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

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<chapter>
  <header>
    <copyright>
      <year>2007</year><year>2013</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>Getting Started</title>
    <prepared>Peter Andersson</prepared>
    <docno></docno>
    <date>2011-12-12</date>
    <rev></rev>
    <file>getting_started_chapter.xml</file>
  </header>

  <section>
    <title>Introduction for Newcomers</title>
    <p>
      The purpose of this section is to let the newcomer get started in
      quickly writing and executing some first simple tests with a 
      "learning by example" approach. Most explanations are left for later sections. 
      If you are not much into "learning by example" and prefer more technical
      details, go ahead and skip to the next section.
    </p>
    <p>
      This section demonstrates how simple it is to write a basic 
      (yet for many module testing purposes, often sufficiently complex) 
      test suite and execute its test cases. This is not necessarily
      obvious when you read the remaining sections in this User's Guide.
    </p>
    <note>
      <p>
      To understand what is discussed and examplified here, we recommended 
      you to first read section
      <seealso marker="basics_chapter#basics">Common Test Basics</seealso>.
      </p>
    </note>
    </section>

    <section>
    <title>Test Case Execution</title>
    <p>Execution of test cases is handled as follows:</p>
    
    <image file="tc_execution.gif">
      <icaption>
	Successful and Unsuccessful Test Case Execution
      </icaption>
    </image>

    <p>For each test case that <c>Common Test</c> is ordered to execute, it spawns a
      dedicated process on which the test case function starts
      running. (In parallel to the test case process, an idle waiting timer
      process is started, which is linked to the test case process. If the timer
      process runs out of waiting time, it sends an exit signal to terminate
      the test case process. This is called a <em>timetrap</em>).
    </p>
    <p>In scenario 1, the test case process terminates normally after 
    <c>case A</c> has finished executing its test code without detecting 
    any errors. The test case function returns a value and <c>Common Test</c> 
    logs the test case as successful.
    </p>
    <p>In scenario 2, an error is detected during test <c>case B</c> execution.
      This causes the test <c>case B</c> function to generate an exception
      and, as a result, the test case process exits with reason other than normal. 
      <c>Common Test</c> logs this as an unsuccessful (Failed) test case.
    </p>
    <p>As you can understand from the illustration, <c>Common Test</c> requires
      a test case to generate a runtime error to indicate failure (for example,
      by causing a bad match error or by calling <c>exit/1</c>, preferably
      through the help function 
      <seealso marker="ct#fail-1"><c>ct:fail/1,2</c></seealso>). A successful 
      execution is indicated by a normal return from the test case function.
    </p>
    </section>

    <section>
    <title>A Simple Test Suite</title>
    <p>As shown in section 
    <seealso marker="basics_chapter#External_Interfaces">Common Test Basics</seealso>,
    the test suite module implements
      <seealso marker="common_test">callback functions</seealso>
      (mandatory or optional) for various purposes, for example:
    </p>
      <list type="bulleted">
	<item>Init/end configuration function for the test suite</item>
	<item>Init/end configuration function for a test case</item>
	<item>Init/end configuration function for a test case group</item>
	<item>Test cases</item>
      </list>
    <p> 
     The configuration functions are optional. The following example is a test suite 
     without configuration functions, including one simple test case, to 
     check that module <c>mymod</c> exists (that is, can be successfully loaded by the 
     code server):
    </p>
    <pre>
 -module(my1st_SUITE).
 -compile(export_all).

 all() ->
     [mod_exists].

 mod_exists(_) ->
     {module,mymod} = code:load_file(mymod).</pre>
    <p>
      If the operation fails, a bad match error occurs that terminates the test case.
    </p>
    </section>

    <section>
    <title>A Test Suite with Configuration Functions</title>
    <p>
      If you need to perform configuration operations to run your test, you can
      implement configuration functions in your suite. The result from a
      configuration function is configuration data, or <c>Config</c>.
      This is a list of key-value tuples that get passed from the configuration
      function to the test cases (possibly through configuration functions on
      "lower level"). The data flow looks as follows:
    </p>

    <image file="config.gif">
      <icaption>
	Configuration Data Flow in a Suite
      </icaption>
    </image>

    <p>
      The following example shows a test suite that uses configuration functions
      to open and close a log file for the test cases (an operation that is
      unnecessary and irrelevant to perform by each test case):
    </p>
    <pre>
 -module(check_log_SUITE).
 -export([all/0, init_per_suite/1, end_per_suite/1]).
 -export([check_restart_result/1, check_no_errors/1]).

 -define(value(Key,Config), proplists:get_value(Key,Config)).

 all() -> [check_restart_result, check_no_errors].

 init_per_suite(InitConfigData) ->
     [{logref,open_log()} | InitConfigData].

 end_per_suite(ConfigData) ->
     close_log(?value(logref, ConfigData)).

 check_restart_result(ConfigData) ->
     TestData = read_log(restart, ?value(logref, ConfigData)),
     {match,_Line} = search_for("restart successful", TestData).

 check_no_errors(ConfigData) ->
     TestData = read_log(all, ?value(logref, ConfigData)),
     case search_for("error", TestData) of
	 {match,Line} -> ct:fail({error_found_in_log,Line});
	 nomatch -> ok
     end.</pre>
    <p>
      The test cases verify, by parsing a log file, that our SUT has performed 
      a successful restart and that no unexpected errors are printed.
    </p>

    <p>To execute the test cases in the recent test suite, type the 
    following on the UNIX/Linux command line (assuming that the suite module
      is in the current working directory):
    </p>
    <pre>
 $ ct_run -dir .</pre>
    <p>or:</p>
    <pre>
 $ ct_run -suite check_log_SUITE</pre>

    <p>To use the Erlang shell to run our test, you can evaluate the following call:
    </p>
    <pre>
 1> ct:run_test([{dir, "."}]).</pre>
    <p>or:</p>
    <pre>
 1> ct:run_test([{suite, "check_log_SUITE"}]).</pre>
    <p>
      The result from running the test is printed in log files in HTML format
      (stored in unique log directories on a different level). The following 
      illustration shows the log file structure:
    </p>

    <image file="html_logs.gif">
      <icaption>
	HTML Log File Structure
      </icaption>
    </image>
  </section>

  <section>
    <title>Questions and Answers</title>

    <p>Here follows some questions that you might have after reading this section 
    with corresponding tips and links to the answers:
    </p>
      
      <list type="bulleted">
	<item><p><em>Question:</em> 
	"How and where can I specify variable data for my tests that must not 
	be hard-coded in the test suites (such as hostnames, addresses, and
	  user login data)?"</p>
	  <p><em>Answer:</em> 
	  See section <seealso marker="config_file_chapter#top">External Configuration Data</seealso>.</p>
	</item>

	<item><p><em>Question:</em> "Is there a way to declare different tests and run them
	  in one session without having to write my own scripts? Also, can such
	  declarations be used for regression testing?"</p>
	  <p><em>Answer:</em> See section
	  <seealso marker="run_test_chapter#test_specifications">Test Specifications</seealso>
	  in section Running Tests and Analyzing Results.
	  </p>
	</item>

	<item><p><em>Question:</em> "Can test cases and/or test runs be automatically repeated?"</p>
	<p><em>Answer:</em> Learn more about
	  <seealso marker="write_test_chapter#test_case_groups">Test Case Groups</seealso>
	  and read about start flags/options in section
	  <seealso marker="run_test_chapter#ct_run">Running Tests</seealso> and in
	  the Reference Manual.</p>
	</item>

	<item><p><em>Question:</em> "Does <c>Common Test</c> execute my test cases in sequence or in parallel?"</p>
	<p><em>Answer:</em> See
	  <seealso marker="write_test_chapter#test_case_groups">Test Case Groups</seealso>
	in section Writing Test Suites.</p>
	</item>

	<item><p><em>Question:</em> "What is the syntax for timetraps (mentioned earlier), and how do I set them?"</p>
	  <p><em>Answer:</em> This is explained in the
	  <seealso marker="write_test_chapter#timetraps">Timetrap Time-Outs</seealso>
	  part of section Writing Test Suites.</p>
	</item>

	<item><p><em>Question:</em> "What functions are available for logging and printing?"</p>
	<p><em>Answer:</em> See
	  <seealso marker="write_test_chapter#logging">Logging</seealso>
	in section Writing Test Suites.</p>
	</item>

	<item><p><em>Question:</em> "I need data files for my tests. Where do I store them preferably?"</p>
	  <p><em>Answer:</em> See
	  <seealso marker="write_test_chapter#data_priv_dir">Data and Private
	  Directories</seealso>.</p>
	</item>

	<item><p><em>Question:</em> "Can I start with a test suite example, please?"</p>
	  <p><em>Answer:</em> <seealso marker="example_chapter#top">Welcome!</seealso></p>
	</item>
      </list>
      <p>You probably want to get started on your own first test suites now, while
      at the same time digging deeper into the <c>Common Test</c> User's Guide and Reference Manual.
      There are much more to learn about the things that have been introduced
      in this section. There are also many other useful features to learn, 
      so please continue to the other sections and have fun.
      </p>
    </section>
</chapter>