<?xml version="1.0" encoding="latin1" ?>
<!DOCTYPE chapter SYSTEM "chapter.dtd">
<chapter>
<header>
<copyright>
<year>2004</year><year>2009</year>
<holder>Ericsson AB. All Rights Reserved.</holder>
</copyright>
<legalnotice>
The contents of this file are subject to the Erlang Public License,
Version 1.1, (the "License"); you may not use this file except in
compliance with the License. You should have received a copy of the
Erlang Public License along with this software. If not, it can be
retrieved online at http://www.erlang.org/.
Software distributed under the License is distributed on an "AS IS"
basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
the License for the specific language governing rights and limitations
under the License.
</legalnotice>
<title>Config Files</title>
<prepared>Siri Hansen, Peter Andersson</prepared>
<docno></docno>
<date></date>
<rev></rev>
<file>config_file_chapter.xml</file>
</header>
<section>
<title>General</title>
<p>The Common Test framework uses configuration files to
describe data related to a test and/or an SUT (System Under Test).
The configuration data makes it possible to change properties without
changing the test program itself. Configuration data can for example be:</p>
<list>
<item>Addresses to the test plant or other instruments</item>
<item>Filenames for files needed by the test</item>
<item>Program names for programs that shall be run by the test</item>
<item>Any other variable that is needed by the test</item>
</list>
</section>
<section>
<title>Syntax</title>
<p>A configuration file can contain any number of elements of the type:</p>
<pre>
{Key,Value}.</pre>
<p>where</p>
<pre>
Key = atom()
Value = term() | [{Key,Value}]</pre>
</section>
<section>
<title>Requiring and reading configuration data</title>
<marker id="require_config_data"></marker>
<p>In a test suite, one must <em>require</em> that a configuration
variable exists before attempting to read the associated
value in a test case.</p>
<p><c>require</c> is an assert statement that can be part of the <seealso
marker="write_test_chapter#suite">test suite info function</seealso> or
<seealso marker="write_test_chapter#info_function">test case info
function</seealso>. If the required variable is not available, the
test is skipped (unless a default value has been specified, see the
<seealso marker="write_test_chapter#info_function">test case info
function</seealso> chapter for details). There is also a function
<c>ct:require/[1,2]</c> which can be called from a test case
in order to check if a specific variable is available. The return
value from this function must be checked explicitly and appropriate
action be taken depending on the result (e.g. to skip the test case
if the variable in question doesn't exist).</p>
<p>A <c>require</c> statement in the test suite info- or test case
info-list should look like this:
<c>{require,Required}</c> or <c>{require,Name,Required}</c>. The
arguments <c>Name</c> and <c>Required</c> are the same as the
arguments to <c>ct:require/[1,2]</c> which are described in the
reference manual for <seealso marker="ct">ct</seealso>.
<c>Name</c> becomes an alias for the configuration variable
<c>Required</c>, and can be used as reference to the configuration
data value. The configuration variable may be associated with an
arbitrary number of alias names, but each name must be unique within
the same test suite. There are two main uses for alias names:</p>
<list>
<item>They may be introduced to identify connections (see below).</item>
<item>They may used to help adapt configuration data to a test suite
(or test case) and improve readability.</item>
</list>
<p>To read the value of a config variable, use the function
<c>get_config/[1,2,3]</c> which is also described in the reference
manual for <seealso marker="ct">ct</seealso>.</p>
<p>Example:</p>
<pre>
suite() ->
[{require, domain, 'CONN_SPEC_DNS_SUFFIX'}].
...
testcase(Config) ->
Domain = ct:get_config(domain),
...</pre>
</section>
<section>
<title>Using configuration variables defined in multiple files</title>
<p>If a configuration variable is defined in multiple files and you
want to access all possible values, you may use the <c>ct:get_config/3</c>
function and specify <c>all</c> in the options list. The values will then
be returned in a list and the order of the elements corresponds to the order
that the config files were specified at startup. Please see
the <seealso marker="ct">ct</seealso> reference manual for details.</p>
</section>
<section>
<title>Encrypted configuration files</title>
<marker id="encrypted_config_files"></marker>
<p>It is possible to encrypt configuration files containing sensitive data
if these files must be stored in open and shared directories.</p>
<p>Call <c>ct:encrypt_config_file/[2,3]</c> to have Common Test encrypt a
specified file using the DES3 function in the OTP <c>crypto</c> application.
The encrypted file can then be used as a regular configuration file,
in combination with other encrypted files or normal text files. The key
for decrypting the configuration file must be provided when running the test,
however. This can be done by means of the <c>decrypt_key</c> or
<c>decrypt_file</c> flag/option, or a key file in a predefined location.</p>
<p>Common Test also provides decryption functions,
<c>ct:decrypt_config_file/[2,3]</c>, for recreating the original text
files.</p>
<p>Please see the <seealso marker="ct">ct</seealso> reference manual for
more information.</p>
</section>
<section>
<title>Opening connections by using configuration data</title>
<p>There are two different methods for opening a connection
by means of the support functions in e.g. <c>ct_ssh</c>, <c>ct_ftp</c>,
and <c>ct_telnet</c>:</p>
<list>
<item>Using a configuration target name (an alias) as reference.</item>
<item>Using the configuration variable as reference.</item>
</list>
<p>When a target name is used for referencing the configuration data
(that specifies the connection to be opened), the same name may be used
as connection identity in all subsequent calls related to the connection
(also for closing it). It's only possible to have one open connection
per target name. If attempting to open a new connection using a name
already associated with an open connection, Common Test will
return the already existing handle so that the previously opened connection
will be used. This is a practical feature since it makes it possible to
call the function for opening a particular connection whenever
useful. An action like this will not necessarily open any new
connections unless it's required (which could be the case if e.g. the
previous connection has been closed unexpectedly by the server).
Another benefit of using named connections is that it's not
necessary to pass handle references around in the suite for these
connections.
</p>
<p>When a configuration variable name is used as reference to the data
specifying the connection, the handle returned as a result of opening
the connection must be used in all subsequent calls (also for closing
the connection). Repeated calls to the open function with the same
variable name as reference will result in multiple connections
being opened. This can be useful e.g. if a test case needs to open
multiple connections to the same server on the target node (using the
same configuration data for each connection).
</p>
</section>
<section>
<title>Examples</title>
<p>A config file for using the FTP client to access files on a remote
host could look like this:</p>
<pre>
{ftp_host, [{ftp,"targethost"},
{username,"tester"},
{password,"letmein"}]}.
{lm_directory, "/test/loadmodules"}.</pre>
<p>Example of how to assert that the configuration data is available and
use it for an FTP session:</p>
<pre>
init_per_testcase(ftptest, Config) ->
{ok,_} = ct_ftp:open(ftp),
Config.
end_per_testcase(ftptest, _Config) ->
ct_ftp:close(ftp).
ftptest() ->
[{require,ftp,ftp_host},
{require,lm_directory}].
ftptest(Config) ->
Remote = filename:join(ct:get_config(lm_directory), "loadmodX"),
Local = filename:join(?config(priv_dir,Config), "loadmodule"),
ok = ct_ftp:recv(ftp, Remote, Local),
...</pre>
<p>An example of how the above functions could be rewritten
if necessary to open multiple connections to the FTP server:</p>
<pre>
init_per_testcase(ftptest, Config) ->
{ok,Handle1} = ct_ftp:open(ftp_host),
{ok,Handle2} = ct_ftp:open(ftp_host),
[{ftp_handles,[Handle1,Handle2]} | Config].
end_per_testcase(ftptest, Config) ->
lists:foreach(fun(Handle) -> ct_ftp:close(Handle) end,
?config(ftp_handles,Config)).
ftptest() ->
[{require,ftp_host},
{require,lm_directory}].
ftptest(Config) ->
Remote = filename:join(ct:get_config(lm_directory), "loadmodX"),
Local = filename:join(?config(priv_dir,Config), "loadmodule"),
[Handle | MoreHandles] = ?config(ftp_handles,Config),
ok = ct_ftp:recv(Handle, Remote, Local),
...</pre>
</section>
</chapter>
