_stop <bool>]]></c></tag>
      <item><p>To specify if the <c>cover</c> tool is to be stopped 
      after the test is completed (see
	<seealso marker="cover_chapter#cover_stop">Code Coverage Analysis</seealso>).</p></item>

      <tag><c><![CDATA[-event_handler <event_handlers>]]></c></tag>
      <item><p>To install 
        <seealso marker="event_handler_chapter#event_handling">event handlers</seealso>.</p></item>

      <tag><c><![CDATA[-event_handler_init <event_handlers>]]></c></tag>
      <item><p>To install
        <seealso marker="event_handler_chapter#event_handling">event handlers</seealso> 
      including start arguments.</p></item>

      <tag><c><![CDATA[-ct_hooks <ct_hooks>]]></c></tag>
      <item><p>To install
        <seealso marker="ct_hooks_chapter#installing">Common Test Hooks</seealso> 
      including start arguments.</p></item>

      <tag><c><![CDATA[-enable_builtin_hooks <bool>]]></c></tag>
      <item><p>To enable or disable
        <seealso marker="ct_hooks_chapter#builtin_cths">Built-in Common Test Hooks</seealso>. 
      Default is <c>true</c>.</p></item>

      <tag><c><![CDATA[-include]]></c></tag>
      <item><p>Specifies include directories (described earlier).</p></item>

      <tag><c><![CDATA[-no_auto_compile]]></c></tag>
      <item><p>Disables the automatic test suite compilation feature (described earlier).</p></item>

      <tag><c><![CDATA[-abort_if_missing_suites]]></c></tag>
      <item><p>Aborts the test run if one or more suites fail to compile (described earlier).</p></item>

      <tag><c><![CDATA[-multiply_timetraps <n>]]></c></tag>
      <item><p>Extends <seealso marker="write_test_chapter#timetraps">timetrap
	  time-out</seealso> values.</p></item>

      <tag><c><![CDATA[-scale_timetraps <bool>]]></c></tag>	  
      <item><p>Enables automatic <seealso marker="write_test_chapter#timetraps">timetrap
	  time-out</seealso> scaling.</p></item>

      <tag><c><![CDATA[-repeat <n>]]></c></tag>
      <item><p>Tells <c>Common Test</c> to repeat the tests <c>n</c> times (described later).</p></item> 

      <tag><c><![CDATA[-duration <time>]]></c></tag>
      <item><p>Tells <c>Common Test</c> to repeat the tests for duration of time (described later).</p></item> 

      <tag><c><![CDATA[-until <stop_time>]]></c></tag>
      <item><p>Tells <c>Common Test</c> to repeat the tests until <c>stop_time</c> (described later).</p></item>

      <tag><c>-force_stop [skip_rest]</c></tag>
      <item><p>On time-out, the test run is aborted when the current test job is finished. If <c>skip_rest</c> 
      is provided, the remaining test cases in the current test job are skipped (described later).</p></item>

      <tag><c><![CDATA[-decrypt_key <key>]]></c></tag>
      <item><p>Provides a decryption key for 
      <seealso marker="config_file_chapter#encrypted_config_files">encrypted configuration files</seealso>.</p></item>

      <tag><c><![CDATA[-decrypt_file <key_file>]]></c></tag>
      <item><p>Points out a file containing a decryption key for 
        <seealso marker="config_file_chapter#encrypted_config_files">encrypted configuration files</seealso>.</p></item>

      <tag><c><![CDATA[-basic_html]]></c></tag>
      <item><p>Switches off HTML enhancements that can be incompatible with older browsers.</p></item>

      <tag><c><![CDATA[-logopts <opts>]]></c></tag>
      <item><p>Enables modification of the logging behavior, see
      <seealso marker="run_test_chapter#logopts">Log options</seealso>.</p></item>

      <tag><c><![CDATA[-verbosity <levels>]]></c></tag>
      <item><p>Sets <seealso marker="write_test_chapter#logging">verbosity levels
      for printouts</seealso>.</p></item>

      <tag><c><![CDATA[-no_esc_chars]]></c></tag>
      <item><p>Disables automatic escaping of special HTML characters.
      See the <seealso marker="write_test_chapter#logging">Logging chapter</seealso>.</p></item>
    </taglist>

    <note><p>Directories passed to <c>Common Test</c> can have either relative or absolute paths.</p></note>

    <note><p>Any start flags to the Erlang runtime system (application ERTS) can also be passed as
             parameters to <c>ct_run</c>. It is, for example, useful to be able to
	     pass directories to be added to the Erlang code server search path
	     with flag <c>-pa</c> or <c>-pz</c>. If you have common help- or library 
	     modules for test suites (separately compiled), stored in other directories 
	     than the test suite directories, these <c>help/lib</c> directories are preferably
	     added to the code path this way.</p>
	     <p><em>Example:</em></p>
	  <p><c>$ ct_run -dir ./chat_server -logdir ./chat_server/testlogs -pa $PWD/chat_server/ebin</c></p>
	  <p>The absolute path of directory <c>chat_server/ebin</c>
	     is here passed to the code server. This is essential because relative
	     paths are stored by the code server as relative, and <c>Common Test</c> changes 
	     the current working directory of ERTS during the test run.</p>
    </note>
    
    <p>The <c>ct_run</c> program sets the exit status before shutting down. The following values
      are defined:</p>
    <list type="bulleted">
      <item><c>0</c> indicates a successful testrun, that is, without failed or auto-skipped test cases.</item>
      <item><c>1</c> indicates that one or more test cases have failed, or have been auto-skipped.</item>
      <item><c>2</c> indicates that the test execution has failed because of, for example, compilation errors, or an
	illegal return value from an information function.</item>
    </list>
    <p>If auto-skipped test cases do not affect the exit status. The default
      behavior can be changed using start flag:</p>
    <pre>
 -exit_status ignore_config</pre>
    
    <note><p>Executing <c>ct_run</c> without start flags is equal to the command:
    <c>ct_run -dir ./</c></p></note>

    <p>For more information about the <c>ct_run</c> program, see module
      <seealso marker="ct_run"><c>ct_run</c></seealso> and section
      <seealso marker="install_chapter#general">Installation</seealso>.
    </p>
  </section>
    
  <section>
    <marker id="erlang_shell_or_program"></marker>
    <title>Running Tests from the Erlang Shell or from an Erlang Program</title>
    
    <p><c>Common Test</c> provides an Erlang API for running tests. The main 
      (and most flexible) function for specifying and executing tests is
      <seealso marker="ct#run_test-1"><c>ct:run_test/1</c></seealso>.
      It takes the same start parameters as
      <seealso marker="run_test_chapter#ct_run"><c>ct_run</c></seealso>,
      but the flags are instead specified as options in a list of key-value tuples. 
      For example, a test specified with <c>ct_run</c> as follows:</p>

      <p><c>$ ct_run -suite ./my_SUITE -logdir ./results</c></p> 
      <p>is with <seealso marker="ct#run_test-1"><c>ct:run_test/1</c></seealso> specified as:</p>
      <p><c>1> ct:run_test([{suite,"./my_SUITE"},{logdir,"./results"}]).</c></p>

      <p>The function returns the test result, represented by the tuple
	<c>{Ok,Failed,{UserSkipped,AutoSkipped}}</c>, where each element is an
	integer. If test execution fails, the function returns the tuple
	<c>{error,Reason}</c>, where the term <c>Reason</c> explains the
	failure.</p>

      <p>The default start option <c>{dir,Cwd}</c> (to run all suites in the current
      working directory) is used if the function is called with an empty
      list of options.</p>

	<section>
	  <title>Releasing the Erlang Shell</title>
	  <p>During execution of tests started with
	  <seealso marker="ct#run_test-1"><c>ct:run_test/1</c></seealso>,
	  the Erlang shell process, controlling <c>stdin</c>, remains the top-level
	  process of the <c>Common Test</c> system of processes. Consequently,
	  the Erlang shell is not available for interaction during
	  the test run. If this is not desirable, for example, because the shell 
	  is needed for debugging purposes or for interaction with the SUT during test
	  execution, set start option <c>release_shell</c> to
	  <c>true</c> (in the call to <c>ct:run_test/1</c> or by
	  using the corresponding test specification term, described later). This
	  makes <c>Common Test</c> release the shell immediately after the test suite
	  compilation stage. To accomplish this, a test runner process
	  is spawned to take control of the test execution. The effect is that
	  <c>ct:run_test/1</c> returns the pid of this process rather than the
	  test result, which instead is printed to tty at the end of the test run.</p>
	  <note><p>To use the functions
	  <seealso marker="ct#break-1"><c>ct:break/1,2</c></seealso> and
	  <seealso marker="ct#continue-0"><c>ct:continue/0,1</c></seealso>,
	  <c>release_shell</c> <em>must</em> be set to <c>true</c>.</p></note>
	</section>
        
      <p>For details, see
        <seealso marker="ct#run_test-1"><c>ct:run_test/1</c></seealso> manual page.</p>    
  </section>
  
   <section>
    <marker id="group_execution"></marker>
    <title>Test Case Group Execution</title>
    
    <p>With the <c>ct_run</c> flag, or <c>ct:run_test/1</c> option <c>group</c>,
    one or more test case groups can be specified, optionally in combination
    with specific test cases. The syntax for specifying groups on the command line
    is as follows:</p>

    <pre>
 <![CDATA[$ ct_run -group <group_names_or_paths> [-case <cases>]]]></pre>
    <p>The syntax in the Erlang shell is as follows:</p>
    <pre>
 <![CDATA[1> ct:run_test([{group,GroupsNamesOrPaths}, {case,Cases}]).]]></pre>
    
    <p>Parameter <c>group_names_or_paths</c> specifies one
    or more group names and/or one or more group paths. At startup,
    <c>Common Test</c> searches for matching groups in the group definitions
    tree (that is, the list returned from <c>Suite:groups/0</c>; for details, see section
    <seealso marker="write_test_chapter#test_case_groups">Test Case Groups</seealso>.
    </p>

    <p>Given a group name, say <c>g</c>, <c>Common Test</c> searches for all paths
    leading to <c>g</c>. By path is meant a sequence of nested groups,
    which must be followed to get from the top-level
    group to <c>g</c>. To execute the test cases in group <c>g</c>, 
    <c>Common Test</c> must call the <c>init_per_group/2</c> function for 
    each group in the path to <c>g</c>, and all corresponding <c>end_per_group/2</c>
    functions afterwards. This is because the configuration
    of a test case in <c>g</c> (and its <c>Config</c> input data) depends on
    <c>init_per_testcase(TestCase, Config)</c> and its return value, which
    in turn depends on <c>init_per_group(g, Config)</c> and its return value,
    which in turn depends on <c>init_per_group/2</c> of the group above
    <c>g</c>, and so on, all the way up to the top-level group.</p>

    <p>This means that if there is more than one way to locate a group 
    (and its test cases) in a path, the result of the group search operation 
    is a number of tests, all of which are to be performed.
    <c>Common Test</c> interprets a group specification that consists of a
    single name as follows:</p>

    <p>"Search and find all paths in the group definitions tree that lead
    to the specified group and, for each path, create a test that does the following, 
    in order:</p>
    <list type="ordered">
      <item>Executes all configuration functions in the path to the specified group.</item>
      <item>Executes all, or all matching, test cases in this group.</item>
      <item>Executes all, or all matching, test cases in all subgroups of the group."</item>
    </list>
    
    <p>The user can specify a specific group path with
    parameter <c>group_names_or_paths</c>. With this type of specification
    execution of unwanted groups (in otherwise matching paths),
    and/or the execution of subgroups can be avoided. The command line syntax of the 
    group path is a list of group names in the path, for example:
    </p>
    <p><c>$ ct_run -suite "./x_SUITE" -group [g1,g3,g4] -case tc1 tc5</c></p>
    <p>The syntax in the Erlang shell is as follows (requires a list within the groups list):</p>
    <p><c>1> ct:run_test([{suite,"./x_SUITE"}, {group,[[g1,g3,g4]]}, {testcase,[tc1,tc5]}]).</c></p>
    
    <p>The last group in the specified path is the terminating group in
    the test, that is, no subgroups following this group are executed. In the
    previous example, <c>g4</c> is the terminating group. Hence, <c>Common Test</c>
    executes a test that calls all <c>init</c> configuration functions in the path to
    <c>g4</c>, that is, <c>g1..g3..g4</c>. It then calls test cases <c>tc1</c>
    and <c>tc5</c> in <c>g4</c>, and finally all <c>end</c> configuration functions 
    in order <c>g4..g3..g1</c>.</p>
    
    <note><p>The group path specification does not necessarily
    have to include <em>all</em> groups in the path to the terminating group.
    <c>Common Test</c> searches for all matching paths if an incomplete 
    group path is specified.</p></note>
    
    <note><p>Group names and group paths can be combined with parameter
    <c>group_names_or_paths</c>. Each element is treated as an individual specification 
    in combination with parameter <c>cases</c>.
    The following examples illustrates this.</p></note>   

    <p><em>Examples:</em></p>
    <pre>
 -module(x_SUITE).
 ...
 %% The group definitions:      
 groups() ->
   [{top1,[],[tc11,tc12,
	      {sub11,[],[tc12,tc13]},
	      {sub12,[],[tc14,tc15,
			 {sub121,[],[tc12,tc16]}]}]},

    {top2,[],[{group,sub21},{group,sub22}]},
    {sub21,[],[tc21,{group,sub2X2}]},
    {sub22,[],[{group,sub221},tc21,tc22,{group,sub2X2}]},
    {sub221,[],[tc21,tc23]},
    {sub2X2,[],[tc21,tc24]}].</pre>

    <p>The following executes two tests, one for all cases and all subgroups 
    under <c>top1</c>, and one for all under <c>top2</c>:</p>
    <pre>
 $ ct_run -suite "x_SUITE" -group all
 1> ct:run_test([{suite,"x_SUITE"}, {group,all}]).</pre>
    <p>Using <c>-group top1 top2</c>, or <c>{group,[top1,top2]}</c> gives the same result.</p>

    <p>The following executes one test for all cases and subgroups under <c>top1</c>:</p>
    <pre>
 $ ct_run -suite "x_SUITE" -group top1
 1> ct:run_test([{suite,"x_SUITE"}, {group,[top1]}]).</pre>

    <p>The following runs a test executing <c>tc12</c> in <c>top1</c> and any subgroup
    under <c>top1</c> where it can be found (<c>sub11</c> and <c>sub121</c>):</p>
    <pre>
 $ ct_run -suite "x_SUITE" -group top1 -case tc12
 1> ct:run_test([{suite,"x_SUITE"}, {group,[top1]}, {testcase,[tc12]}]).</pre>

    <p>The following executes <c>tc12</c> <em>only</em> in group <c>top1</c>:</p>
    <pre>
 $ ct_run -suite "x_SUITE" -group [top1] -case tc12
 1> ct:run_test([{suite,"x_SUITE"}, {group,[[top1]]}, {testcase,[tc12]}]).</pre>
    
    <p>The following searches <c>top1</c> and all its subgroups for <c>tc16</c> resulting
    in that this test case executes in group <c>sub121</c>:</p>
    <pre>
 $ ct_run -suite "x_SUITE" -group top1 -case tc16
 1> ct:run_test([{suite,"x_SUITE"}, {group,[top1]}, {testcase,[tc16]}]).</pre>
    <p>Using the specific path <c>-group [sub121]</c> or <c>{group,[[sub121]]}</c> gives
    the same result in this example.</p>

    <p>The following executes two tests, one including all cases and subgroups under
    <c>sub12</c>, and one with <em>only</em> the test cases in <c>sub12</c>:</p>
    <pre>
 $ ct_run -suite "x_SUITE" -group sub12 [sub12]
 1> ct:run_test([{suite,"x_SUITE"}, {group,[sub12,[sub12]]}]).</pre>

    <p>In the following example, <c>Common Test</c> finds and executes two tests, 
    one for the path from <c>top2</c> to <c>sub2X2</c> through <c>sub21</c>, 
    and one from <c>top2</c> to <c>sub2X2</c> through <c>sub22</c>:</p>
    <pre>
 $ ct_run -suite "x_SUITE" -group sub2X2
 1> ct:run_test([{suite,"x_SUITE"}, {group,[sub2X2]}]).</pre>

    <p>In the following example, by specifying the unique path <c>top2 -> sub21 -> sub2X2</c>, 
    only one test is executed. The second possible path, from <c>top2</c> to <c>sub2X2</c> 
    (from the former example) is discarded:</p>
    <pre>
 $ ct_run -suite "x_SUITE" -group [sub21,sub2X2]
 1> ct:run_test([{suite,"x_SUITE"}, {group,[[sub21,sub2X2]]}]).</pre>

    <p>The following executes only the test cases for <c>sub22</c> and in reverse order 
    compared to the group definition:</p>
    <pre>
 $ ct_run -suite "x_SUITE" -group [sub22] -case tc22 tc21
 1> ct:run_test([{suite,"x_SUITE"}, {group,[[sub22]]}, {testcase,[tc22,tc21]}]).</pre>

    <p>If a test case belonging to a group (according to the group definition) is executed
    without a group specification, that is, simply by
    (using the command line):</p>
    <p><c>$ ct_run -suite "my_SUITE" -case my_tc</c></p>
    <p>or (using the Erlang shell):</p>
    <p><c>1> ct:run_test([{suite,"my_SUITE"}, {testcase,my_tc}]).</c></p>
    <p>then <c>Common Test</c> ignores the group definition and executes the test case 
    in the scope of the test suite only (no group configuration functions are called).</p>

    <p>The group specification feature, as presented in this section, can also
    be used in <seealso marker="run_test_chapter#test_specifications">Test
    Specifications</seealso> (with some extra features added).</p>
   </section>
      

  <section>
    <title>Running the Interactive Shell Mode</title>
    
    <p>You can start <c>Common Test</c> in an interactive shell mode where no
      automatic testing is performed. Instead, <c>Common Test</c>
      starts its utility processes, installs configuration data (if any),
      and waits for the user to call functions (typically test case support
      functions) from the Erlang shell.</p>

    <p>The shell mode is useful, for example, for debugging test suites, analyzing
      and debugging the SUT during "simulated" test case execution, and 
      trying out various operations during test suite development.</p>

    <p>To start the interactive shell mode, start an Erlang shell 
      manually and call <seealso marker="ct#install-1"><c>ct:install/1</c></seealso> 
      to install any configuration data you might need (use <c>[]</c> as argument otherwise). 
      Then call <seealso marker="ct#start_interactive-0"><c>ct:start_interactive/0</c></seealso> 
      to start <c>Common Test</c>.</p>
      
      <p>If you use the <c>ct_run</c> program, you can start 
      the Erlang shell and <c>Common Test</c> in one go by using the flag <c>-shell</c> and, 
      optionally, flag <c>-config</c> and/or <c>-userconfig</c>.</p>
      <p><em>Examples:</em></p>
    <list type="bulleted">
      <item><c>ct_run -shell</c></item>
      <item><c><![CDATA[ct_run -shell -config cfg/db.cfg]]></c></item>
      <item><c><![CDATA[ct_run -shell -userconfig db_login testuser x523qZ]]></c></item>
    </list>
    
    <p>If no configuration file is specified with command <c>ct_run</c>,
      a warning is displayed. If <c>Common Test</c> has been run from the same
      directory earlier, the same configuration file(s) are used again. If <c>Common Test</c> 
      has not been run from this directory before, no configuration files are available.</p>
    
    <p>If any functions using "required configuration data" (for example, functions 
      <c>ct_telnet</c> or <c>ct_ftp</c>) are to be called from the Erlang shell, first require 
      configuration data with <seealso marker="ct#require-1"><c>
      ct:require/1,2</c></seealso>. This is equivalent to a <c>require</c> statement 
      in the <seealso marker="write_test_chapter#suite">Test Suite Information Function</seealso> 
      or in the <seealso marker="write_test_chapter#info_function">Test Case Information Function</seealso>.</p>
      
    <p><em>Example:</em></p>
    <pre> 
 1> ct:require(unix_telnet, unix).
 ok
 2> ct_telnet:open(unix_telnet).
 {ok,&lt;0.105.0&gt;}
 4> ct_telnet:cmd(unix_telnet, "ls .").
 {ok,["ls .","file1  ...",...]}</pre>
    
    <p>Everything that <c>Common Test</c> normally prints in the test case logs,
      are in the interactive mode written to a log named <c>ctlog.html</c> 
      in directory  <c><![CDATA[ct_run.<timestamp>]]></c>. A link to this 
      file is available in the file named <c>last_interactive.html</c> in the 
      directory from which you execute <c>ct_run</c>. Specifying a different
      root directory for the logs than the current working directory
      is not supported.</p>
    
    <p>If you wish to exit the interactive mode (for example, to start an automated 
      test run with <seealso marker="ct#run_test-1"><c>ct:run_test/1</c></seealso>), 
      call function
      <seealso marker="ct#stop_interactive-0"><c>ct:stop_interactive/0</c></seealso>. 
      This shuts down the running <c>ct</c> application. Associations between
      configuration names and data created with <c>require</c> are 
      consequently deleted. Function
      <seealso marker="ct#start_interactive-0"><c>ct:start_interactive/0</c></seealso> 
      takes you back into interactive mode, but the previous state is not restored.</p>
  </section>

  <section>
    <title>Step-by-Step Execution of Test Cases with the Erlang Debugger</title>
   
    <p>Using <c>ct_run -step [opts]</c>, or by passing option <c>{step,Opts}</c> 
       to <seealso marker="ct#run_test-1"><c>ct:run_test/1</c></seealso>, 
       the following is possible:</p>
       <list type="bulleted">
       <item>Get the Erlang Debugger started automatically.</item>
       <item>Use its graphical interface to investigate the state of the current test case.</item>
       <item>Execute the test case step-by-step and/or set execution breakpoints.</item>
     </list>
    <p>If no extra options are specified with flag/option <c>step</c>,
       breakpoints are set automatically on the test cases that
       are to be executed by <c>Common Test</c>, and those functions only. If
       step option <c>config</c> is specified, breakpoints are also initially 
       set on the configuration functions in the suite, that is,
       <c>init_per_suite/1</c>, <c>end_per_suite/1</c>,
       <c>init_per_group/2</c>, <c>end_per_group/2</c>,
       <c>init_per_testcase/2</c> and <c>end_per_testcase/2</c>.</p>
    <p><c>Common Test</c> enables the Debugger auto-attach feature, which means
       that for every new interpreted test case function that starts to execute, 
       a new trace window automatically pops up (as each test 
       case executes on a dedicated Erlang process). Whenever a new test case starts,
       <c>Common Test</c> attempts to close the inactive trace window of the previous 
       test case. However, if you prefer <c>Common Test</c> to leave inactive trace 
       windows, use option <c>keep_inactive</c>.</p>
    <p>The step functionality can be used together with flag/option <c>suite</c> and 
       <c>suite</c> + <c>case/testcase</c>, but not together with <c>dir</c>.</p>       
  </section>

  <section>
  <marker id="test_specifications"></marker>
    <title>Test Specifications</title>
    <section>
	<title>General Description</title>
	<p>The most flexible way to specify what to test, is to use a
	test specification, which is a sequence of
	Erlang terms. The terms are normally declared in one or more text files
	(see <seealso marker="ct#run_test-1"><c>ct:run_test/1</c></seealso>), but
	can also be passed to <c>Common Test</c> on the form of a list (see
	<seealso marker="ct#run_testspec-1"><c>ct:run_testspec/1</c></seealso>).
	There are two general types of terms: configuration terms and test
	specification terms.</p>

	<p>With configuration terms it is, for example, possible to do the following:</p>
	<list type="bulleted">
       <item>Label the test run (similar to <c>ct_run -label</c>).</item>
       <item>Evaluate any expressions before starting the test.</item>
       <item>Import configuration data (similar to <c>ct_run -config/-userconfig</c>).</item>
       <item>Specify the top-level HTML log directory (similar to <c>ct_run -logdir</c>).</item>
       <item>Enable code coverage analysis (similar to <c>ct_run -cover</c>).</item>
       <item>Install <c>Common Test Hooks</c> (similar to <c>ct_run -ch_hooks</c>).</item>
       <item>Install <c>event_handler</c> plugins (similar to <c>ct_run -event_handler</c>).</item>
       <item>Specify include directories to be passed to the compiler for 
       automatic compilation (similar to <c>ct_run -include</c>).</item>
       <item>Disable the auto-compilation feature (similar to <c>ct_run -no_auto_compile</c>).</item>
       <item>Set verbosity levels (similar to <c>ct_run -verbosity</c>).</item>
     </list>

	<p>Configuration terms can be combined with <c>ct_run</c> start flags
	or <c>ct:run_test/1</c> options. The result is, for some flags/options
	and terms, that the values are merged (for example, configuration files,
	include directories, verbosity levels, and silent connections) and for
	others that the start flags/options override the test specification
	terms (for example, log directory, label, style sheet, and auto-compilation).</p>

	<p>With test specification terms, it is possible to state exactly
	which tests to run and in which order. A test term specifies
	either one or more suites, one or more test case groups (possibly nested),
	or one or more test cases in a group (or in multiple groups) or in a suite.</p>

	<p>Any number of test terms can be declared in sequence.
	<c>Common Test</c> compiles by default the terms into one or more tests 
	to be performed in one resulting test run. A term that
	specifies a set of test cases "swallows" one that only
	specifies a subset of these cases. For example, the result of merging
	one term specifying that all cases in suite S are to be
	executed, with another term specifying only test case X and Y in
	S, is a test of all cases in S. However, if a term specifying
	test case X and Y in S is merged with a term specifying case Z
	in S, the result is a test of X, Y, and Z in S. To disable this
	behavior, that is, to instead perform each test sequentially in a 
	"script-like" manner, set term <c>merge_tests</c> to <c>false</c> 
	in the test specification.</p>

	<p>A test term can also specify one or more test suites, groups,
	or test cases to be skipped. Skipped suites, groups, and cases
	are not executed and show up in the HTML log files as <c>SKIPPED</c>.</p>
    </section>
    <section>
        <title>Using Multiple Test Specification Files</title>
	
	<p>When multiple test specification files are specified at startup (either
	with <c>ct_run -spec file1 file2 ...</c> or 
	<c>ct:run_test([{spec, [File1,File2,...]}])</c>), 
	<c>Common Test</c> either executes one test run per specification file, 
	or joins the files and performs all tests within one single test run. 
	The first behavior is the default one. The latter requires that start
	flag/option <c>join_specs</c> is provided, for example,
	<c>run_test -spec ./my_tests1.ts ./my_tests2.ts -join_specs</c>.</p>
	
	<p>Joining a number of specifications, or running them separately, can
	also be accomplished with (and can be combined with) test specification
	file inclusion.</p>
    </section>
    <section>
      <title>Test Specification File Inclusion</title>
        <p>With the term <c>specs</c>, a test specification can include 
	other specifications. An included specification can either be joined 
	with the source specification or used to produce a separate test run 
	(as with start flag/option <c>join_specs</c> above).</p>
	<p><em>Example:</em></p>

	<pre>
 %% In specification file "a.spec"
 {specs, join, ["b.spec", "c.spec"]}.
 {specs, separate, ["d.spec", "e.spec"]}.
 %% Config and test terms follow
 ...</pre>

	<p>In this example, the test terms defined in files "b.spec" and "c.spec"
	are joined with the terms in source specification "a.spec"
	(if any). The inclusion of specifications "d.spec" and
	"e.spec" results in two separate, and independent, test runs
	(one for each included specification).</p>

	<p>Option <c>join</c> does not imply that the test terms
	are merged, only that all tests are executed in one single test run.</p>

	<p>Joined specifications share common configuration settings, such as
	the list of <c>config</c> files or <c>include</c> directories.
	For configurations that cannot be combined, such as settings for <c>logdir</c>
	or <c>verbosity</c>, it is up to the user to ensure there are no clashes
	when the test specifications are joined. Specifications included with
	option <c>separate</c> do not share configuration settings with the
	source specification. This is useful, for example, if there are clashing
	configuration settings in included specifications, making it them impossible
	to join.</p>

	<p>If <c>{merge_tests,true}</c> is set in the source specification
	(which is the default setting), terms in joined specifications are
	merged with terms in the source specification (according to the
	description of <c>merge_tests</c> earlier).</p>

	<p>Notice that it is always the <c>merge_tests</c> setting in the source
	specification that is used when joined with other specifications.
	Say, for example, that a source specification A, with tests TA1 and TA2, has
	<c>{merge_tests,false}</c> set, and that it includes another specification,
	B, with tests TB1 and TB2, that has <c>{merge_tests,true}</c> set.
	The result is that the test series <c>TA1,TA2,merge(TB1,TB2)</c>
	is executed. The opposite <c>merge_tests</c> settings would result in
	the test series <c>merge(merge(TA1,TA2),TB1,TB2)</c>.</p>

	<p>The term <c>specs</c> can be used to nest specifications,
	that is, have one specification include other specifications, which in turn
	include others, and so no</p>
    </section>
      <section>
	<title>Test Case Groups</title>

	<p>When a test case group is specified, the resulting test
	executes function <c>init_per_group</c>, followed by all test
	cases and subgroups (including their configuration functions), and
	finally function <c>end_per_group</c>. Also, if particular
	test cases in a group are specified, <c>init_per_group</c>
	and <c>end_per_group</c>, for the group in question, are
	called. If a group defined (in <c>Suite:group/0</c>) as
	a subgroup of another group, is specified (or if particular test
	cases of a subgroup are), <c>Common Test</c> calls the configuration
	functions for the top-level groups and for the subgroup
	in question (making it possible to pass configuration data all
	the way from <c>init_per_suite</c> down to the test cases in the
	subgroup).</p>

	<p>The test specification uses the same mechanism for specifying
	test case groups through names and paths, as explained in section
	<seealso marker="run_test_chapter#group_execution">Test Case Group Execution</seealso>,
	with the addition of element <c>GroupSpec</c>.</p>

	<p>Element <c>GroupSpec</c> makes it possible to specify
	group execution properties that overrides those in the
	group definition (that is, in <c>groups/0</c>). Execution properties for
	subgroups might be overridden as well. This feature makes it possible to
	change properties of groups at the time of execution,
	without having to edit the test suite. The same feature is available for 
	<c>group</c> elements in the <c>Suite:all/0</c> list. For details and examples,
	see section <seealso marker="write_test_chapter#test_case_groups">
	Test Case Groups</seealso>.</p>
      </section>

      <section>
	<title>Test Specification Syntax</title>

	<p>Test specifications can be used to run tests both in a single 
	test host environment and in a distributed <c>Common Test</c> environment 
	(Large Scale Testing). The node parameters in term <c>init</c> are only
	relevant in the latter (see section
	<seealso marker="ct_master_chapter#test_specifications">Test Specifications</seealso> 
	in Large Scale Testing). For details about the various terms, see the 
	corresponding sections in the User's Guide, for example, the following:
	</p>
	<list type="bulleted">
       <item>The <seealso marker="run_test_chapter#ct_run"><c>ct_run</c>
	program</seealso> for an overview of available start flags
	(as most flags have a corresponding configuration term)</item>
       <item><seealso marker="write_test_chapter#logging">Logging</seealso>
	(for terms <c>verbosity</c>, <c>stylesheet</c>, <c>basic_html</c> and <c>esc_chars</c>)</item>
       <item><seealso marker="config_file_chapter#top">External Configuration Data</seealso>
	(for terms <c>config</c> and <c>userconfig</c>)</item>
       <item><seealso marker="event_handler_chapter#event_handling">Event
	Handling</seealso> (for the <c>event_handler</c> term)</item>
       <item><seealso marker="ct_hooks_chapter#installing">Common Test Hooks</seealso>
	(for term <c>ct_hooks</c>)</item>
	</list>

      <p><em>Configuration terms:</em></p>
      <pre>
 {merge_tests, Bool}.

 {define, Constant, Value}.

 {specs, InclSpecsOption, TestSpecs}.

 {node, NodeAlias, Node}.

 {init, InitOptions}.
 {init, [NodeAlias], InitOptions}.

 {label, Label}.
 {label, NodeRefs, Label}.

 {verbosity, VerbosityLevels}.
 {verbosity, NodeRefs, VerbosityLevels}.

 {stylesheet, CSSFile}.
 {stylesheet, NodeRefs, CSSFile}.

 {silent_connections, ConnTypes}.
 {silent_connections, NodeRefs, ConnTypes}.

 {multiply_timetraps, N}.
 {multiply_timetraps, NodeRefs, N}.

 {scale_timetraps, Bool}.
 {scale_timetraps, NodeRefs, Bool}.

 {cover, CoverSpecFile}.
 {cover, NodeRefs, CoverSpecFile}.

 {cover_stop, Bool}.
 {cover_stop, NodeRefs, Bool}.

 {include, IncludeDirs}.
 {include, NodeRefs, IncludeDirs}.

 {auto_compile, Bool},
 {auto_compile, NodeRefs, Bool},

 {abort_if_missing_suites, Bool},
 {abort_if_missing_suites, NodeRefs, Bool},

 {config, ConfigFiles}.
 {config, ConfigDir, ConfigBaseNames}.
 {config, NodeRefs, ConfigFiles}.
 {config, NodeRefs, ConfigDir, ConfigBaseNames}.

 {userconfig, {CallbackModule, ConfigStrings}}.
 {userconfig, NodeRefs, {CallbackModule, ConfigStrings}}.

 {logdir, LogDir}.                                        
 {logdir, NodeRefs, LogDir}.

 {logopts, LogOpts}.
 {logopts, NodeRefs, LogOpts}.

 {create_priv_dir, PrivDirOption}.
 {create_priv_dir, NodeRefs, PrivDirOption}.

 {event_handler, EventHandlers}.
 {event_handler, NodeRefs, EventHandlers}.
 {event_handler, EventHandlers, InitArgs}.
 {event_handler, NodeRefs, EventHandlers, InitArgs}.

 {ct_hooks, CTHModules}.
 {ct_hooks, NodeRefs, CTHModules}.

 {enable_builtin_hooks, Bool}.

 {basic_html, Bool}.
 {basic_html, NodeRefs, Bool}.

 {esc_chars, Bool}.
 {esc_chars, NodeRefs, Bool}.

 {release_shell, Bool}.</pre>
	
      <p><em>Test terms:</em></p>
      <pre>
 {suites, Dir, Suites}.                                
 {suites, NodeRefs, Dir, Suites}.

 {groups, Dir, Suite, Groups}.
 {groups, NodeRefs, Dir, Suite, Groups}.

 {groups, Dir, Suite, Groups, {cases,Cases}}.
 {groups, NodeRefs, Dir, Suite, Groups, {cases,Cases}}.

 {cases, Dir, Suite, Cases}.                           
 {cases, NodeRefs, Dir, Suite, Cases}.

 {skip_suites, Dir, Suites, Comment}.
 {skip_suites, NodeRefs, Dir, Suites, Comment}.

 {skip_groups, Dir, Suite, GroupNames, Comment}.
 {skip_groups, NodeRefs, Dir, Suite, GroupNames, Comment}.

 {skip_cases, Dir, Suite, Cases, Comment}.
 {skip_cases, NodeRefs, Dir, Suite, Cases, Comment}.</pre>

	<marker id="types"></marker>
      <p><em>Types:</em></p>
      <pre>
 Bool            = true | false
 Constant        = atom()
 Value           = term()
 InclSpecsOption = join | separate
 TestSpecs       = string() | [string()]
 NodeAlias       = atom()
 Node            = node()
 NodeRef         = NodeAlias | Node | master
 NodeRefs        = all_nodes | [NodeRef] | NodeRef
 InitOptions     = term()
 Label           = atom() | string()
 VerbosityLevels = integer() | [{Category,integer()}]
 Category        = atom()
 CSSFile         = string()
 ConnTypes       = all | [atom()]
 N               = integer()
 CoverSpecFile   = string()
 IncludeDirs     = string() | [string()]
 ConfigFiles     = string() | [string()]
 ConfigDir       = string()
 ConfigBaseNames = string() | [string()]
 CallbackModule  = atom()
 ConfigStrings   = string() | [string()]
 LogDir          = string()
 LogOpts         = [term()]
 PrivDirOption   = auto_per_run | auto_per_tc | manual_per_tc
 EventHandlers   = atom() | [atom()]
 InitArgs        = [term()]
 CTHModules      = [CTHModule |
		    {CTHModule, CTHInitArgs} |
		    {CTHModule, CTHInitArgs, CTHPriority}]
 CTHModule       = atom()
 CTHInitArgs     = term()
 Dir             = string()
 Suites          = atom() | [atom()] | all
 Suite           = atom()
 Groups          = GroupPath | [GroupPath] | GroupSpec | [GroupSpec] | all
 GroupPath       = [GroupName]
 GroupSpec       = GroupName | {GroupName,Properties} | {GroupName,Properties,GroupSpec}
 GroupName       = atom()
 GroupNames      = GroupName | [GroupName]
 Cases           = atom() | [atom()] | all
 Comment         = string() | ""</pre>
	
	<p>The difference between the <c>config</c> terms above is that with
	<c>ConfigDir</c>, <c>ConfigBaseNames</c> is a list of base names,
	that is, without directory paths. <c>ConfigFiles</c> must be full names,
	including paths. For example, the following two terms have the same meaning:</p>
	<pre>
 {config, ["/home/testuser/tests/config/nodeA.cfg",
           "/home/testuser/tests/config/nodeB.cfg"]}.

 {config, "/home/testuser/tests/config", ["nodeA.cfg","nodeB.cfg"]}.</pre>

	  <note><p>Any relative paths, specified in the test specification, are
	  relative to the directory containing the test specification file if
	  <c>ct_run -spec TestSpecFile ...</c> or
	  <c>ct:run:test([{spec,TestSpecFile},...])</c>
	  executes the test.</p>
	  <p>The path is relative to the top-level log directory if
	  <c>ct:run:testspec(TestSpec)</c> executes the test.</p></note>	  
	</section>

	<section>
	  <title>Constants</title>

	  <p>The term <c>define</c> introduces a constant that is used to
	  replace the name <c>Constant</c> with <c>Value</c>, wherever it is found in
	  the test specification. This replacement occurs during an initial iteration
	  through the test specification. Constants can be used anywhere in the test
	  specification, for example, in any lists and tuples, and even in strings
	  and inside the value part of other constant definitions. A constant can
	  also be part of a node name, but that is the only place where a constant
	  can be part of an atom.</p>
	  
	  <note><p>For the sake of readability, the name of the constant must always
	  begin with an uppercase letter, or a <c>$</c>, <c>?</c>, or <c>_</c>.
	  This means that it must always be single quoted (as the constant name is 
	  an atom, not text).</p></note>
	  
	  <p>The main benefit of constants is that they can be used to reduce the size
	  (and avoid repetition) of long strings, such as file paths.</p>
	  <p><em>Examples:</em></p>
	  
	  <pre>
 %% 1a. no constant
 {config, "/home/testuser/tests/config", ["nodeA.cfg","nodeB.cfg"]}.
 {suites, "/home/testuser/tests/suites", all}.

 %% 1b. with constant
 {define, 'TESTDIR', "/home/testuser/tests"}.
 {config, "'TESTDIR'/config", ["nodeA.cfg","nodeB.cfg"]}.
 {suites, "'TESTDIR'/suites", all}.

 %% 2a. no constants
 {config, [testnode@host1, testnode@host2], "../config", ["nodeA.cfg","nodeB.cfg"]}.
 {suites, [testnode@host1, testnode@host2], "../suites", [x_SUITE, y_SUITE]}.

 %% 2b. with constants
 {define, 'NODE', testnode}.
 {define, 'NODES', ['NODE'@host1, 'NODE'@host2]}.
 {config, 'NODES', "../config", ["nodeA.cfg","nodeB.cfg"]}.
 {suites, 'NODES', "../suites", [x_SUITE, y_SUITE]}.</pre>

	    <p>Constants make the test specification term <c>alias</c>, in previous
	    versions of <c>Common Test</c>, redundant. This term is deprecated but
	    remains supported in upcoming <c>Common Test</c> releases. Replacing <c>alias</c>
	    terms with <c>define</c> is strongly recommended though. An example
	    of such replacement follows:</p>
	    
	    <pre>
 %% using the old alias term
 {config, "/home/testuser/tests/config/nodeA.cfg"}.
 {alias, suite_dir, "/home/testuser/tests/suites"}.
 {groups, suite_dir, x_SUITE, group1}.

 %% replacing with constants
 {define, 'TestDir', "/home/testuser/tests"}.
 {define, 'CfgDir', "'TestDir'/config"}.
 {define, 'SuiteDir', "'TestDir'/suites"}.
 {config, 'CfgDir', "nodeA.cfg"}.
 {groups, 'SuiteDir', x_SUITE, group1}.</pre>
	      
	      <p>Constants can well replace term <c>node</c> also, but
	      this still has a declarative value, mainly when used in combination
	      with <c>NodeRefs == all_nodes</c> 
	      (see <seealso marker="#types">Types</seealso>).</p>
	</section>

	<section>
	  <title>Example</title>
	  
	  <p>Here follows a simple test specification example:</p>
	  <pre>
 {define, 'Top', "/home/test"}.
 {define, 'T1', "'Top'/t1"}.
 {define, 'T2', "'Top'/t2"}.
 {define, 'T3', "'Top'/t3"}.
 {define, 'CfgFile', "config.cfg"}.

 {logdir, "'Top'/logs"}.

 {config, ["'T1'/'CfgFile'", "'T2'/'CfgFile'", "'T3'/'CfgFile'"]}.

 {suites, 'T1', all}.
 {skip_suites, 'T1', [t1B_SUITE,t1D_SUITE], "Not implemented"}.
 {skip_cases, 'T1', t1A_SUITE, [test3,test4], "Irrelevant"}.
 {skip_cases, 'T1', t1C_SUITE, [test1], "Ignore"}.

 {suites, 'T2', [t2B_SUITE,t2C_SUITE]}.
 {cases, 'T2', t2A_SUITE, [test4,test1,test7]}.

 {skip_suites, 'T3', all, "Not implemented"}.</pre>
	  
	  <p>The example specifies the following:</p>
	  <list type="bulleted">
	    <item>The specified <c>logdir</c> directory is used for storing 
	    the HTML log files (in subdirectories tagged with node name, 
	    date, and time).</item>
	    <item>The variables in the specified test system configuration files are
	    imported for the test.</item>
	    <item>The first test to run includes all suites for system <c>t1</c>. 
	    Suites <c>t1B</c> and <c>t1D</c> are excluded from the test. Test cases 
	    <c>test3</c> and <c>test4</c> in <c>t1A</c> and <c>test1</c> case in <c>t1C</c> 
	    are also excluded from the test.</item>
	    <item>The second test to run is for system <c>t2</c>. The included suites are
	    <c>t2B</c> and <c>t2C</c>. Test cases <c>test4</c>, <c>test1</c>, and <c>test7</c> in suite
	    <c>t2A</c> are also included. The test cases are executed in the specified order.</item>
	    <item>The last test to run is for system <c>t3</c>. Here, all suites are skipped and this
	    is explicitly noted in the log files.</item>
	  </list>
	</section>

	<section>
	  <title>The init Term</title>
	  <p>With term <c>init</c> it is possible to specify initialization options
	  for nodes defined in the test specification. There are options
	  to start the node and to evaluate any function on the node.
	  For details, see section <seealso marker="ct_master_chapter#ct_slave">Automatic Startup of
	  Test Target Nodes</seealso> in section Using Common Test for Large Scale Testing.</p>
	</section>
	<section>
	  <title>User-Specific Terms</title>
	  <p>The user can provide a test specification including (for <c>Common Test</c>) 
	  unrecognizable terms. If this is desired, use flag <c>-allow_user_terms</c> 
	  when starting tests with <c>ct_run</c>. This forces <c>Common Test</c> to ignore 
	  unrecognizable terms. In this mode, <c>Common Test</c> is not able to check the 
	  specification for errors as efficiently as if the scanner runs in default mode. 
	  If <seealso marker="ct#run_test-1"><c>ct:run_test/1</c></seealso> is used
	  for starting the tests, the relaxed scanner mode is enabled by tuple
	  <c>{allow_user_terms,true}</c>.</p>
	</section>
	<section>
	  <title>Reading Test Specification Terms</title>
	  <p>Terms in the current test specification
	  (that is, the specification that has been used to configure and run the current test)
	  can be looked up.
	  The function <seealso marker="ct#get_testspec_terms-0"><c>get_testspec_terms()</c></seealso> 
	  returns a list of all test specification terms (both configuration terms and test terms), 
	  and <c>get_testspec_terms(Tags)</c> returns the term (or a list of terms) matching the 
	  tag (or tags) in <c>Tags</c>.</p>
	  <p>For example, in the test specification:</p>
	  <pre>
 ...
 {label, my_server_smoke_test}.
 {config, "../../my_server_setup.cfg"}.
 {config, "../../my_server_interface.cfg"}.
 ...</pre>	    
	  <p>And in, for example, a test suite or a <c>Common Test Hook</c> function:</p>
	  <pre>
 ...
 [{label,[{_Node,TestType}]}, {config,CfgFiles}] =
     ct:get_testspec_terms([label,config]),

 [verify_my_server_cfg(TestType, CfgFile) || {Node,CfgFile} &lt;- CfgFiles,
					     Node == node()];
 ...</pre>
	</section>
  </section>

  <section>
    <title>Running Tests from the Web-Based GUI</title>
    
    <p>The web-based GUI, Virtual Test Server (VTS), is started with the
      <seealso marker="run_test_chapter#ct_run"><c>ct_run</c></seealso>
      program. From the GUI, you can load configuration files and select
      directories, suites, and cases to run. You can also state the
      configuration files, directories, suites, and cases on the command line
      when starting the web-based GUI.
    </p>
    <p><em>Examples:</em></p>
    <list type="bulleted">
      <item><c>ct_run -vts</c></item>
      <item><c><![CDATA[ct_run -vts -config <configfilename>]]></c></item>
      <item><c><![CDATA[ct_run -vts -config <configfilename> -suite <suitewithfullpath>
	      -case <casename>]]></c></item>
    </list>
    
    <p>From the GUI you can run tests and view the result and the logs.
    </p>
    
    <p><c>ct_run -vts</c> tries to open the <c>Common Test</c> start
      page in an existing web browser window, or start the browser if it is
      not running. Which browser to start can be specified with
      the browser start command option:</p>
      <p><c><![CDATA[ct_run -vts -browser <browser_start_cmd>]]></c></p>
      <p><em>Example:</em></p>
      <p><c><![CDATA[$ ct_run -vts -browser 'firefox&']]></c></p>

      <note><p>The browser must run as a separate OS process, otherwise VTS hangs.</p></note>

      <p>If no specific browser start command is specified, Firefox is
        the default browser on Unix platforms, and Internet Explorer on Windows.
	If <c>Common Test</c> fails to start a browser automatically, or <c>none</c> is
	specified as the value for <c>-browser</c> (that is, <c>-browser none</c>), start your
	favourite browser manually and type the URL that <c>Common Test</c>
	displays in the shell.</p>    
  </section>
  
  <section>
    <marker id="log_files"></marker>
    <title>Log Files</title>
    
    <p>As the execution of the test suites proceed, events are logged in
      the following four different ways:</p>
      
      <list type="bulleted">
	<item>Text to the operator console.</item>
	<item>Suite-related information is sent to the major log file.</item>
	<item>Case-related information is sent to the minor log file.</item>
	<item>The HTML overview log file is updated with test results.</item>
	<item>A link to all runs executed from a certain directory is written in
	  the log named <c>all_runs.html</c> and direct links to all tests (the
	  latest results) are written to the top-level <c>index.html</c>.</item>
      </list>
      
      <p>Typically the operator, possibly running hundreds or thousands of
	test cases, does not want to fill the console with details
	about, or printouts from, specific test cases. By default, the 
	operator only sees the following:</p>
      
      <list type="bulleted">
	<item>A confirmation that the test has started and information about how 
	  many test cases are executed in total.</item>
	<item>A small note about each failed test case.</item>
	<item>A summary of all the run test cases.</item>
	<item>A confirmation when the test run is complete.</item>
	<item>Some special information, such as error reports, progress
	  reports, and printouts written with <c>erlang:display/1</c>, or <c>io:format/3</c>
	  specifically addressed to a receiver other than <c>standard_io</c>
	  (for example, the default group leader process <c>user</c>).</item>
      </list>

      <p>To dig deeper into the general results, or
        the result of a specific test case, the operator can do so by
	following the links in the HTML presentation and read the
	major or minor log files. The "all_runs.html" page is a good
	starting point. It is located in <c>logdir</c> and contains
	a link to each test run, including a quick overview (with date and time,
	node name, number of tests, test names, and test result totals).</p>
	
      <p>An "index.html" page is written for each test run (that is, stored in
	the <c>ct_run</c> directory tagged with node name, date, and time). This
	file provides an overview of all individual tests performed in the 
	same test run. The test names follow the following convention:</p>
      <list type="bulleted">
	<item><c>TopLevelDir.TestDir</c> (all suites in <c>TestDir</c> executed)</item>
	<item><c>TopLevelDir.TestDir:suites</c> (specific suites executed)</item>
	<item><c>TopLevelDir.TestDir.Suite</c> (all cases in <c>Suite</c> executed)</item>
	<item><c>TopLevelDir.TestDir.Suite:cases</c> (specific test cases executed)</item>
	<item><c>TopLevelDir.TestDir.Suite.Case</c> (only <c>Case</c> executed)</item>
      </list>
      
      <p>The "test run index" page includes a link to the <c>Common Test</c>
        Framework Log file in which information about imported
        configuration data and general test progress is written. This
        log file is useful to get snapshot information about the test
        run during execution. It can also be helpful when
        analyzing test results or debugging test suites.</p>

      <p>The "test run index" page indicates if a test has missing
        suites (that is, suites that <c>Common Test</c> failed to
        compile). Names of the missing suites can be found in the
        <c>Common Test</c> Framework Log file.</p>

      <p>The major log file shows a detailed report of the test run. It
        includes test suite and test case names, execution time, the 
	exact reason for failures, and so on. The information is available in both
	a file with textual and with HTML representation. The HTML file shows a 
	summary that gives a good overview of the test run. It also has links 
	to each individual test case log file for quick viewing with an HTML 
	browser.</p>
      
      <p>The minor log files contain full details of every single test
	case, each in a separate file. This way, it is
	straightforward	to compare the latest results to that of previous
	test runs, even if the set of test cases changes. If application SASL
	is running, its logs are also printed to the current minor log file by the
	<seealso marker="common_test:ct_hooks_chapter#builtin_cths">
	  cth_log_redirect built-in hook</seealso>.
      </p>

      <p>The full name of the minor log file (that is, the name of the file
	including the absolute directory path) can be read during execution
	of the test case. It comes as value in tuple
	<c>{tc_logfile,LogFileName}</c> in the <c>Config</c> list (which means it
	can also be read by a pre- or post <c>Common Test Hook</c> function). Also,
	at the start of a test case, this data is sent with an event
	to any installed event handler.	For details, see section
	<seealso marker="event_handler_chapter#event_handling">Event Handling</seealso>.
      </p>

      <p>The log files are written continuously during a test run and links are
	always created initially when a test starts. Thevtest progress can therefore 
	be followed simply by refreshing pages in the HTML browser.
	Statistics totals are not presented until a test is complete however.</p>

	<section>
	  <marker id="logopts"></marker>
	  <title>Log Options</title>
	  <p>With start flag <c>logopts</c> options that modify some aspects 
	  of the logging behavior can be specified.
	  The following options are available:</p>
	  <taglist>
	    <tag><c>no_src</c></tag>
	    <item><p>The HTML version of the test suite source code is not 
	    generated during the test run (and is consequently not available 
	    in the log file system).</p></item>
	    <tag><c>no_nl</c></tag>
	    <item><p><c>Common Test</c> does not add a newline character <c>(\n)</c> 
	    to the end of an output string that it receives from a call to, for example, 
	    <c>io:format/2</c>, and which it prints to the test case log.</p></item>
	    </taglist>

	  <p>For example, if a test is started with:</p>
	  <p><c>$ ct_run -suite my_SUITE -logopts no_src</c></p>
	  <p>then printouts during the test made by successive calls to <c>io:format("x")</c>,
	  appears in the test case log as:</p>
	  <p><c>xxx</c></p>
	  <p>instead of each <c>x</c> printed on a new line, which is the default behavior.</p>
	</section>

	<section>
	  <marker id="table_sorting"></marker>
	  <title>Sorting HTML Table Columns</title>
	  <p>By clicking the name in the column header of any table 
	    (for example, "Ok", "Case", "Time", and so on), the table rows are sorted 
	    in whatever order makes sense for the type of value (for example,
	    numerical for "Ok" or "Time", and alphabetical for "Case"). The sorting is 
	    performed through JavaScript code, automatically inserted into the HTML 
	    log files. <c>Common Test</c> uses the <url href="http://jquery.com">jQuery</url> 
	    library and the
	    <url href="http://tablesorter.com">tablesorter</url> plugin, 
	    with customized sorting functions, for this implementation.</p>
	</section>

	<section>
	  <title>The Unexpected I/O Log</title>
	  <p>The test suites overview page includes a link to the Unexpected I/O Log.
	  In this log, <c>Common Test</c> saves printouts made with
	  <seealso marker="ct#log-2"><c>ct:log/2</c></seealso> and 
	  <seealso marker="ct#pal-2"><c>ct:pal/2</c></seealso>, as well as captured system 
	  error- and progress reports, which cannot be associated with particular test cases and
	  therefore cannot be written to individual test case log files. This occurs,
	  for example, if a log printout is made from an external process (not a test 
	  case process), <em>or</em> if an error- or progress report comes in, during a short 
	  interval while <c>Common Test</c> is not executing a test case or configuration 
	  function, <em>or</em> while <c>Common Test</c> is currently executing a parallel 
	  test case group.</p>
	</section>

	<section>
	  <marker id="pre_post_test_io_log"></marker>
	  <title>The Pre- and Post Test I/O Log</title>
	  <p>The <c>Common Test</c> Framework Log page includes links to the
	  Pre- and Post Test I/O Log. In this log, <c>Common Test</c> saves printouts made 
	  with <c>ct:log/2</c> and <c>ct:pal/2</c>, as well as captured system error-
	  and progress reports, which take place before, and after, the test run.
	  Examples of this are printouts from a CT hook init- or terminate function, or
	  progress reports generated when an OTP application is started from a CT hook
	  init function. Another example is an error report generated because of
	  a failure when an external application is stopped from a CT hook terminate function.
	  All information in these examples ends up in the Pre- and Post Test I/O Log.
	  For more information on how to synchronize test runs with external user
	  applications, see section
	  <seealso marker="ct_hooks_chapter#synchronizing">Synchronizing</seealso>
	  in section Common Test Hooks.</p>
	  <note><p>Logging to file with <c>ct:log/2</c> or <c>ct:pal/2</c>
	  only works when <c>Common Test</c> is running. Printouts with <c>ct:pal/2</c>
	  are however always displayed on screen.</p></note>
	</section>
      </section>
  
      <section>
	<marker id="html_stylesheet"></marker>
	<title>HTML Style Sheets</title>
	<p><c>Common Test</c> uses an HTML Style Sheet (CSS file) to control the look of
	  the HTML log files generated during test runs. If the log files are not 
	  displayed correctly in the browser of your choice, or you prefer a more 
	  primitive ("pre <c>Common Test</c> v1.6") look of the logs, use the start 
	  flag/option:</p>
	  <pre>
 basic_html</pre>
	<p>This disables the use of style sheets and JavaScripts (see
	  <seealso marker="#table_sorting">Sorting HTML Table Columns</seealso>).</p>
	  
	<p><c>Common Test</c> includes an <em>optional</em> feature to allow
	  user HTML style sheets for customizing printouts. The
	  functions in <c>ct</c> that print to a test case HTML log
	  file (<c>log/3</c> and <c>pal/3</c>) accept <c>Category</c>
	  as first argument. With this argument a category can be specified 
	  that can be mapped to a selector in a CSS
	  definition. This is useful, especially for coloring text
	  differently depending on the type of (or reason for) the
	  printout. Say you want one color for test system
	  configuration information, a different one for test system
	  state information, and finally one for errors detected by the
	  test case functions. The corresponding style sheet can
	  look as follows:</p>

	<pre>
 div.sys_config  { background:blue; color:white }
 div.sys_state   { background:yellow; color:black }
 div.error       { background:red; color:white }</pre>

	<p>To install the CSS file (<c>Common Test</c> inlines the definition in the 
	  HTML code), the name can be provided when executing <c>ct_run</c>.</p>
	  <p><em>Example:</em></p>

	<pre>
 $ ct_run -dir $TEST/prog -stylesheet $TEST/styles/test_categories.css</pre>

	  <p>Categories in a CSS file installed with flag <c>-stylesheet</c>
	    are on a global test level in the sense that they can be used in any 
	    suite that is part of the test run.</p>

	  <p>Style sheets can also be installed on a per suite and
	  per test case basis.</p>
	  <p><em>Example:</em></p>

	<pre>
 -module(my_SUITE).
 ...
 suite() -> [..., {stylesheet,"suite_categories.css"}, ...].
 ...
 my_testcase(_) ->
     ...
     ct:log(sys_config, "Test node version: ~p", [VersionInfo]),
     ...
     ct:log(sys_state, "Connections: ~p", [ConnectionInfo]),
     ...
     ct:pal(error, "Error ~p detected! Info: ~p", [SomeFault,ErrorInfo]),
     ct:fail(SomeFault).</pre>

	<p>If the style sheet is installed as in this example, the categories are 
	  private to the suite in question. They can be used by all test cases in the 
	  suite, but cannot be used by other suites. A suite private style sheet, 
	  if specified, is used in favor of a global style sheet (one specified 
	  with flag <c>-stylesheet</c>). A stylesheet tuple (as returned by <c>suite/0</c> 
	  above) can also be returned from a test case information function. In this case the 
	  categories specified in the style sheet can only be used in that particular 
	  test case. A test case private style sheet is used in favor of a suite or 
	  global level style sheet.
	</p>

	<p>In a tuple <c>{stylesheet,CSSFile}</c>, if <c>CSSFile</c> is specified
	  with a path, for example, <c>"$TEST/styles/categories.css"</c>, this full
	  name is used to locate the file. However, if only the file name is specified,
	  for example, <c>categories.css</c>, the CSS file is assumed to be located
	  in the data directory, <c>data_dir</c>, of the suite. The latter use is
	  recommended, as it is portable compared to hard coding path names in the 
	  suite.</p>

	<p>Argument <c>Category</c> in the previous example can have the
	  value (atom) <c>sys_config</c> (white on blue), <c>sys_state</c>
	  (black on yellow), or <c>error</c> (white on red).</p>
  </section>

  <section>
    <marker id="repeating_tests"></marker>
    <title>Repeating Tests</title>    
    <p>You can order <c>Common Test</c> to repeat the tests you specify. You can choose
       to repeat tests a number of times, repeat tests for a specific period of time, 
       or repeat tests until a particular stop time is reached. If repetition is controlled by
       time, an action for <c>Common Test</c> to take upon time-out can be specified. 
       Either <c>Common Test</c> performs all tests in the current run 
       before stopping, or it stops when the current test job is finished. Repetition 
       can be activated by <c>ct_run</c> start flags, or tuples in the <c>ct:run:test/1</c>
       option list argument. The flags (options in parentheses) are the following:</p>
       <list type="bulleted">
       <item><c>-repeat N ({repeat,N})</c>, where <c>N</c> is a positive integer</item>
       <item><c>-duration DurTime ({duration,DurTime})</c>, where <c>DurTime</c> is the duration</item>
       <item><c>-until StopTime ({until,StopTime})</c>, where <c>StopTime</c> is finish time</item>
       <item><c>-force_stop ({force_stop,true})</c></item>
       <item><c>-force_stop skip_rest ({force_stop,skip_rest})</c></item>
       </list>
	  <taglist>
	    <tag><c>DurTime</c></tag>
	    <item><p>The duration time is specified as <c>HHMMSS</c>, for example, <c>-duration 012030</c> 
	    or <c>{duration,"012030"}</c></p>, which means that the tests are executed and 
	    (if time allows) repeated until time-out occurs after 1 hour, 20 minutes, and 30 seconds.
	    </item>
	    <tag><c>StopTime</c></tag>
	    <item><p>The finish time can be specified as <c>HHMMSS</c> and is then interpreted as a 
	    time today (or possibly tomorrow), but can also be specified as <c>YYMoMoDDHHMMSS</c>,
	    for example, <c>-until 071001120000</c> or <c>{until,"071001120000"}</c>. This means
	    that the tests are executed and (if time allows) repeated, until 12 o'clock on the 1st 
	    of October 2007.</p>
	    </item>
	  </taglist>

       <p>When time-out occurs, <c>Common Test</c> never aborts the ongoing test case,
          as this can leave the SUT in an undefined, and possibly bad, state.
	  Instead <c>Common Test</c>, by default, finishes the current test
	  run before stopping. If flag <c>force_stop</c> is
	  specified, <c>Common Test</c> stops when the current test job
	  is finished. If flag <c>force_stop</c> is specified with
	  <c>skip_rest</c>, <c>Common Test</c> only completes the current
	  test case and skips the remaining tests in the test job.</p>
	  <note><p>As <c>Common Test</c> always finishes at least the current test case,
	  the time specified with <c>duration</c> or <c>until</c> is never definitive.</p></note>

       <p>Log files from every repeated test run is saved in normal <c>Common Test</c> 
       fashion (described earlier).</p>
       <p><c>Common Test</c> might later support an optional feature to only store the last (and possibly 
       the first) set of logs of repeated test runs, but for now the user must be careful not 
       to run out of disk space if tests are repeated during long periods of time.</p>

       <p>For each test run that is part of a repeated session, information about the
          particular test run is printed in the <c>Common Test</c> Framework Log. The information
	  includes the repetition number, remaining time, and so on.</p>

       <p><em>Example 1:</em></p>
       <pre>
 $ ct_run -dir $TEST_ROOT/to1 $TEST_ROOT/to2 -duration 001000 -force_stop</pre>

       <p>Here, the suites in test directory <c>to1</c>, followed by the suites in <c>to2</c>, are 
          executed in one test run. A time-out event occurs after 10 minutes. As long as there is 
	  time left, <c>Common Test</c> repeats the test run (that is, starting over with test <c>to1</c>). 
	  After time-out, <c>Common Test</c> stops when the current job is finished
	  (because of flag <c>force_stop</c>). As a result, the specified test run can be 
	  aborted after test <c>to1</c> and before test <c>to2</c>.</p>

       <p><em>Example 2:</em></p>
       <pre>
 $ ct_run -dir $TEST_ROOT/to1 $TEST_ROOT/to2 -duration 001000 -forces_stop skip_rest</pre>

       <p>Here, the same tests as in Example 1 are run, but with flag <c>force_stop</c> set to 
       <c>skip_rest</c>. If time-out occurs while executing tests in directory <c>to1</c>, 
          the remaining test cases in <c>to1</c> are skipped and the test is aborted without 
	  running the tests in <c>to2</c> another time. If time-out occurs while executing 
	  tests in directory <c>to2</c>, the remaining test cases in <c>to2</c> are skipped and 
	  the test is aborted.</p>

       <p><em>Example 3:</em></p>
       <pre>
 $ date
 Fri Sep 28 15:00:00 MEST 2007

 $ ct_run -dir $TEST_ROOT/to1 $TEST_ROOT/to2 -until 160000</pre>

       <p>Here, the same test run as in the previous examples are executed (and possibly repeated). 
          However, when the time-out occurs, after 1 hour, <c>Common Test</c> finishes the entire 
	  test run before stopping (that is, both <c>to1</c> and <c>to2</c> are always executed in 
          the same test run).</p>
       
       <p><em>Example 4:</em></p>
       <pre>
 $ ct_run -dir $TEST_ROOT/to1 $TEST_ROOT/to2 -repeat 5</pre>

       <p>Here, the test run, including both the <c>to1</c> and the <c>to2</c> test, is repeated 
          five times.</p>

       <note><p>Do not confuse this feature with the <c>repeat</c> property of a test
          case group. The options described here are used to repeat execution of entire test runs,
	  while the <c>repeat</c> property of a test case group makes it possible to repeat
	  execution of sets of test cases within a suite. For more information about the latter,
	  see section <seealso marker="write_test_chapter#test_case_groups">Test Case Groups </seealso>
	  in section Writing Test Suites.</p></note>
  </section>

  <section>
    <marker id="silent_connections"></marker>
      <title>Silent Connections</title>
      <p>The protocol handling processes in <c>Common Test</c>, implemented by <c>ct_telnet</c>,
      <c>ct_ssh</c>, <c>ct_ftp</c>, and so on, do verbose printing to the test case logs. 
      This can be switched off with flag <c>-silent_connections</c>:</p>
      
      <pre>
 ct_run -silent_connections [conn_types]</pre>
      
      <p>Here, <c>conn_types</c> specifies SSH, Telnet, FTP, RPC, and/or SNMP.</p>
      
      <p><em>Example 1:</em></p>
      
      <pre>
 ct_run ... -silent_connections ssh telnet</pre>
      <p>This switches off logging for SSH and Telnet connections.</p>
      
      <p><em>Example 2:</em></p>
      
      <pre>
 ct_run ... -silent_connections</pre>
      <p>This switches off logging for all connection types.</p>
      
      
      <p>Fatal communication error and reconnection attempts are always printed, even if 
         logging has been suppressed for the connection type in question. However, operations
         such as sending and receiving data are performed silently.</p>
      
      <p><c>silent_connections</c> can also be specified in a test suite. This is
	accomplished by returning a tuple, <c>{silent_connections,ConnTypes}</c>, in the
	<c>suite/0</c> or test case information list. If <c>ConnTypes</c> is a list of atoms 
	(SSH, Telnet, FTP, RPC and/or SNMP), output for any corresponding connections 
	are suppressed. Full logging is by default enabled for any connection of type not 
	specified in <c>ConnTypes</c>. Hence, if <c>ConnTypes</c> is the empty list, logging 
	is enabled for all connections.</p>
      
	<p><em>Example 3:</em></p>
      
      <pre>
 -module(my_SUITE).

 suite() -> [..., {silent_connections,[telnet,ssh]}, ...].

 ...

 my_testcase1() ->
     [{silent_connections,[ssh]}].

 my_testcase1(_) ->
     ...

 my_testcase2(_) ->
     ...</pre>
      
      <p>In this example, <c>suite/0</c> tells <c>Common Test</c> to suppress
	printouts from Telnet and SSH connections. This is valid for
	all test cases. However, <c>my_testcase1/0</c> specifies that
	for this test case, only SSH is to be silent. The result is
	that <c>my_testcase1</c> gets Telnet information (if any) printed
	in the log, but not SSH information. <c>my_testcase2</c> gets no
	information from either connection printed.</p>
      
	<p><c>silent_connections</c> can also be specified with a term
	in a test specification
	(see section <seealso marker="run_test_chapter#test_specifications">Test
	Specifications</seealso> in section Running Tests and Analyzing Results).
	Connections provided with start	flag/option <c>silent_connections</c>
	are merged with any connections listed in the test specification.</p>

	<p>Start flag/option <c>silent_connections</c> and the test
	specification term override any settings made by the information functions
	inside the test suite.</p>
      
      <note><p>In the current <c>Common Test</c> version, the
	<c>silent_connections</c> feature only works for Telnet
	and SSH connections. Support for other connection types can be added
	in future <c>Common Test</c> versions.</p></note>
      
  </section>
</chapter>