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Testing Erlang/OTP

Before you start testing you need to have the Erlang release which you are going to test in your path. See $ERL_TOP/HOWTO/ for instructions on how to build an Erlang release.

Short version

Move to the top directory of the Erlang release you want to test, i.e. cd /ldisk/work/otp

export ERL_TOP=`pwd`
./otp_build setup -a
export PATH=`pwd`/bin:$PATH
./otp_build tests
cd release/tests/test_server
erl -s ts install -s ts run all_tests -s init stop

Where are the tests

There are a lot of tests which test Erlang/OTP (as of 2012 about 12000) and they are located in different places throughout the source tree. Below is a list of the places where you can expect to find tests:

  • $ERL_TOP/lib/AppName/test/
  • $ERL_TOP/erts/test/
  • $ERL_TOP/erts/emulator/test/
  • $ERL_TOP/erts/epmd/test/

Writing tests

All tests are common_test suites and follow the same pattern as all common_test suites. However, a couple of corner cases are handled by a test wrapper called ts. ts allows the test writer to put Makefile.src and Makefile.first files in the data_dir and a special directory called all_SUITE_data.

Makefile.first is run before any other Makefile and is typically used to generate .hrl files which are needed by other test suites. At the moment only the erl_interface tests use this feature and it should remain that way.

Makefile.src is configured to a Makefile using the variables created when configuring the tests. These Makefiles are later run by the test suite to compile whatever platform specific code the tests need to run.

Releasing tests

If you cannot use ct_run in the source tree you have to release the tests into a common test directory. The easiest way to do this is to use otp_build like this:

export ERL_TOP=`pwd`; ./otp_build tests

This will release all tests in Erlang/OTP to $ERL_TOP/release/tests/. If you want to change the directory where the tests are released to use the TESTROOT environmental variable.

In the $TESTROOT you should now see *_test folders. These folders contain everything needed to test Erlang/OTP and are platform independent; if you are testing Erlang on multiple platforms you just have to release on one and copy the tests to all other platforms.

Releasing cross tests

For releasing tests in a cross compilation environment see $ERL_TOP/HOWTO/

Configuring and Running tests

Running tests is done by first navigating to the $TESTROOT/test_server folder created when you released the tests and then start erl in that directory. The emulator flags specified will be used in the test runs. For example, if you want to test using async threads you have to supply +A 10 to erl when you start it.

To configure and run the tests ts is used. ts is a wrapper module to common_test which takes care of configuration and build issues before common_test is started.

ts has a lot of special options and functions which can be usefull when testing Erlang/OTP. For a full listing issue ts:help() in the erlang shell.

Configuring the test environment

Before running released tests you have to install them on the target system. Installing the tests is done by calling ts:install(). in the Erlang shell which you intend to test from. ts:install() is basically a wrapper to a configure script and some Erlang code which figures out what your system looks like and what kind of emulator you are testing with. ts:install() can also take some arguments if necessary, see ts:help() for details.

All variables created by ts:install() are found in $TESTROOT/test_server/variables.

Running the tests

To run all test suites go to $TESTROOT/test_server fire up an Erlang shell and type:


Note that running all tests will require several hours, so you may want to run the test cases for a single application

ts:run(Application, [batch]).

or even part of the test suite for an application, for example

ts:run(emulator, bs, [batch]).

to run all test suite modules starting with bs (i.e. all modules that test the bit syntax).

To run a specific test case in a module, the full name of the module and test case must be specified:

ts:run(emulator, bs_bincomp_SUITE, byte_aligned, [batch]).

Run ts:help(). for more information.

As of R14B02 it is also possibly to start all tests but the erl_interface tests by invoking Common Test directly from the released applications test directory, i.e.

cd $TESTROOT/test_server
$ERL_TOP/bin/ct_run -suite ../compiler_test/andor_SUITE -case t_orelse

Running ct_run from the command line still requires you to do the ts:install() step above.

Examining the results

Open the file release/tests/test_server/index.html in a web browser. Or open release/tests/test_server/last_test.html when a test suite is running to examine the results so far for the currently executing test suite (in R14B02 and later you want to open the release/tests/test_server/all_runs.html file to get to the currently running test)