6 Running Test Suites

6.1 Using the Common Test Framework

The Common Test Framework provides a high level operator interface for testing. It adds the following features to the Erlang/OTP Test Server:

Automatic compilation of test suites (and help modules).
Creation of additional HTML pages for better overview.
Single command interface for running all available tests.
Handling of configuration files specifying data related to the System Under Test (and any other variable data).
Mode for running multiple independent test sessions in parallel with central control and configuration.

6.2 Automatic compilation of test suites and help modules

When Common Test starts, it will automatically attempt to compile any suites included in the specified tests. If particular suites have been specified, only those suites will be compiled. If a particular test object directory has been specified (meaning all suites in this directory should be part of the test), Common Test runs make:all/1 in the directory to compile the suites.

If compilation should fail for one or more suites, the compilation errors are printed to tty and the operator is asked if the test run should proceed without the missing suites, or be aborted. If the operator chooses to proceed, it is noted in the HTML log which tests have missing suites.

Any help module (i.e. 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, will also be automatically compiled. A help module will not be mistaken for a test suite (unless it has a "_SUITE" name of course). 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.

If test suites or help modules include header files stored in other locations than the test directory, you may specify these include directories by means of the -include flag with run_test, or the include option with ct:run_test/1. In addition to this, an include path may be specified with an OS environment variable; CT_INCLUDE_PATH. Example (bash):

$ export CT_INCLUDE_PATH=~testuser/common_suite_files/include:~testuser/common_lib_files/include

Common Test will pass all include directories (specified either with the include flag/option, or the CT_INCLUDE_PATH variable, or both) to the compiler.

It is also possible to specify include directories in test specifications (see below).

If the user wants to run all test suites for a test object (or OTP application) by specifying only the top directory (e.g. with the dir start flag/option), Common Test will primarily look for test suite modules in a subdirectory named test. If this subdirectory doesn't exist, the specified top directory is assumed to be the actual test directory, and test suites will be read from there instead.

It is possible to disable the automatic compilation feature by using the -no_auto_compile flag with run_test, or the {auto_compile,false} option with ct:run_test/1. With automatic compilation disabled, the user is responsible for compiling the test suite modules (and any help modules) before the test run. Common Test will only verify that the specified test suites exist before starting the tests.

6.3 Running tests from the UNIX command line

The script run_test can be used for running tests from the Unix/Linux command line, e.g.

run_test -config <configfilenames> -dir <dirs>
run_test -config <configfilenames> -suite <suiteswithfullpath>
run_test -config <configfilenames> -suite <suitewithfullpath> -group <groupnames> -case <casenames>

Examples:

$ run_test -config $CFGS/sys1.cfg $CFGS/sys2.cfg -dir $SYS1_TEST $SYS2_TEST

$ run_test -suite $SYS1_TEST/setup_SUITE $SYS2_TEST/config_SUITE

$ run_test -suite $SYS1_TEST/setup_SUITE -case start stop

$ run_test -suite $SYS1_TEST/setup_SUITE -group installation -case start stop

Other flags that may be used with run_test:

-logdir <dir>, specifies where the HTML log files are to be written.
-refresh_logs, refreshes the top level HTML index files.
-vts, start web based GUI (see below).
-shell, start interactive shell mode (see below).
-step [step_opts], step through test cases using the Erlang Debugger (see below).
-spec <testspecs>, use test specification as input (see below).
-allow_user_terms, allows user specific terms in a test specification (see below).
-silent_connections [conn_types], tells Common Test to suppress printouts for specified connections (see below).
-stylesheet <css_file>, points out a user HTML style sheet (see below).
-cover <cover_cfg_file>, to perform code coverage test (see Code Coverage Analysis).
-event_handler <event_handlers>, to install event handlers.
-include, specifies include directories (see above).
-no_auto_compile, disables the automatic test suite compilation feature (see above).
-repeat <n>, tells Common Test to repeat the tests n times (see below).
-duration <time>, tells Common Test to repeat the tests for duration of time (see below).
-until <stop_time>, tells Common Test to repeat the tests until stop_time (see below).
-force_stop, on timeout, the test run will be aborted when current test job is finished (see below).
-decrypt_key <key>, provides a decryption key for encrypted configuration files.
-decrypt_file <key_file>, points out a file containing a decryption key for encrypted configuration files.
-basic_html, switches off html enhancements that might not be compatible with older browsers.

Note

Directories passed to Common Test may have either relative or absolute paths.

Note

Arbitrary start flags to the Erlang Runtime System may also be passed as parameters to run_test. It is, for example, useful to be able to pass directories that should be added to the Erlang code server search path with the -pa or -pz flag. If you have common help- or library modules for test suites (separately compiled), stored in other directories than the test suite directories, these help/lib directories are preferrably added to the code path this way. Example:

$ run_test -dir ./chat_server -logdir ./chat_server/testlogs -pa $PWD/chat_server/ebin

Note how in this example, the absolute path of the chat_server/ebin directory is passed to the code server. This is essential since relative paths are stored by the code server as relative, and Common Test changes the current working directory of the Erlang Runtime System during the test run!

For details on how to generate the run_test script, see the Installation chapter.

6.4 Running tests from the Web based GUI

The web based GUI, VTS, is started with the run_test script. From the GUI you can load config files, and select directories, suites and cases to run. You can also state the config files, directories, suites and cases on the command line when starting the web based GUI.

run_test -vts
run_test -vts -config <configfilename>
run_test -vts -config <configfilename> -suite <suitewithfullpath> -case <casename>

From the GUI you can run tests and view the result and the logs.

Note that run_test -vts will try to open the Common Test start page in an existing web browser window or start the browser if it is not running. Which browser should be started may be specified with the browser start command option:

run_test -vts -browser <browser_start_cmd>

Example:

$ run_test -vts -browser 'firefox&'

Note that the browser must run as a separate OS process or VTS will hang!

If no specific browser start command is specified, netscape will be the default browser on Unix platforms and Internet Explorer on Windows. If Common Test fails to start a browser automatically, start your favourite browser manually instead and type in the URL that Common Test displays in the shell.

6.5 Running tests from the Erlang shell or from an Erlang program

Common Test provides an Erlang API for running tests. The main (and most flexible) function for specifying and executing tests is called ct:run_test/1. This function takes the same start parameters as the run_test script described above, only the flags are instead given as options in a list of key-value tuples. E.g. a test specified with run_test like:

$ run_test -suite ./my_SUITE -logdir ./results

is with ct:run_test/1 specified as:

1> ct:run_test([{suite,"./my_SUITE"},{logdir,"./results"}]).

For detailed documentation, please see the ct manual page.

6.6 Running the interactive shell mode

You can start Common Test in an interactive shell mode where no automatic testing is performed. Instead, in this mode, Common Test 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.

The shell mode is useful e.g. for debugging test suites, for analysing and debugging the SUT during "simulated" test case execution, and for trying out various operations during test suite development.

To invoke the interactive shell mode, you can start an Erlang shell manually and call ct:install/1 to install any configuration data you might need (use [] as argument otherwise), then call ct:start_interactive/0 to start Common Test. If you use the run_test script, you may start the Erlang shell and Common Test in the same go by using the -shell and, optionally, the -config flag:

run_test -shell
run_test -shell -config <configfilename>

If no config file is given with the run_test command, a warning will be displayed. If Common Test has been run from the same directory earlier, the same config file(s) will be used again. If Common Test has not been run from this directory before, no config files will be available.

If any functions using "required config data" (e.g. ct_telnet or ct_ftp functions) are to be called from the erlang shell, config data must first be required with ct:require/[1,2]. This is equivalent to a require statement in the Test Suite Info Function or in the Test Case Info Function.

Example:

 
       1> ct:require(unix_telnet, unix).
       ok
       2> ct_telnet:open(unix_telnet).
       {ok,<0.105.0>}
       4> ct_telnet:cmd(unix_telnet, "ls .").
       {ok,["ls .","file1  ...",...]}

Everything that Common Test normally prints in the test case logs, will in the interactive mode be written to a log named ctlog.html in the ct_run.<timestamp> directory. A link to this file will be available in the file named last_interactive.html in the directory from which you executed run_test. Currently, specifying a different root directory for the logs than the current working directory, is not supported.

If you wish to exit the interactive mode (e.g. to start an automated test run with ct:run_test/1), call the function ct:stop_interactive/0. This shuts down the running ct application. Associations between configuration names and data created with require are consequently deleted. ct:start_interactive/0 will get you back into interactive mode, but the previous state is not restored.

6.7 Step by step execution of test cases with the Erlang Debugger

By means of run_test -step [opts], or by passing the {step,Opts} option to ct:run_test/1, it is possible to get the Erlang Debugger started automatically and use its graphical interface to investigate the state of the current test case and to execute it step by step and/or set execution breakpoints.

If no extra options are given with the step flag/option, breakpoints will be set automatically on the test cases that are to be executed by Common Test, and those functions only. If the step option config is specified, breakpoints will also be initially set on the configuration functions in the suite, i.e. init_per_suite/1, end_per_suite/1, init_per_testcase/2 and end_per_testcase/2.

Common Test enables the Debugger auto attach feature, which means that for every new interpreted test case function that starts to execute, a new trace window will automatically pop up. (This is because each test case executes on a dedicated Erlang process). Whenever a new test case starts, Common Test will attempt to close the inactive trace window of the previous test case. However, if you prefer that Common Test leaves inactive trace windows, use the keep_inactive option.

The step functionality can be used together with the suite and the suite + case/testcase flag/option, but not together with dir.

6.8 Using test specifications

The most expressive way to specify what to test is to use a so called test specification. A test specification is a sequence of Erlang terms. The terms may be declared in a text file or passed to the test server at runtime as a list (see run_testspec/1 in the manual page for ct). There are two general types of terms: configuration terms and test specification terms.

With configuration terms it is possible to import configuration data (similar to run_test -config), specify HTML log directories (similar to run_test -logdir), give aliases to test nodes and test directories (to make a specification easier to read and maintain), enable code coverage analysis (see the Code Coverage Analysis chapter) and specify event_handler plugins (see the Event Handling chapter). There is also a term for specifying include directories that should be passed on to the compiler when automatic compilation is performed (similar to run_test -include, see above).

With test specification terms it is possible to state exactly which tests should run and in which order. A test term specifies either one or more suites or one or more test cases. An arbitrary number of test terms may be declared in sequence. A test term can also specify one or more test suites or test cases to be skipped. Skipped suites and cases are not executed and show up in the HTML test log as SKIPPED.

Note

It is not yet possible to specify test case groups in test specifications. This will be supported in a soon upcoming release.

Below is the test specification syntax. Test specifications can be used to run tests both in a single test host environment and in a distributed Common Test environment. Node parameters are only relevant in the latter (see the chapter about running Common Test in distributed mode for information). For details on the event_handler term, see the Event Handling chapter.

Config terms:

      {node, NodeAlias, Node}.
 
      {cover, CoverSpecFile}.
      {cover, NodeRef, CoverSpecFile}.
      
      {include, IncludeDirs}.
      {include, NodeRefs, IncludeDirs}.

      {config, ConfigFiles}.
      {config, NodeRefs, ConfigFiles}.
      
      {alias, DirAlias, Dir}.
      
      {logdir, LogDir}.                                        
      {logdir, NodeRefs, LogDir}.
      
      {event_handler, EventHandlers}.
      {event_handler, NodeRefs, EventHandlers}.
      {event_handler, EventHandlers, InitArgs}.
      {event_handler, NodeRefs, EventHandlers, InitArgs}.

Test terms:

      {suites, DirRef, Suites}.                                
      {suites, NodeRefs, DirRef, Suites}.
      
      {cases, DirRef, Suite, Cases}.                           
      {cases, NodeRefs, DirRef, Suite, Cases}.

      {skip_suites, DirRef, Suites, Comment}.
      {skip_suites, NodeRefs, DirRef, Suites, Comment}.
      
      {skip_cases, DirRef, Suite, Cases, Comment}.
      {skip_cases, NodeRefs, DirRef, Suite, Cases, Comment}.

Types:

      NodeAlias     = atom()
      Node          = node()
      NodeRef       = NodeAlias | Node | master
      NodeRefs      = all_nodes | [NodeRef] | NodeRef
      CoverSpecFile = string()
      IncludeDirs   = string() | [string()]
      ConfigFiles   = string() | [string()]
      DirAlias      = atom()
      Dir           = string()
      LogDir        = string()
      EventHandlers = atom() | [atom()]
      InitArgs      = [term()]
      DirRef        = DirAlias | Dir
      Suites        = atom() | [atom()] | all
      Cases         = atom() | [atom()] | all
      Comment       = string() | ""

Example:

      {logdir, "/home/test/logs"}.
      
      {config, "/home/test/t1/cfg/config.cfg"}.
      {config, "/home/test/t2/cfg/config.cfg"}.
      {config, "/home/test/t3/cfg/config.cfg"}.
      
      {alias, t1, "/home/test/t1"}.
      {alias, t2, "/home/test/t2"}.
      {alias, t3, "/home/test/t3"}.
      
      {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"}.

The example specifies the following:

The specified logdir directory will be used for storing the HTML log files (in subdirectories tagged with node name, date and time).
The variables in the specified test system config files will be imported for the test.
Aliases are given for three test system directories. The suites in this example are stored in "/home/test/tX/test".
The first test to run includes all suites for system t1. Excluded from the test are however the t1B and t1D suites. Also test cases test3 and test4 in t1A as well as the test1 case in t1C are excluded from the test.
Secondly, the test for system t2 should run. The included suites are t2B and t2C. Included are also test cases test4, test1 and test7 in suite t2A. Note that the test cases will be executed in the specified order.
Lastly, all suites for systems t3 are to be completely skipped and this should be explicitly noted in the log files.

It is possible for the user to provide a test specification that includes (for Common Test) unrecognizable terms. If this is desired, the -allow_user_terms flag should be used when starting tests with run_test. This forces Common Test to ignore unrecognizable terms. Note that in this mode, Common Test is not able to check the specification for errors as efficiently as if the scanner runs in default mode. If ct:run_test/1 is used for starting the tests, the relaxed scanner mode is enabled by means of the tuple: {allow_user_terms,true}

6.9 Log files

As the execution of the test suites proceed, events are logged in four different ways:

Text to the operator's console.
Suite related information is sent to the major log file.
Case related information is sent to the minor log file.
The HTML overview log file gets updated with test results.
A link to all runs executed from a certain directory is written in the log named "all_runs.html" and direct links to all tests (the latest results) are written to the top level "index.html".

Typically the operator, who may run hundreds or thousands of test cases, doesn't want to fill the console with details about, or printouts from, the specific test cases. By default, the operator will only see:

A confirmation that the test has started and information about how many test cases will be executed totally.
A small note about each failed test case.
A summary of all the run test cases.
A confirmation that the test run is complete.
Some special information like error reports and progress reports, printouts written with erlang:display/1, or io:format/3 specifically addressed to a receiver other than standard_io (e.g. the default group leader process 'user').

If/when the operator wants to dig deeper into the general results, or the result of a specific test case, he should do so by following the links in the HTML presentation and take a look in the major or minor log files. The "all_runs.html" page is a practical starting point usually. It's located in logdir and contains a link to each test run including a quick overview (date and time, node name, number of tests, test names and test result totals).

An "index.html" page is written for each test run (i.e. stored in the "ct_run" directory tagged with node name, date and time). This file gives a short overview of all individual tests performed in the same test run. The test names follow this convention:

TopLevelDir.TestDir (all suites in TestDir executed)
TopLevelDir.TestDir:suites (specific suites were executed)
TopLevelDir.TestDir.Suite (all cases in Suite executed)
TopLevelDir.TestDir.Suite:cases (specific test cases were executed)
TopLevelDir.TestDir.Suite.Case (only Case was executed)

On the test run index page there is a link to the Common Test 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 very helpful when analyzing test results or debugging test suites.

On the test run index page it is noted if a test has missing suites (i.e. suites that Common Test has failed to compile). Names of the missing suites can be found in the Common Test Framework log file.

The major logfile shows a detailed report of the test run. It includes test suite and test case names, execution time, the exact reason for failures etc. The information is available in both a file with textual and with HTML representation. The HTML file shows a summary which 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.

The minor log file contain full details of every single test case, each one in a separate file. This way the files should be easy to compare with previous test runs, even if the set of test cases change.

Which information goes where is user configurable via the test server controller. Three threshold values determine what comes out on screen, and in the major or minor log files. See the OTP Test Server manual for information. The contents that goes to the HTML log file is fixed however and cannot be altered.

The log files are written continously during a test run and links are always created initially when a test starts. This makes it possible to follow test progress simply by refreshing pages in the HTML browser. Statistics totals are not presented until a test is complete however.

6.10 HTML Style Sheets

Common Test includes the optional feature to use HTML style sheets (CSS) for customizing user printouts. The functions in ct that print to a test case HTML log file (log/3 and pal/3) accept Category as first argument. With this argument it's possible to specify a category 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 may look like this:

<style>
  div.ct_internal { background:lightgrey; color:black }
  div.default     { background:lightgreen; color:black }
  div.sys_config  { background:blue; color:white }
  div.sys_state   { background:yellow; color:black }
  div.error       { background:red; color:white }
</style>

To install the CSS file (Common Test inlines the definition in the HTML code), the name may be provided when executing run_test. Example:

	  $ run_test -dir $TEST/prog -stylesheet $TEST/styles/test_categories.css

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

It is also possible to install style sheets on a per suite and per test case basis. Example:

	  -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).

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 can not be used by other suites. A suite private style sheet, if specified, will be used in favour of a global style sheet (one specified with the -stylesheet flag). A stylesheet tuple (as returned by suite/0 above) can also be returned from a test case info 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 favour of a suite or global level style sheet.

In a tuple {stylesheet,CSSFile}, if CSSFile is specified with a path, e.g. "$TEST/styles/categories.css", this full name will be used to locate the file. If only the file name is specified however, e.g. "categories.css", then the CSS file is assumed to be located in the data directory, data_dir, of the suite. The latter usage is recommended since it is portable compared to hard coding path names in the suite!

The Category argument in the example above may have the value (atom) sys_config (white on blue), sys_state (black on yellow) or error (white on red).

If the Category argument is not specified, Common Test will use the CSS selector div.default for the printout. For this reason a user supplied style sheet must include this selector. Also the selector div.ct_internal must be included. Hence a minimal user style sheet should look like this (which is also the default style sheet Common Test uses if no user CSS file is provided):

	  <style>
	  div.ct_internal { background:lightgrey; color:black }
	  div.default     { background:lightgreen; color:black }
	  </style>

6.11 Repeating tests

You can order Common Test to repeat the tests you specify. You can choose to repeat tests a certain 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 means of time, it is also possible to specify what action Common Test should take upon timeout. Either Common Test performs all tests in the current run before stopping, or it stops as soon as the current test job is finished. Repetition can be activated by means of run_test start flags, or tuples in the ct:run:test/1 option list argument. The flags (options in parenthesis) are:

-repeat N ({repeat,N}), where N is a positive integer.
-duration DurTime ({duration,DurTime}), where DurTime is the duration, see below.
-until StopTime ({until,StopTime}), where StopTime is finish time, see below.
-force_stop ({force_stop,true})

The duration time, DurTime, is specified as HHMMSS. Example: -duration 012030 or {duration,"012030"}, means the tests will be executed and (if time allows) repeated, until timeout occurs after 1 h, 20 min and 30 secs. StopTime can be specified as HHMMSS and is then interpreted as a time today (or possibly tomorrow). StopTime can also be specified as YYMoMoDDHHMMSS. Example: -until 071001120000 or {until,"071001120000"}, which means the tests will be executed and (if time allows) repeated, until 12 o'clock on the 1st of Oct 2007.

When timeout occurs, Common Test will never abort the test run immediately, since this might leave the system under test in an undefined, and possibly bad, state. Instead Common Test will finish the current test job, or the complete test run, before stopping. The latter is the default behaviour. The force_stop flag/option tells Common Test to stop as soon as the current test job is finished. Note that since Common Test always finishes off the current test job or test session, the time specified with duration or until is never definitive!

Log files from every single repeated test run is saved in normal Common Test fashion (see above). Common Test may 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.

Note that for each test run that is part of a repeated session, information about the particular test run is printed in the Common Test Framework Log. There you can read the repetition number, remaining time, etc.

Example 1:

          $ run_test -dir $TEST_ROOT/to1 $TEST_ROOT/to2 -duration 001000 -force_stop

Here the suites in test directory to1, followed by the suites in to2, will be executed in one test run. A timeout event will occur after 10 minutes. As long as there is time left, Common Test will repeat the test run (i.e. starting over with the to1 test). When the timeout occurs, Common Test will stop as soon as the current job is finished (because of the force_stop flag). As a result, the specified test run might be aborted after the to1 test and before the to2 test.

Example 2:

          $ date
	  Fri Sep 28 15:00:00 MEST 2007

          $ run_test -dir $TEST_ROOT/to1 $TEST_ROOT/to2 -until 160000

Here the same test run as in the example above will be executed (and possibly repeated). In this example, however, the timeout will occur after 1 hour and when that happens, Common Test will finish the entire test run before stopping (i.e. the to1 and to2 test will always both be executed in the same test run).

Example 3:

          $ run_test -dir $TEST_ROOT/to1 $TEST_ROOT/to2 -repeat 5

Here the test run, including both the to1 and the to2 test, will be repeated 5 times.

Note

This feature should not be confused with the repeat property of a test case group. The options described here are used to repeat execution of entire test runs, while the repeat 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 the Writing Test Suites chapter.

6.12 Silent Connections

The protocol handling processes in Common Test, implemented by ct_telnet, ct_ftp etc, do verbose printing to the test case logs. This can be switched off by means of the -silent_connections flag:

	run_test -silent_connections [conn_types]

where conn_types specifies telnet, ftp, rpc and/or snmp.

Example:

	run_test ... -silent_connections telnet ftp

switches off logging for telnet and ftp connections.

	run_test ... -silent_connections

switches off logging for all connection types.

Basic and important information such as opening and closing a connection, fatal communication error and reconnection attempts will always be printed even if logging has been suppressed for the connection type in question. However, operations such as sending and receiving data may be performed silently.

It is possible to also specify silent_connections in a test suite. This is accomplished by returning a tuple, {silent_connections,ConnTypes}, in the suite/0 or test case info list. If ConnTypes is a list of atoms (telnet, ftp, rpc and/or snmp), output for any corresponding connections will be suppressed. Full logging is per default enabled for any connection of type not specified in ConnTypes. Hence, if ConnTypes is the empty list, logging is enabled for all connections.

The silent_connections setting returned from a test case info function overrides, for the test case in question, any setting made with suite/0 (which is the setting used for all cases in the suite). Example:

	
	-module(my_SUITE).
	...
	suite() -> [..., {silent_connections,[telnet,ftp]}, ...].
	...
	my_testcase1() ->
	[{silent_connections,[ftp]}].
	my_testcase1(_) ->
	...
	my_testcase2(_) ->
	...

In this example, suite/0 tells Common Test to suppress printouts from telnet and ftp connections. This is valid for all test cases. However, my_testcase1/0 specifies that for this test case, only ftp should be silent. The result is that my_testcase1 will get telnet info (if any) printed in the log, but not ftp info. my_testcase2 will get no info from either connection printed.

The -silent_connections tag (or silent_connections tagged tuple in the call to ct:run_test/1) overrides any settings in the test suite.

Note that in the current Common Test version, the silent_connections feature only works for telnet connections. Support for other connection types will be added in future Common Test versions.