The Tor Browser: comparison testing/mozbase/docs/manifestdestiny.rst

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+Managing lists of tests
+=======================
+We don't always want to run all tests, all the time. Sometimes a test
+may be broken, in other cases we only want to run a test on a specific
+platform or build of Mozilla. To handle these cases (and more), we
+created a python library to create and use test "manifests", which
+codify this information.
+:mod:`manifestdestiny` --- Create and manage test manifests
+-----------------------------------------------------------
+manifestdestiny lets you easily create and use test manifests, to
+control which tests are run under what circumstances.
+What ManifestDestiny gives you:
+* manifests are ordered lists of tests
+* tests may have an arbitrary number of key, value pairs
+* the parser returns an ordered list of test data structures, which
+are just dicts with some keys.  For example, a test with no
+user-specified metadata looks like this:
+.. code-block:: text
+[{'expected': 'pass',
+'path': '/home/mozilla/mozmill/src/ManifestDestiny/manifestdestiny/tests/testToolbar/testBackForwardButtons.js',
+'relpath': 'testToolbar/testBackForwardButtons.js',
+'name': 'testBackForwardButtons.js',
+'here': '/home/mozilla/mozmill/src/ManifestDestiny/manifestdestiny/tests',
+'manifest': '/home/mozilla/mozmill/src/ManifestDestiny/manifestdestiny/tests/manifest.ini',}]
+The keys displayed here (path, relpath, name, here, and manifest) are
+reserved keys for ManifestDestiny and any consuming APIs.  You can add
+additional key, value metadata to each test.
+Why have test manifests?
+````````````````````````
+It is desirable to have a unified format for test manifests for testing
+[mozilla-central](http://hg.mozilla.org/mozilla-central), etc.
+* It is desirable to be able to selectively enable or disable tests based on platform or other conditions. This should be easy to do. Currently, since many of the harnesses just crawl directories, there is no effective way of disabling a test except for removal from mozilla-central
+* It is desriable to do this in a universal way so that enabling and disabling tests as well as other tasks are easily accessible to a wider audience than just those intimately familiar with the specific test framework.
+* It is desirable to have other metadata on top of the test. For instance, let's say a test is marked as skipped. It would be nice to give the reason why.
+Most Mozilla test harnesses work by crawling a directory structure.
+While this is straight-forward, manifests offer several practical
+advantages:
+* ability to turn a test off easily: if a test is broken on m-c
+currently, the only way to turn it off, generally speaking, is just
+removing the test.  Often this is undesirable, as if the test should
+be dismissed because other people want to land and it can't be
+investigated in real time (is it a failure? is the test bad? is no
+one around that knows the test?), then backing out a test is at best
+problematic.  With a manifest, a test may be disabled without
+removing it from the tree and a bug filed with the appropriate
+reason:
+.. code-block:: text
+[test_broken.js]
+disabled = https://bugzilla.mozilla.org/show_bug.cgi?id=123456
+* ability to run different (subsets of) tests on different
+platforms. Traditionally, we've done a bit of magic or had the test
+know what platform it would or would not run on. With manifests, you
+can mark what platforms a test will or will not run on and change
+these without changing the test.
+.. code-block:: text
+[test_works_on_windows_only.js]
+run-if = os == 'win'
+* ability to markup tests with metadata. We have a large, complicated,
+and always changing infrastructure.  key, value metadata may be used
+as an annotation to a test and appropriately curated and mined.  For
+instance, we could mark certain tests as randomorange with a bug
+number, if it were desirable.
+* ability to have sane and well-defined test-runs. You can keep
+different manifests for different test runs and ``[include:]``
+(sub)manifests as appropriate to your needs.
+Manifest Format
+````````
+Manifests are .ini file with the section names denoting the path
+relative to the manifest:
+.. code-block:: text
+[foo.js]
+[bar.js]
+[fleem.js]
+The sections are read in order. In addition, tests may include
+arbitrary key, value metadata to be used by the harness.  You may also
+have a `[DEFAULT]` section that will give key, value pairs that will
+be inherited by each test unless overridden:
+.. code-block:: text
+[DEFAULT]
+type = restart
+[lilies.js]
+color = white
+[daffodils.js]
+color = yellow
+type = other
+# override type from DEFAULT
+[roses.js]
+color = red
+You can also include other manifests:
+.. code-block:: text
+[include:subdir/anothermanifest.ini]
+Manifests are included relative to the directory of the manifest with
+the `[include:]` directive unless they are absolute paths.
+By default you can use both '#' and ';' as comment characters. Comments
+must start on a new line, inline comments are not supported.
+.. code-block:: text
+[roses.js]
+# a valid comment
+; another valid comment
+color = red # not a valid comment
+In the example above, the 'color' property will have the value 'red #
+not a valid comment'.
+Manifest Conditional Expressions
+````````````````````````````````
+The conditional expressions used in manifests are parsed using the *ExpressionParser* class.
+.. autoclass:: manifestparser.ExpressionParser
+Consumers of this module are expected to pass in a value dictionary
+for evaluating conditional expressions. A common pattern is to pass
+the dictionary from the :mod:`mozinfo` module.
+Data
+````
+Manifest Destiny gives tests as a list of dictionaries (in python
+terms).
+* path: full path to the test
+* relpath: relative path starting from the root manifest location
+* name: file name of the test
+* here: the parent directory of the manifest
+* manifest: the path to the manifest containing the test
+This data corresponds to a one-line manifest:
+.. code-block:: text
+[testToolbar/testBackForwardButtons.js]
+If additional key, values were specified, they would be in this dict
+as well.
+Outside of the reserved keys, the remaining key, values
+are up to convention to use.  There is a (currently very minimal)
+generic integration layer in ManifestDestiny for use of all harnesses,
+`manifestparser.TestManifest`.
+For instance, if the 'disabled' key is present, you can get the set of
+tests without disabled (various other queries are doable as well).
+Since the system is convention-based, the harnesses may do whatever
+they want with the data.  They may ignore it completely, they may use
+the provided integration layer, or they may provide their own
+integration layer.  This should allow whatever sort of logic is
+desired.  For instance, if in yourtestharness you wanted to run only on
+mondays for a certain class of tests:
+.. code-block:: text
+tests = []
+for test in manifests.tests:
+if 'runOnDay' in test:
+if calendar.day_name[calendar.weekday(*datetime.datetime.now().timetuple()[:3])].lower() == test['runOnDay'].lower():
+tests.append(test)
+else:
+tests.append(test)
+To recap:
+* the manifests allow you to specify test data
+* the parser gives you this data
+* you can use it however you want or process it further as you need
+Tests are denoted by sections in an .ini file (see
+http://hg.mozilla.org/automation/ManifestDestiny/file/tip/manifestdestiny/tests/mozmill-example.ini).
+Additional manifest files may be included with an `[include:]` directive:
+.. code-block:: text
+[include:path-to-additional-file.manifest]
+The path to included files is relative to the current manifest.
+The `[DEFAULT]` section contains variables that all tests inherit from.
+Included files will inherit the top-level variables but may override
+in their own `[DEFAULT]` section.
+ManifestDestiny Architecture
+````````````````````````````
+There is a two- or three-layered approach to the ManifestDestiny
+architecture, depending on your needs:
+1. ManifestParser: this is a generic parser for .ini manifests that
+facilitates the `[include:]` logic and the inheritence of
+metadata. Despite the internal variable being called `self.tests`
+(an oversight), this layer has nothing in particular to do with tests.
+2. TestManifest: this is a harness-agnostic integration layer that is
+test-specific. TestManifest faciliates `skip-if` and `run-if` logic.
+3. Optionally, a harness will have an integration layer than inherits
+from TestManifest if more harness-specific customization is desired at
+the manifest level.
+See the source code at https://github.com/mozilla/mozbase/tree/master/manifestdestiny
+and
+https://github.com/mozilla/mozbase/blob/master/manifestdestiny/manifestparser.py
+in particular.
+Using Manifests
+```````````````
+A test harness will normally call `TestManifest.active_tests`:
+.. code-block:: text
+def active_tests(self, exists=True, disabled=True, **tags):
+The manifests are passed to the `__init__` or `read` methods with
+appropriate arguments.  `active_tests` then allows you to select the
+tests you want:
+- exists : return only existing tests
+- disabled : whether to return disabled tests; if not these will be
+filtered out; if True (the default), the `disabled` key of a
+test's metadata will be present and will be set to the reason that a
+test is disabled
+- tags : keys and values to filter on (e.g. `os='linux'`)
+`active_tests` looks for tests with `skip-if`
+`run-if`.  If the condition is or is not fulfilled,
+respectively, the test is marked as disabled.  For instance, if you
+pass `**dict(os='linux')` as `**tags`, if a test contains a line
+`skip-if = os == 'linux'` this test will be disabled, or
+`run-if = os = 'win'` in which case the test will also be disabled.  It
+is up to the harness to pass in tags appropriate to its usage.
+Creating Manifests
+``````````````````
+ManifestDestiny comes with a console script, `manifestparser create`, that
+may be used to create a seed manifest structure from a directory of
+files.  Run `manifestparser help create` for usage information.
+Copying Manifests
+`````````````````
+To copy tests and manifests from a source:
+.. code-block:: text
+manifestparser [options] copy from_manifest to_directory -tag1 -tag2 `key1=value1 key2=value2 ...
+Updating Tests
+``````````````
+To update the tests associated with with a manifest from a source
+directory:
+.. code-block:: text
+manifestparser [options] update manifest from_directory -tag1 -tag2 `key1=value1 `key2=value2 ...
+Usage example
+`````````````
+Here is an example of how to create manifests for a directory tree and
+update the tests listed in the manifests from an external source.
+Creating Manifests
+``````````````````
+Let's say you want to make a series of manifests for a given directory structure containing `.js` test files:
+.. code-block:: text
+testing/mozmill/tests/firefox/
+testing/mozmill/tests/firefox/testAwesomeBar/
+testing/mozmill/tests/firefox/testPreferences/
+testing/mozmill/tests/firefox/testPrivateBrowsing/
+testing/mozmill/tests/firefox/testSessionStore/
+testing/mozmill/tests/firefox/testTechnicalTools/
+testing/mozmill/tests/firefox/testToolbar/
+testing/mozmill/tests/firefox/restartTests
+You can use `manifestparser create` to do this:
+.. code-block:: text
+$ manifestparser help create
+Usage: manifestparser.py [options] create directory <directory> <...>
+create a manifest from a list of directories
+Options:
+-p PATTERN, `pattern=PATTERN
+glob pattern for files
+-i IGNORE, `ignore=IGNORE
+directories to ignore
+-w IN_PLACE, --in-place=IN_PLACE
+Write .ini files in place; filename to write to
+We only want `.js` files and we want to skip the `restartTests` directory.
+We also want to write a manifest per directory, so I use the `--in-place`
+option to write the manifests:
+.. code-block:: text
+manifestparser create . -i restartTests -p '*.js' -w manifest.ini
+This creates a manifest.ini per directory that we care about with the JS test files:
+.. code-block:: text
+testing/mozmill/tests/firefox/manifest.ini
+testing/mozmill/tests/firefox/testAwesomeBar/manifest.ini
+testing/mozmill/tests/firefox/testPreferences/manifest.ini
+testing/mozmill/tests/firefox/testPrivateBrowsing/manifest.ini
+testing/mozmill/tests/firefox/testSessionStore/manifest.ini
+testing/mozmill/tests/firefox/testTechnicalTools/manifest.ini
+testing/mozmill/tests/firefox/testToolbar/manifest.ini
+The top-level `manifest.ini` merely has `[include:]` references to the sub manifests:
+.. code-block:: text
+[include:testAwesomeBar/manifest.ini]
+[include:testPreferences/manifest.ini]
+[include:testPrivateBrowsing/manifest.ini]
+[include:testSessionStore/manifest.ini]
+[include:testTechnicalTools/manifest.ini]
+[include:testToolbar/manifest.ini]
+Each sub-level manifest contains the (`.js`) test files relative to it.
+Updating the tests from manifests
+`````````````````````````````````
+You may need to update tests as given in manifests from a different source directory.
+`manifestparser update` was made for just this purpose:
+.. code-block:: text
+Usage: manifestparser [options] update manifest directory -tag1 -tag2 `key1=value1 --key2=value2 ...
+update the tests as listed in a manifest from a directory
+To update from a directory of tests in `~/mozmill/src/mozmill-tests/firefox/` run:
+.. code-block:: text
+manifestparser update manifest.ini ~/mozmill/src/mozmill-tests/firefox/
+Tests
+`````
+ManifestDestiny includes a suite of tests:
+https://github.com/mozilla/mozbase/tree/master/manifestdestiny/tests
+`test_manifest.txt` is a doctest that may be helpful in figuring out
+how to use the API.  Tests are run via `python test.py`.
+Bugs
+````
+Please file any bugs or feature requests at
+https://bugzilla.mozilla.org/enter_bug.cgi?product=Testing&component=ManifestParser
+Or contact jhammel @mozilla.org or in #ateam on irc.mozilla.org
+CLI
+```
+Run `manifestparser help` for usage information.
+To create a manifest from a set of directories:
+.. code-block:: text
+manifestparser [options] create directory <directory> <...> [create-options]
+To output a manifest of tests:
+.. code-block:: text
+manifestparser [options] write manifest <manifest> <...> -tag1 -tag2 --key1=value1 --key2=value2 ...
+To copy tests and manifests from a source:
+.. code-block:: text
+manifestparser [options] copy from_manifest to_manifest -tag1 -tag2 `key1=value1 key2=value2 ...
+To update the tests associated with with a manifest from a source
+directory:
+.. code-block:: text
+manifestparser [options] update manifest from_directory -tag1 -tag2 --key1=value1 --key2=value2 ...
+Design Considerations
+`````````````````````
+Contrary to some opinion, manifestparser.py and the associated .ini
+format were not magically plucked from the sky but were descended upon
+through several design considerations.
+* test manifests should be ordered.  While python 2.6 and greater has
+a ConfigParser that can use an ordered dictionary, it is a
+requirement that we support python 2.4 for the build + testing
+environment.  To that end, a `read_ini` function was implemented
+in manifestparser.py that should be the equivalent of the .ini
+dialect used by ConfigParser.
+* the manifest format should be easily human readable/writable.  While
+there was initially some thought of using JSON, there was pushback
+that JSON was not easily editable.  An ideal manifest format would
+degenerate to a line-separated list of files.  While .ini format
+requires an additional `[]` per line, and while there have been
+complaints about this, hopefully this is good enough.
+* python does not have an in-built YAML parser.  Since it was
+undesirable for manifestparser.py to have any dependencies, YAML was
+dismissed as a format.
+* we could have used a proprietary format but decided against it.
+Everyone knows .ini and there are good tools to deal with it.
+However, since read_ini is the only function that transforms a
+manifest to a list of key, value pairs, while the implications for
+changing the format impacts downstream code, doing so should be
+programmatically simple.
+* there should be a single file that may easily be
+transported. Traditionally, test harnesses have lived in
+mozilla-central. This is less true these days and it is increasingly
+likely that more tests will not live in mozilla-central going
+forward.  So `manifestparser.py` should be highly consumable. To
+this end, it is a single file, as appropriate to mozilla-central,
+which is also a working python package deployed to PyPI for easy
+installation.
+Historical Reference
+````````````````````
+Date-ordered list of links about how manifests came to be where they are today::
+* https://wiki.mozilla.org/Auto-tools/Projects/UniversalManifest
+* http://alice.nodelman.net/blog/post/2010/05/
+* http://alice.nodelman.net/blog/post/universal-manifest-for-unit-tests-a-proposal/
+* https://elvis314.wordpress.com/2010/07/05/improving-personal-hygiene-by-adjusting-mochitests/
+* https://elvis314.wordpress.com/2010/07/27/types-of-data-we-care-about-in-a-manifest/
+* https://bugzilla.mozilla.org/show_bug.cgi?id=585106
+* http://elvis314.wordpress.com/2011/05/20/converting-xpcshell-from-listing-directories-to-a-manifest/
+* https://bugzilla.mozilla.org/show_bug.cgi?id=616999
+* https://developer.mozilla.org/en/Writing_xpcshell-based_unit_tests#Adding_your_tests_to_the_xpcshell_manifest

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testing/mozbase/docs/manifestdestiny.rst