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diff --git a/testing/docs/xpcshell/index.rst b/testing/docs/xpcshell/index.rst new file mode 100644 index 0000000000..e9a8e93aca --- /dev/null +++ b/testing/docs/xpcshell/index.rst @@ -0,0 +1,822 @@ +XPCShell tests +============== + +xpcshell tests are quick-to-run tests, that are generally used to write +unit tests. They do not have access to the full browser chrome like +``browser chrome tests``, and so have much +lower overhead. They are typical run by using ``./mach xpcshell-test`` +which initiates a new ``xpcshell`` session with +the xpcshell testing harness. Anything available to the XPCOM layer +(through scriptable interfaces) can be tested with xpcshell. See +``Mozilla automated testing`` and ``pages +tagged "automated testing"`` for more +information. + +Introducing xpcshell testing +---------------------------- + +xpcshell test filenames must start with ``test_``. + +Creating a new test directory +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +If you need to create a new test directory, then follow the steps here. +The test runner needs to know about the existence of the tests and how +to configure them through the use of the ``xpcshell.ini`` manifest file. + +First add a ``XPCSHELL_TESTS_MANIFESTS += ['xpcshell.ini']`` declaration +(with the correct relative ``xpcshell.ini`` path) to the ``moz.build`` +file located in or above the directory. + +Then create an empty ``xpcshell.ini`` file to tell the build system +about the individual tests, and provide any additional configuration +options. + +Creating a new test in an existing directory +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +If you're creating a new test in an existing directory, you can simply +run: + +.. code:: bash + + $ ./mach addtest path/to/test/test_example.js + $ hg add path/to/test/test_example.js + +This will automatically create the test file and add it to +``xpcshell.ini``, the second line adds it to your commit. + +The test file contains an empty test which will give you an idea of how +to write a test. There are plenty more examples throughout +mozilla-central. + +Running tests +------------- + +To run the test, execute it by running the ``mach`` command from the +root of the Gecko source code directory. + +.. code:: bash + + # Run a single test: + $ ./mach xpcshell-test path/to/tests/test_example.js + + # Test an entire test suite in a folder: + $ ./mach xpcshell-test path/to/tests/ + + # Or run any type of test, including both xpcshell and browser chrome tests: + $ ./mach test path/to/tests/test_example.js + +The test is executed by the testing harness. It will call in turn: + +- ``run_test`` (if it exists). +- Any functions added with ``add_task`` or ``add_test`` in the order + they were defined in the file. + +See also the notes below around ``add_task`` and ``add_test``. + +xpcshell Testing API +-------------------- + +xpcshell tests have access to the following functions. They are defined +in +:searchfox:`testing/xpcshell/head.js <testing/xpcshell/head.js>` +and +:searchfox:`testing/modules/Assert.sys.mjs <testing/modules/Assert.sys.mjs>`. + +Assertions +^^^^^^^^^^ + +- ``Assert.ok(truthyOrFalsy[, message])`` +- ``Assert.equal(actual, expected[, message])`` +- ``Assert.notEqual(actual, expected[, message])`` +- ``Assert.deepEqual(actual, expected[, message])`` +- ``Assert.notDeepEqual(actual, expected[, message])`` +- ``Assert.strictEqual(actual, expected[, message])`` +- ``Assert.notStrictEqual(actual, expected[, message])`` +- ``Assert.rejects(actual, expected[, message])`` +- ``Assert.greater(actual, expected[, message])`` +- ``Assert.greaterOrEqual(actual, expected[, message])`` +- ``Assert.less(actual, expected[, message])`` +- ``Assert.lessOrEqual(actual, expected[, message])`` + + +These assertion methods are provided by +:searchfox:`testing/modules/Assert.sys.mjs <testing/modules/Assert.sys.mjs>`. +It implements the `CommonJS Unit Testing specification version +1.1 <http://wiki.commonjs.org/wiki/Unit_Testing/1.1>`__, which +provides a basic, standardized interface for performing in-code +logical assertions with optional, customizable error reporting. It is +*highly* recommended to use these assertion methods, instead of the +ones mentioned below. You can on all these methods remove the +``Assert.`` from the beginning of the name, e.g. ``ok(true)`` rather +than ``Assert.ok(true)``, however keeping the ``Assert.`` prefix may +be seen as more descriptive and easier to spot where the tests are. +``Assert.throws(callback, expectedException[, message])`` +``Assert.throws(callback[, message])`` +Asserts that the provided callback function throws an exception. The +``expectedException`` argument can be an ``Error`` instance, or a +regular expression matching part of the error message (like in +``Assert.throws(() => a.b, /is not defined/``). +``Assert.rejects(promise, expectedException[, message])`` +Asserts that the provided promise is rejected. Note: that this should +be called prefixed with an ``await``. The ``expectedException`` +argument can be an ``Error`` instance, or a regular expression +matching part of the error message. Example: +``await Assert.rejects(myPromise, /bad response/);`` + +Test case registration and execution +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +``add_task([condition, ]testFunc)`` + Add an asynchronous function or to the list of tests that are to be + run asynchronously. Whenever the function ``await``\ s a + `Promise </en-US/docs/Mozilla/JavaScript_code_modules/Promise.jsm>`__, + the test runner waits until the promise is resolved or rejected + before proceeding. Rejected promises are converted into exceptions, + and resolved promises are converted into values. + You can optionally specify a condition which causes the test function + to be skipped; see `Adding conditions through the add_task or + add_test + function <#adding-conditions-through-the-add-task-or-add-test-function>`__ + for details. + For tests that use ``add_task()``, the ``run_test()`` function is + optional, but if present, it should also call ``run_next_test()`` to + start execution of all asynchronous test functions. The test cases + must not call ``run_next_test()``, it is called automatically when + the task finishes. See `Async tests <#async-tests>`__, below, for + more information. +``add_test([condition, ]testFunction)`` + Add a test function to the list of tests that are to be run + asynchronously. + You can optionally specify a condition which causes the test function + to be skipped; see `Adding conditions through the add_task or + add_test + function <#adding-conditions-through-the-add-task-or-add-test-function>`__ + for details. + Each test function must call ``run_next_test()`` when it's done. For + tests that use ``add_test()``, ``the run_test()`` function is + optional, but if present, it should also call ``run_next_test()`` to + start execution of all asynchronous test functions. In most cases, + you should rather use the more readable variant ``add_task()``. See + `Async tests <#async-tests>`__, below, for more information. +``run_next_test()`` + Run the next test function from the list of asynchronous tests. Each + test function must call ``run_next_test()`` when it's done. + ``run_test()`` should also call ``run_next_test()`` to start + execution of all asynchronous test functions. See `Async + tests <#async-tests>`__, below, for more information. +**``registerCleanupFunction``**\ ``(callback)`` + Executes the function ``callback`` after the current JS test file has + finished running, regardless of whether the tests inside it pass or + fail. You can use this to clean up anything that might otherwise + cause problems between test runs. + If ``callback`` returns a ``Promise``, the test will not finish until + the promise is fulfilled or rejected (making the termination function + asynchronous). + Cleanup functions are called in reverse order of registration. +``do_test_pending()`` + Delay exit of the test until do_test_finished() is called. + do_test_pending() may be called multiple times, and + do_test_finished() must be paired with each before the unit test will + exit. +``do_test_finished()`` + Call this function to inform the test framework that an asynchronous + operation has completed. If all asynchronous operations have + completed (i.e., every do_test_pending() has been matched with a + do_test_finished() in execution), then the unit test will exit. + +Environment +^^^^^^^^^^^ + +``do_get_file(testdirRelativePath, allowNonexistent)`` + Returns an ``nsILocalFile`` object representing the given file (or + directory) in the test directory. For example, if your test is + unit/test_something.js, and you need to access unit/data/somefile, + you would call ``do_get_file('data/somefile')``. The given path must + be delimited with forward slashes. You can use this to access + test-specific auxiliary files if your test requires access to + external files. Note that you can also use this function to get + directories. + + .. note:: + + **Note:** If your test needs access to one or more files that + aren't in the test directory, you should install those files to + the test directory in the Makefile where you specify + ``XPCSHELL_TESTS``. For an example, see + ``netwerk/test/Makefile.in#117``. +``do_get_profile()`` + Registers a directory with the profile service and returns an + ``nsILocalFile`` object representing that directory. It also makes + sure that the **profile-change-net-teardown**, + **profile-change-teardown**, and **profile-before-change** `observer + notifications </en/Observer_Notifications#Application_shutdown>`__ + are sent before the test finishes. This is useful if the components + loaded in the test observe them to do cleanup on shutdown (e.g., + places). + + .. note:: + + **Note:** ``do_register_cleanup`` will perform any cleanup + operation *before* the profile and the network is shut down by the + observer notifications. +``do_get_idle()`` + By default xpcshell tests will disable the idle service, so that idle + time will always be reported as 0. Calling this function will + re-enable the service and return a handle to it; the idle time will + then be correctly requested to the underlying OS. The idle-daily + notification could be fired when requesting idle service. It is + suggested to always get the service through this method if the test + has to use idle. +``do_get_cwd()`` + Returns an ``nsILocalFile`` object representing the test directory. + This is the directory containing the test file when it is currently + being run. Your test can write to this directory as well as read any + files located alongside your test. Your test should be careful to + ensure that it will not fail if a file it intends to write already + exists, however. +``load(testdirRelativePath)`` + Imports the JavaScript file referenced by ``testdirRelativePath`` + into the global script context, executing the code inside it. The + file specified is a file within the test directory. For example, if + your test is unit/test_something.js and you have another file + unit/extra_helpers.js, you can load the second file from the first by + calling ``load('extra_helpers.js')``. + +Utility +^^^^^^^ + +``do_parse_document(path, type)`` + Parses and returns a DOM document. +``executeSoon(callback)`` + Executes the function ``callback`` on a later pass through the event + loop. Use this when you want some code to execute after the current + function has finished executing, but you don't care about a specific + time delay. This function will automatically insert a + ``do_test_pending`` / ``do_test_finished`` pair for you. +``do_timeout(delay, fun)`` + Call this function to schedule a timeout. The given function will be + called with no arguments provided after the specified delay (in + milliseconds). Note that you must call ``do_test_pending`` so that + the test isn't completed before your timer fires, and you must call + ``do_test_finished`` when the actions you perform in the timeout + complete, if you have no other functionality to test. (Note: the + function argument used to be a string argument to be passed to eval, + and some older branches support only a string argument or support + both string and function.) + +Multiprocess communication +^^^^^^^^^^^^^^^^^^^^^^^^^^ + +``do_send_remote_message(name, optionalData)`` + Asynchronously send a message to all remote processes. Pairs with + ``do_await_remote_message`` or equivalent ProcessMessageManager + listeners. +``do_await_remote_message(name, optionalCallback)`` + Returns a promise that is resolved when the message is received. Must + be paired with\ ``do_send_remote_message`` or equivalent + ProcessMessageManager calls. If **optionalCallback** is provided, the + callback must call ``do_test_finished``. If optionalData is passed + to ``do_send_remote_message`` then that data is the first argument to + **optionalCallback** or the value to which the promise resolves. + + +xpcshell.ini manifest +--------------------- + +The manifest controls what tests are included in a test suite, and the +configuration of the tests. It is loaded via the \`moz.build\` property +configuration property. + +The following are all of the configuration options for a test suite as +listed under the ``[DEFAULT]`` section of the manifest. + +``tags`` + Tests can be filtered by tags when running multiple tests. The + command for mach is ``./mach xpcshell-test --tag TAGNAME`` +``head`` + The relative path to the head JavaScript file, which is run once + before a test suite is run. The variables declared in the root scope + are available as globals in the test files. See `Test head and + support files <#test-head-and-support-files>`__ for more information + and usage. +``firefox-appdir`` + Set this to "browser" if your tests need access to things in the + browser/ directory (e.g. additional XPCOM services that live there) +``skip-if`` ``run-if`` ``fail-if`` + For this entire test suite, run the tests only if they meet certain + conditions. See `Adding conditions in the xpcshell.ini + manifest <#adding-conditions-through-the-add-task-or-add-test-function>`__ for how + to use these properties. +``support-files`` + Make files available via the ``resource://test/[filename]`` path to + the tests. The path can be relative to other directories, but it will + be served only with the filename. See `Test head and support + files <#test-head-and-support-files>`__ for more information and + usage. +``[test_*]`` + Test file names must start with ``test_`` and are listed in square + brackets + + +Creating a new xpcshell.ini file +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +When creating a new directory and new xpcshell.ini manifest file, the +following must be added to a moz.build file near that file in the +directory hierarchy: + +.. code:: bash + + XPCSHELL_TESTS_MANIFESTS += ['path/to/xpcshell.ini'] + +Typically, the moz.build containing *XPCSHELL_TESTS_MANIFESTS* is not in +the same directory as *xpcshell.ini*, but rather in a parent directory. +Common directory structures look like: + +.. code:: bash + + feature + ├──moz.build + └──tests/xpcshell + └──xpcshell.ini + + # or + + feature + ├──moz.build + └──tests + ├──moz.build + └──xpcshell + └──xpcshell.ini + + +Test head and support files +^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +Typically in a test suite, similar setup code and dependencies will need +to be loaded in across each test. This can be done through the test +head, which is the file declared in the ``xpcshell.ini`` manifest file +under the ``head`` property. The file itself is typically called +``head.js``. Any variable declared in the test head will be in the +global scope of each test in that test suite. + +In addition to the test head, other support files can be declared in the +``xpcshell.ini`` manifest file. This is done through the +``support-files`` declaration. These files will be made available +through the url ``resource://test`` plus the name of the file. These +files can then be loaded in using the +``ChromeUtils.import`` function +or other loaders. The support files can be located in other directory as +well, and they will be made available by their filename. + +.. code:: bash + + # File structure: + + path/to/tests + ├──head.js + ├──module.jsm + ├──moz.build + ├──test_example.js + └──xpcshell.ini + +.. code:: ini + + # xpcshell.ini + [DEFAULT] + head = head.js + support-files = + ./module.jsm + ../../some/other/file.js + [test_component_state.js] + +.. code:: js + + // head.js + var globalValue = "A global value."; + + // Import support-files. + const { foo } = ChromeUtils.import("resource://test/module.jsm"); + const { bar } = ChromeUtils.import("resource://test/file.jsm"); + +.. code:: js + + // test_example.js + function run_test() { + equal(globalValue, "A global value.", "Declarations in head.js can be accessed"); + } + + +Additional testing considerations +--------------------------------- + +Async tests +^^^^^^^^^^^ + +Asynchronous tests (that is, those whose success cannot be determined +until after ``run_test`` finishes) can be written in a variety of ways. + +Task-based asynchronous tests +----------------------------- + +The easiest is using the ``add_task`` helper. ``add_task`` can take an +asynchronous function as a parameter. ``add_task`` tests are run +automatically if you don't have a ``run_test`` function. + +.. code:: js + + add_task(async function test_foo() { + let foo = await makeFoo(); // makeFoo() returns a Promise<foo> + equal(foo, expectedFoo, "Should have received the expected object"); + }); + + add_task(async function test_bar() { + let foo = await makeBar(); // makeBar() returns a Promise<bar> + Assert.equal(bar, expectedBar, "Should have received the expected object"); + }); + +Callback-based asynchronous tests +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +You can also use ``add_test``, which takes a function and adds it to the +list of asynchronously-run functions. Each function given to +``add_test`` must also call ``run_next_test`` at its end. You should +normally use ``add_task`` instead of ``add_test``, but you may see +``add_test`` in existing tests. + +.. code:: js + + add_test(function test_foo() { + makeFoo(function callback(foo) { // makeFoo invokes a callback<foo> once completed + equal(foo, expectedFoo); + run_next_test(); + }); + }); + + add_test(function test_bar() { + makeBar(function callback(bar) { + equal(bar, expectedBar); + run_next_test(); + }); + }); + + +Other tests +^^^^^^^^^^^ + +We can also tell the test harness not to kill the test process once +``run_test()`` is finished, but to keep spinning the event loop until +our callbacks have been called and our test has completed. Newer tests +prefer the use of ``add_task`` rather than this method. This can be +achieved with ``do_test_pending()`` and ``do_test_finished()``: + +.. code:: js + + function run_test() { + // Tell the harness to keep spinning the event loop at least + // until the next do_test_finished() call. + do_test_pending(); + + someAsyncProcess(function callback(result) { + equal(result, expectedResult); + + // Close previous do_test_pending() call. + do_test_finished(); + }); + } + + +Testing in child processeses +^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +By default xpcshell tests run in the parent process. If you wish to run +test logic in the child, you have several ways to do it: + +#. Create a regular test_foo.js test, and then write a wrapper + test_foo_wrap.js file that uses the ``run_test_in_child()`` function + to run an entire script file in the child. This is an easy way to + arrange for a test to be run twice, once in chrome and then later + (via the \_wrap.js file) in content. See /network/test/unit_ipc for + examples. The ``run_test_in_child()`` function takes a callback, so + you should be able to call it multiple times with different files, if + that's useful. +#. For tests that need to run logic in both the parent + child processes + during a single test run, you may use the poorly documented + ``sendCommand()`` function, which takes a code string to be executed + on the child, and a callback function to be run on the parent when it + has completed. You will want to first call + do_load_child_test_harness() to set up a reasonable test environment + on the child. ``sendCommand`` returns immediately, so you will + generally want to use ``do_test_pending``/``do_test_finished`` with + it. NOTE: this method of test has not been used much, and your level + of pain may be significant. Consider option #1 if possible. + +See the documentation for ``run_test_in_child()`` and +``do_load_child_test_harness()`` in testing/xpcshell/head.js for more +information. + + +Platform-specific tests +^^^^^^^^^^^^^^^^^^^^^^^ + +Sometimes you might want a test to know what platform it's running on +(to test platform-specific features, or allow different behaviors). Unit +tests are not normally invoked from a Makefile (unlike Mochitests), or +preprocessed (so not #ifdefs), so platform detection with those methods +isn't trivial. + + +Runtime detection +^^^^^^^^^^^^^^^^^ + +Some tests will want to only execute certain portions on specific +platforms. Use +`AppConstants.jsm <https://searchfox.org/mozilla-central/rev/a0333927deabfe980094a14d0549b589f34cbe49/toolkit/modules/AppConstants.jsm#148>`__ +for determining the platform, for example: + +.. code:: js + + ChromeUtils.import("resource://gre/modules/AppConstants.jsm"); + + let isMac = AppConstants.platform == "macosx"; + + +Conditionally running a test +---------------------------- + +There are two different ways to conditional skip a test, either through + + +Adding conditions through the ``add_task`` or ``add_test`` function +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +You can use conditionals on individual test functions instead of entire +files. The condition is provided as an optional first parameter passed +into ``add_task()`` or ``add_test()``. The condition is an object which +contains a function named ``skip_if()``, which is an `arrow +function </en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions>`__ +returning a boolean value which is **``true``** if the test should be +skipped. + +For example, you can provide a test which only runs on Mac OS X like +this: + +.. code:: js + + ChromeUtils.import("resource://gre/modules/AppConstants.jsm"); + + add_task({ + skip_if: () => AppConstants.platform != "mac" + }, async function some_test() { + // Test code goes here + }); + +Since ``AppConstants.platform != "mac"`` is ``true`` only when testing +on Mac OS X, the test will be skipped on all other platforms. + +.. note:: + + **Note:** Arrow functions are ideal here because if your condition + compares constants, it will already have been evaluated before the + test is even run, meaning your output will not be able to show the + specifics of what the condition is. + + +Adding conditions in the xpcshell.ini manifest +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +Sometimes you may want to add conditions to specify that a test should +be skipped in certain configurations, or that a test is known to fail on +certain platforms. You can do this in xpcshell manifests by adding +annotations below the test file entry in the manifest, for example: + +.. code:: ini + + [test_example.js] + skip-if = os == 'win' + +This example would skip running ``test_example.js`` on Windows. + +.. note:: + + **Note:** Starting with Gecko (Firefox 40 / Thunderbird 40 / + SeaMonkey 2.37), you can use conditionals on individual test + functions instead of on entire files. See `Adding conditions through + the add_task or add_test + function <#adding-conditions-through-the-add-task-or-add-test-function>`__ + above for details. + +There are currently four conditionals you can specify: + +skip-if +""""""" + +``skip-if`` tells the harness to skip running this test if the condition +evaluates to true. You should use this only if the test has no meaning +on a certain platform, or causes undue problems like hanging the test +suite for a long time. + +run-if +'''''' + +``run-if`` tells the harness to only run this test if the condition +evaluates to true. It functions as the inverse of ``skip-if``. + +fail-if +""""""" + +``fail-if`` tells the harness that this test is expected to fail if the +condition is true. If you add this to a test, make sure you file a bug +on the failure and include the bug number in a comment in the manifest, +like: + +.. code:: ini + + [test_example.js] + # bug xxxxxx + fail-if = os == 'linux' + +run-sequentially +"""""""""""""""" + +``run-sequentially``\ basically tells the harness to run the respective +test in isolation. This is required for tests that are not +"thread-safe". You should do all you can to avoid using this option, +since this will kill performance. However, we understand that there are +some cases where this is imperative, so we made this option available. +If you add this to a test, make sure you specify a reason and possibly +even a bug number, like: + +.. code:: ini + + [test_example.js] + run-sequentially = Has to launch Firefox binary, bug 123456. + + +Manifest conditional expressions +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +For a more detailed description of the syntax of the conditional +expressions, as well as what variables are available, `see this +page </en/XPCshell_Test_Manifest_Expressions`. + + +Running a specific test only +---------------------------- + +When working on a specific feature or issue, it is convenient to only +run a specific task from a whole test suite. Use ``.only()`` for that +purpose: + +.. code:: js + + add_task(async function some_test() { + // Some test. + }); + + add_task(async function some_interesting_test() { + // Only this test will be executed. + }).only(); + + +Problems with pending events and shutdown +----------------------------------------- + +Events are not processed during test execution if not explicitly +triggered. This sometimes causes issues during shutdown, when code is +run that expects previously created events to have been already +processed. In such cases, this code at the end of a test can help: + +.. code:: js + + let thread = gThreadManager.currentThread; + while (thread.hasPendingEvents()) + thread.processNextEvent(true); + + +Debugging xpcshell-tests +------------------------ + + +Running unit tests under the javascript debugger +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + + +Via --jsdebugger +^^^^^^^^^^^^^^^^ + +You can specify flags when issuing the ``xpcshell-test`` command that +will cause your test to stop right before running so you can attach the +`javascript debugger </docs/Tools/Tools_Toolbox>`__. + +Example: + +.. code:: bash + + $ ./mach xpcshell-test --jsdebugger browser/components/tests/unit/test_browserGlue_pingcentre.js + 0:00.50 INFO Running tests sequentially. + ... + 0:00.68 INFO "" + 0:00.68 INFO "*******************************************************************" + 0:00.68 INFO "Waiting for the debugger to connect on port 6000" + 0:00.68 INFO "" + 0:00.68 INFO "To connect the debugger, open a Firefox instance, select 'Connect'" + 0:00.68 INFO "from the Developer menu and specify the port as 6000" + 0:00.68 INFO "*******************************************************************" + 0:00.68 INFO "" + 0:00.71 INFO "Still waiting for debugger to connect..." + ... + +At this stage in a running Firefox instance: + +- Go to the three-bar menu, then select ``More tools`` -> + ``Remote Debugging`` +- A new tab is opened. In the Network Location box, enter + ``localhost:6000`` and select ``Connect`` +- You should then get a link to *``Main Process``*, click it and the + Developer Tools debugger window will open. +- It will be paused at the start of the test, so you can add + breakpoints, or start running as appropriate. + +If you get a message such as: + +:: + + 0:00.62 ERROR Failed to initialize debugging: Error: resource://devtools appears to be inaccessible from the xpcshell environment. + This can usually be resolved by adding: + firefox-appdir = browser + to the xpcshell.ini manifest. + It is possible for this to alter test behevior by triggering additional browser code to run, so check test behavior after making this change. + +This is typically a test in core code. You can attempt to add that to +the xpcshell.ini, however as it says, it might affect how the test runs +and cause failures. Generally the firefox-appdir should only be left in +xpcshell.ini for tests that are in the browser/ directory, or are +Firefox-only. + + +Running unit tests under a C++ debugger +--------------------------------------- + + +Via ``--debugger and -debugger-interactive`` +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +You can specify flags when issuing the ``xpcshell-test`` command that +will launch xpcshell in the specified debugger (implemented in +`bug 382682 <https://bugzilla.mozilla.org/show_bug.cgi?id=382682>`__). +Provide the full path to the debugger, or ensure that the named debugger +is in your system PATH. + +Example: + +.. code:: bash + + $ ./mach xpcshell-test --debugger gdb --debugger-interactive netwerk/test/unit/test_resumable_channel.js + # js>_execute_test(); + ...failure or success messages are printed to the console... + # js>quit(); + +On Windows with the VS debugger: + +.. code:: bash + + $ ./mach xpcshell-test --debugger devenv --debugger-interactive netwerk/test/test_resumable_channel.js + +Or with WinDBG: + +.. code:: bash + + $ ./mach xpcshell-test --debugger windbg --debugger-interactive netwerk/test/test_resumable_channel.js + +Or with modern WinDbg (WinDbg Preview as of April 2020): + +.. code:: bash + + $ ./mach xpcshell-test --debugger WinDbgX --debugger-interactive netwerk/test/test_resumable_channel.js + + +Debugging xpcshell tests in a child process +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +To debug the child process, where code is often being run in a project, +set MOZ_DEBUG_CHILD_PROCESS=1 in your environment (or on the command +line) and run the test. You will see the child process emit a printf +with its process ID, then sleep. Attach a debugger to the child's pid, +and when it wakes up you can debug it: + +.. code:: bash + + $ MOZ_DEBUG_CHILD_PROCESS=1 ./mach xpcshell-test test_simple_wrap.js + CHILDCHILDCHILDCHILD + debug me @13476 + + +Debug both parent and child processes +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +Use MOZ_DEBUG_CHILD_PROCESS=1 to attach debuggers to each process. (For +gdb at least, this means running separate copies of gdb, one for each +process.) |