Add m-esr52 at 52.6.0

1 files changed, 831 insertions, 0 deletions

diff --git a/testing/mach_commands.py b/testing/mach_commands.py
new file mode 100644
index 000000000..866bc530c
--- /dev/null
+++ b/testing/mach_commands.py
@@ -0,0 +1,831 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from __future__ import absolute_import, print_function, unicode_literals
+
+import json
+import os
+import sys
+import tempfile
+import subprocess
+import shutil
+from collections import defaultdict
+
+from mach.decorators import (
+    CommandArgument,
+    CommandProvider,
+    Command,
+)
+
+from mozbuild.base import MachCommandBase
+from mozbuild.base import MachCommandConditions as conditions
+import mozpack.path as mozpath
+from argparse import ArgumentParser
+
+UNKNOWN_TEST = '''
+I was unable to find tests from the given argument(s).
+
+You should specify a test directory, filename, test suite name, or
+abbreviation. If no arguments are given, there must be local file
+changes and corresponding IMPACTED_TESTS annotations in moz.build
+files relevant to those files.
+
+It's possible my little brain doesn't know about the type of test you are
+trying to execute. If you suspect this, please request support by filing
+a bug at
+https://bugzilla.mozilla.org/enter_bug.cgi?product=Testing&component=General.
+'''.strip()
+
+UNKNOWN_FLAVOR = '''
+I know you are trying to run a %s test. Unfortunately, I can't run those
+tests yet. Sorry!
+'''.strip()
+
+MOCHITEST_CHUNK_BY_DIR = 4
+MOCHITEST_TOTAL_CHUNKS = 5
+
+TEST_SUITES = {
+    'cppunittest': {
+        'aliases': ('Cpp', 'cpp'),
+        'mach_command': 'cppunittest',
+        'kwargs': {'test_file': None},
+    },
+    'crashtest': {
+        'aliases': ('C', 'Rc', 'RC', 'rc'),
+        'mach_command': 'crashtest',
+        'kwargs': {'test_file': None},
+    },
+    'firefox-ui-functional': {
+        'aliases': ('Fxfn',),
+        'mach_command': 'firefox-ui-functional',
+        'kwargs': {},
+    },
+    'firefox-ui-update': {
+        'aliases': ('Fxup',),
+        'mach_command': 'firefox-ui-update',
+        'kwargs': {},
+    },
+    'jetpack': {
+        'aliases': ('J',),
+        'mach_command': 'jetpack-test',
+        'kwargs': {},
+    },
+    'check-spidermonkey': {
+        'aliases': ('Sm', 'sm'),
+        'mach_command': 'check-spidermonkey',
+        'kwargs': {'valgrind': False},
+    },
+    'mochitest-a11y': {
+        'mach_command': 'mochitest',
+        'kwargs': {'flavor': 'a11y', 'test_paths': None},
+    },
+    'mochitest-browser': {
+        'aliases': ('bc', 'BC', 'Bc'),
+        'mach_command': 'mochitest',
+        'kwargs': {'flavor': 'browser-chrome', 'test_paths': None},
+    },
+    'mochitest-chrome': {
+        'mach_command': 'mochitest',
+        'kwargs': {'flavor': 'chrome', 'test_paths': None},
+    },
+    'mochitest-devtools': {
+        'aliases': ('dt', 'DT', 'Dt'),
+        'mach_command': 'mochitest',
+        'kwargs': {'subsuite': 'devtools', 'test_paths': None},
+    },
+    'mochitest-plain': {
+        'mach_command': 'mochitest',
+        'kwargs': {'flavor': 'plain', 'test_paths': None},
+    },
+    'python': {
+        'mach_command': 'python-test',
+        'kwargs': {'tests': None},
+    },
+    'reftest': {
+        'aliases': ('RR', 'rr', 'Rr'),
+        'mach_command': 'reftest',
+        'kwargs': {'tests': None},
+    },
+    'web-platform-tests': {
+        'aliases': ('wpt',),
+        'mach_command': 'web-platform-tests',
+        'kwargs': {}
+    },
+    'valgrind': {
+        'aliases': ('V', 'v'),
+        'mach_command': 'valgrind-test',
+        'kwargs': {},
+    },
+    'xpcshell': {
+        'aliases': ('X', 'x'),
+        'mach_command': 'xpcshell-test',
+        'kwargs': {'test_file': 'all'},
+    },
+}
+
+# Maps test flavors to metadata on how to run that test.
+TEST_FLAVORS = {
+    'a11y': {
+        'mach_command': 'mochitest',
+        'kwargs': {'flavor': 'a11y', 'test_paths': []},
+    },
+    'browser-chrome': {
+        'mach_command': 'mochitest',
+        'kwargs': {'flavor': 'browser-chrome', 'test_paths': []},
+    },
+    'crashtest': {},
+    'chrome': {
+        'mach_command': 'mochitest',
+        'kwargs': {'flavor': 'chrome', 'test_paths': []},
+    },
+    'firefox-ui-functional': {
+        'mach_command': 'firefox-ui-functional',
+        'kwargs': {'tests': []},
+    },
+    'firefox-ui-update': {
+        'mach_command': 'firefox-ui-update',
+        'kwargs': {'tests': []},
+    },
+    'marionette': {
+        'mach_command': 'marionette-test',
+        'kwargs': {'tests': []},
+    },
+    'mochitest': {
+        'mach_command': 'mochitest',
+        'kwargs': {'flavor': 'mochitest', 'test_paths': []},
+    },
+    'python': {
+        'mach_command': 'python-test',
+        'kwargs': {},
+    },
+    'reftest': {
+        'mach_command': 'reftest',
+        'kwargs': {'tests': []}
+    },
+    'steeplechase': {},
+    'web-platform-tests': {
+        'mach_command': 'web-platform-tests',
+        'kwargs': {'include': []}
+    },
+    'xpcshell': {
+        'mach_command': 'xpcshell-test',
+        'kwargs': {'test_paths': []},
+    },
+}
+
+for i in range(1, MOCHITEST_TOTAL_CHUNKS + 1):
+    TEST_SUITES['mochitest-%d' %i] = {
+        'aliases': ('M%d' % i, 'm%d' % i),
+        'mach_command': 'mochitest',
+        'kwargs': {
+            'flavor': 'mochitest',
+            'subsuite': 'default',
+            'chunk_by_dir': MOCHITEST_CHUNK_BY_DIR,
+            'total_chunks': MOCHITEST_TOTAL_CHUNKS,
+            'this_chunk': i,
+            'test_paths': None,
+        },
+    }
+
+TEST_HELP = '''
+Test or tests to run. Tests can be specified by filename, directory, suite
+name or suite alias.
+
+The following test suites and aliases are supported: %s
+''' % ', '.join(sorted(TEST_SUITES))
+TEST_HELP = TEST_HELP.strip()
+
+
+@CommandProvider
+class Test(MachCommandBase):
+    @Command('test', category='testing', description='Run tests (detects the kind of test and runs it).')
+    @CommandArgument('what', default=None, nargs='*', help=TEST_HELP)
+    def test(self, what):
+        """Run tests from names or paths.
+
+        mach test accepts arguments specifying which tests to run. Each argument
+        can be:
+
+        * The path to a test file
+        * A directory containing tests
+        * A test suite name
+        * An alias to a test suite name (codes used on TreeHerder)
+
+        If no input is provided, tests will be run based on files changed in
+        the local tree. Relevant tests, tags, or flavors are determined by
+        IMPACTED_TESTS annotations in moz.build files relevant to the
+        changed files.
+
+        When paths or directories are given, they are first resolved to test
+        files known to the build system.
+
+        If resolved tests belong to more than one test type/flavor/harness,
+        the harness for each relevant type/flavor will be invoked. e.g. if
+        you specify a directory with xpcshell and browser chrome mochitests,
+        both harnesses will be invoked.
+        """
+        from mozbuild.testing import TestResolver
+
+        # Parse arguments and assemble a test "plan."
+        run_suites = set()
+        run_tests = []
+        resolver = self._spawn(TestResolver)
+
+        for entry in what:
+            # If the path matches the name or alias of an entire suite, run
+            # the entire suite.
+            if entry in TEST_SUITES:
+                run_suites.add(entry)
+                continue
+            suitefound = False
+            for suite, v in TEST_SUITES.items():
+                if entry in v.get('aliases', []):
+                    run_suites.add(suite)
+                    suitefound = True
+            if suitefound:
+                continue
+
+            # Now look for file/directory matches in the TestResolver.
+            relpath = self._wrap_path_argument(entry).relpath()
+            tests = list(resolver.resolve_tests(paths=[relpath]))
+            run_tests.extend(tests)
+
+            if not tests:
+                print('UNKNOWN TEST: %s' % entry, file=sys.stderr)
+
+        if not what:
+            # TODO: This isn't really related to try, and should be
+            # extracted to a common library for vcs interactions when it is
+            # introduced in bug 1185599.
+            from autotry import AutoTry
+            at = AutoTry(self.topsrcdir, resolver, self._mach_context)
+            changed_files = at.find_changed_files()
+            if changed_files:
+                print("Tests will be run based on modifications to the "
+                      "following files:\n\t%s" % "\n\t".join(changed_files))
+
+            from mozbuild.frontend.reader import (
+                BuildReader,
+                EmptyConfig,
+            )
+            config = EmptyConfig(self.topsrcdir)
+            reader = BuildReader(config)
+            files_info = reader.files_info(changed_files)
+
+            paths, tags, flavors = set(), set(), set()
+            for info in files_info.values():
+                paths |= info.test_files
+                tags |= info.test_tags
+                flavors |= info.test_flavors
+
+            # This requires multiple calls to resolve_tests, because the test
+            # resolver returns tests that match every condition, while we want
+            # tests that match any condition. Bug 1210213 tracks implementing
+            # more flexible querying.
+            if tags:
+                run_tests = list(resolver.resolve_tests(tags=tags))
+            if paths:
+                run_tests += [t for t in resolver.resolve_tests(paths=paths)
+                              if not (tags & set(t.get('tags', '').split()))]
+            if flavors:
+                run_tests = [t for t in run_tests if t['flavor'] not in flavors]
+                for flavor in flavors:
+                    run_tests += list(resolver.resolve_tests(flavor=flavor))
+
+        if not run_suites and not run_tests:
+            print(UNKNOWN_TEST)
+            return 1
+
+        status = None
+        for suite_name in run_suites:
+            suite = TEST_SUITES[suite_name]
+
+            if 'mach_command' in suite:
+                res = self._mach_context.commands.dispatch(
+                    suite['mach_command'], self._mach_context,
+                    **suite['kwargs'])
+                if res:
+                    status = res
+
+        buckets = {}
+        for test in run_tests:
+            key = (test['flavor'], test.get('subsuite', ''))
+            buckets.setdefault(key, []).append(test)
+
+        for (flavor, subsuite), tests in sorted(buckets.items()):
+            if flavor not in TEST_FLAVORS:
+                print(UNKNOWN_FLAVOR % flavor)
+                status = 1
+                continue
+
+            m = TEST_FLAVORS[flavor]
+            if 'mach_command' not in m:
+                print(UNKNOWN_FLAVOR % flavor)
+                status = 1
+                continue
+
+            kwargs = dict(m['kwargs'])
+            kwargs['subsuite'] = subsuite
+
+            res = self._mach_context.commands.dispatch(
+                    m['mach_command'], self._mach_context,
+                    test_objects=tests, **kwargs)
+            if res:
+                status = res
+
+        return status
+
+
+@CommandProvider
+class MachCommands(MachCommandBase):
+    @Command('cppunittest', category='testing',
+        description='Run cpp unit tests (C++ tests).')
+    @CommandArgument('test_files', nargs='*', metavar='N',
+        help='Test to run. Can be specified as one or more files or ' \
+            'directories, or omitted. If omitted, the entire test suite is ' \
+            'executed.')
+
+    def run_cppunit_test(self, **params):
+        import mozinfo
+        from mozlog import commandline
+        log = commandline.setup_logging("cppunittest",
+                                        {},
+                                        {"tbpl": sys.stdout})
+
+        # See if we have crash symbols
+        symbols_path = os.path.join(self.distdir, 'crashreporter-symbols')
+        if not os.path.isdir(symbols_path):
+            symbols_path = None
+
+        # If no tests specified, run all tests in main manifest
+        tests = params['test_files']
+        if len(tests) == 0:
+            tests = [os.path.join(self.distdir, 'cppunittests')]
+            manifest_path = os.path.join(self.topsrcdir, 'testing', 'cppunittest.ini')
+        else:
+            manifest_path = None
+
+        if conditions.is_android(self):
+            from mozrunner.devices.android_device import verify_android_device
+            verify_android_device(self, install=False)
+            return self.run_android_test(tests, symbols_path, manifest_path, log)
+
+        return self.run_desktop_test(tests, symbols_path, manifest_path, log)
+
+    def run_desktop_test(self, tests, symbols_path, manifest_path, log):
+        import runcppunittests as cppunittests
+        from mozlog import commandline
+
+        parser = cppunittests.CPPUnittestOptions()
+        commandline.add_logging_group(parser)
+        options, args = parser.parse_args()
+
+        options.symbols_path = symbols_path
+        options.manifest_path = manifest_path
+        options.xre_path = self.bindir
+
+        try:
+            result = cppunittests.run_test_harness(options, tests)
+        except Exception as e:
+            log.error("Caught exception running cpp unit tests: %s" % str(e))
+            result = False
+            raise
+
+        return 0 if result else 1
+
+    def run_android_test(self, tests, symbols_path, manifest_path, log):
+        import remotecppunittests as remotecppunittests
+        from mozlog import commandline
+
+        parser = remotecppunittests.RemoteCPPUnittestOptions()
+        commandline.add_logging_group(parser)
+        options, args = parser.parse_args()
+
+        options.symbols_path = symbols_path
+        options.manifest_path = manifest_path
+        options.xre_path = self.bindir
+        options.dm_trans = "adb"
+        options.local_lib = self.bindir.replace('bin', 'fennec')
+        for file in os.listdir(os.path.join(self.topobjdir, "dist")):
+            if file.endswith(".apk") and file.startswith("fennec"):
+                options.local_apk = os.path.join(self.topobjdir, "dist", file)
+                log.info("using APK: " + options.local_apk)
+                break
+
+        try:
+            result = remotecppunittests.run_test_harness(options, tests)
+        except Exception as e:
+            log.error("Caught exception running cpp unit tests: %s" % str(e))
+            result = False
+            raise
+
+        return 0 if result else 1
+
+def executable_name(name):
+    return name + '.exe' if sys.platform.startswith('win') else name
+
+@CommandProvider
+class CheckSpiderMonkeyCommand(MachCommandBase):
+    @Command('check-spidermonkey', category='testing', description='Run SpiderMonkey tests (JavaScript engine).')
+    @CommandArgument('--valgrind', action='store_true', help='Run jit-test suite with valgrind flag')
+
+    def run_checkspidermonkey(self, **params):
+        import subprocess
+        import sys
+
+        js = os.path.join(self.bindir, executable_name('js'))
+
+        print('Running jit-tests')
+        jittest_cmd = [os.path.join(self.topsrcdir, 'js', 'src', 'jit-test', 'jit_test.py'),
+              js, '--no-slow', '--jitflags=all']
+        if params['valgrind']:
+            jittest_cmd.append('--valgrind')
+
+        jittest_result = subprocess.call(jittest_cmd)
+
+        print('running jstests')
+        jstest_cmd = [os.path.join(self.topsrcdir, 'js', 'src', 'tests', 'jstests.py'),
+              js, '--jitflags=all']
+        jstest_result = subprocess.call(jstest_cmd)
+
+        print('running jsapi-tests')
+        jsapi_tests_cmd = [os.path.join(self.bindir, executable_name('jsapi-tests'))]
+        jsapi_tests_result = subprocess.call(jsapi_tests_cmd)
+
+        print('running check-style')
+        check_style_cmd = [sys.executable, os.path.join(self.topsrcdir, 'config', 'check_spidermonkey_style.py')]
+        check_style_result = subprocess.call(check_style_cmd, cwd=os.path.join(self.topsrcdir, 'js', 'src'))
+
+        print('running check-masm')
+        check_masm_cmd = [sys.executable, os.path.join(self.topsrcdir, 'config', 'check_macroassembler_style.py')]
+        check_masm_result = subprocess.call(check_masm_cmd, cwd=os.path.join(self.topsrcdir, 'js', 'src'))
+
+        print('running check-js-msg-encoding')
+        check_js_msg_cmd = [sys.executable, os.path.join(self.topsrcdir, 'config', 'check_js_msg_encoding.py')]
+        check_js_msg_result = subprocess.call(check_js_msg_cmd, cwd=self.topsrcdir)
+
+        all_passed = jittest_result and jstest_result and jsapi_tests_result and check_style_result and check_masm_result and check_js_msg_result
+
+        return all_passed
+
+@CommandProvider
+class JsapiTestsCommand(MachCommandBase):
+    @Command('jsapi-tests', category='testing', description='Run jsapi tests (JavaScript engine).')
+    @CommandArgument('test_name', nargs='?', metavar='N',
+        help='Test to run. Can be a prefix or omitted. If omitted, the entire ' \
+             'test suite is executed.')
+
+    def run_jsapitests(self, **params):
+        import subprocess
+
+        bin_suffix = ''
+        if sys.platform.startswith('win'):
+            bin_suffix = '.exe'
+
+        print('running jsapi-tests')
+        jsapi_tests_cmd = [os.path.join(self.bindir, executable_name('jsapi-tests'))]
+        if params['test_name']:
+            jsapi_tests_cmd.append(params['test_name'])
+
+        jsapi_tests_result = subprocess.call(jsapi_tests_cmd)
+
+        return jsapi_tests_result
+
+def autotry_parser():
+    from autotry import arg_parser
+    return arg_parser()
+
+@CommandProvider
+class PushToTry(MachCommandBase):
+    def normalise_list(self, items, allow_subitems=False):
+        from autotry import parse_arg
+
+        rv = defaultdict(list)
+        for item in items:
+            parsed = parse_arg(item)
+            for key, values in parsed.iteritems():
+                rv[key].extend(values)
+
+        if not allow_subitems:
+            if not all(item == [] for item in rv.itervalues()):
+                raise ValueError("Unexpected subitems in argument")
+            return rv.keys()
+        else:
+            return rv
+
+    def validate_args(self, **kwargs):
+        from autotry import AutoTry
+        if not kwargs["paths"] and not kwargs["tests"] and not kwargs["tags"]:
+            print("Paths, tags, or tests must be specified as an argument to autotry.")
+            sys.exit(1)
+
+        if kwargs["platforms"] is None:
+            if 'AUTOTRY_PLATFORM_HINT' in os.environ:
+                kwargs["platforms"] = [os.environ['AUTOTRY_PLATFORM_HINT']]
+            else:
+                print("Platforms must be specified as an argument to autotry.")
+                sys.exit(1)
+
+        try:
+            platforms = self.normalise_list(kwargs["platforms"])
+        except ValueError as e:
+            print("Error parsing -p argument:\n%s" % e.message)
+            sys.exit(1)
+
+        try:
+            tests = (self.normalise_list(kwargs["tests"], allow_subitems=True)
+                     if kwargs["tests"] else {})
+        except ValueError as e:
+            print("Error parsing -u argument (%s):\n%s" % (kwargs["tests"], e.message))
+            sys.exit(1)
+
+        try:
+            talos = (self.normalise_list(kwargs["talos"], allow_subitems=True)
+                     if kwargs["talos"] else [])
+        except ValueError as e:
+            print("Error parsing -t argument:\n%s" % e.message)
+            sys.exit(1)
+
+        paths = []
+        for p in kwargs["paths"]:
+            p = mozpath.normpath(os.path.abspath(p))
+            if not (os.path.isdir(p) and p.startswith(self.topsrcdir)):
+                print('Specified path "%s" is not a directory under the srcdir,'
+                      ' unable to specify tests outside of the srcdir' % p)
+                sys.exit(1)
+            if len(p) <= len(self.topsrcdir):
+                print('Specified path "%s" is at the top of the srcdir and would'
+                      ' select all tests.' % p)
+                sys.exit(1)
+            paths.append(os.path.relpath(p, self.topsrcdir))
+
+        try:
+            tags = self.normalise_list(kwargs["tags"]) if kwargs["tags"] else []
+        except ValueError as e:
+            print("Error parsing --tags argument:\n%s" % e.message)
+            sys.exit(1)
+
+        extra_values = {k['dest'] for k in AutoTry.pass_through_arguments.values()}
+        extra_args = {k: v for k, v in kwargs.items()
+                      if k in extra_values and v}
+
+        return kwargs["builds"], platforms, tests, talos, paths, tags, extra_args
+
+
+    @Command('try',
+             category='testing',
+             description='Push selected tests to the try server',
+             parser=autotry_parser)
+
+    def autotry(self, **kwargs):
+        """Autotry is in beta, please file bugs blocking 1149670.
+
+        Push the current tree to try, with the specified syntax.
+
+        Build options, platforms and regression tests may be selected
+        using the usual try options (-b, -p and -u respectively). In
+        addition, tests in a given directory may be automatically
+        selected by passing that directory as a positional argument to the
+        command. For example:
+
+        mach try -b d -p linux64 dom testing/web-platform/tests/dom
+
+        would schedule a try run for linux64 debug consisting of all
+        tests under dom/ and testing/web-platform/tests/dom.
+
+        Test selection using positional arguments is available for
+        mochitests, reftests, xpcshell tests and web-platform-tests.
+
+        Tests may be also filtered by passing --tag to the command,
+        which will run only tests marked as having the specified
+        tags e.g.
+
+        mach try -b d -p win64 --tag media
+
+        would run all tests tagged 'media' on Windows 64.
+
+        If both positional arguments or tags and -u are supplied, the
+        suites in -u will be run in full. Where tests are selected by
+        positional argument they will be run in a single chunk.
+
+        If no build option is selected, both debug and opt will be
+        scheduled. If no platform is selected a default is taken from
+        the AUTOTRY_PLATFORM_HINT environment variable, if set.
+
+        The command requires either its own mercurial extension ("push-to-try",
+        installable from mach mercurial-setup) or a git repo using git-cinnabar
+        (available at https://github.com/glandium/git-cinnabar).
+
+        """
+
+        from mozbuild.testing import TestResolver
+        from autotry import AutoTry
+
+        print("mach try is under development, please file bugs blocking 1149670.")
+
+        resolver_func = lambda: self._spawn(TestResolver)
+        at = AutoTry(self.topsrcdir, resolver_func, self._mach_context)
+
+        if kwargs["list"]:
+            at.list_presets()
+            sys.exit()
+
+        if kwargs["load"] is not None:
+            defaults = at.load_config(kwargs["load"])
+
+            if defaults is None:
+                print("No saved configuration called %s found in autotry.ini" % kwargs["load"],
+                      file=sys.stderr)
+
+            for key, value in kwargs.iteritems():
+                if value in (None, []) and key in defaults:
+                    kwargs[key] = defaults[key]
+
+        if kwargs["push"] and at.find_uncommited_changes():
+            print('ERROR please commit changes before continuing')
+            sys.exit(1)
+
+        if not any(kwargs[item] for item in ("paths", "tests", "tags")):
+            kwargs["paths"], kwargs["tags"] = at.find_paths_and_tags(kwargs["verbose"])
+
+        builds, platforms, tests, talos, paths, tags, extra = self.validate_args(**kwargs)
+
+        if paths or tags:
+            paths = [os.path.relpath(os.path.normpath(os.path.abspath(item)), self.topsrcdir)
+                     for item in paths]
+            paths_by_flavor = at.paths_by_flavor(paths=paths, tags=tags)
+
+            if not paths_by_flavor and not tests:
+                print("No tests were found when attempting to resolve paths:\n\n\t%s" %
+                      paths)
+                sys.exit(1)
+
+            if not kwargs["intersection"]:
+                paths_by_flavor = at.remove_duplicates(paths_by_flavor, tests)
+        else:
+            paths_by_flavor = {}
+
+        try:
+            msg = at.calc_try_syntax(platforms, tests, talos, builds, paths_by_flavor, tags,
+                                     extra, kwargs["intersection"])
+        except ValueError as e:
+            print(e.message)
+            sys.exit(1)
+
+        if kwargs["verbose"] and paths_by_flavor:
+            print('The following tests will be selected: ')
+            for flavor, paths in paths_by_flavor.iteritems():
+                print("%s: %s" % (flavor, ",".join(paths)))
+
+        if kwargs["verbose"] or not kwargs["push"]:
+            print('The following try syntax was calculated:\n%s' % msg)
+
+        if kwargs["push"]:
+            at.push_to_try(msg, kwargs["verbose"])
+
+        if kwargs["save"] is not None:
+            at.save_config(kwargs["save"], msg)
+
+
+def get_parser(argv=None):
+    parser = ArgumentParser()
+    parser.add_argument(dest="suite_name",
+                        nargs=1,
+                        choices=['mochitest'],
+                        type=str,
+                        help="The test for which chunk should be found. It corresponds "
+                             "to the mach test invoked (only 'mochitest' currently).")
+
+    parser.add_argument(dest="test_path",
+                        nargs=1,
+                        type=str,
+                        help="The test (any mochitest) for which chunk should be found.")
+
+    parser.add_argument('--total-chunks',
+                        type=int,
+                        dest='total_chunks',
+                        required=True,
+                        help='Total number of chunks to split tests into.',
+                        default=None)
+
+    parser.add_argument('--chunk-by-runtime',
+                        action='store_true',
+                        dest='chunk_by_runtime',
+                        help='Group tests such that each chunk has roughly the same runtime.',
+                        default=False)
+
+    parser.add_argument('--chunk-by-dir',
+                        type=int,
+                        dest='chunk_by_dir',
+                        help='Group tests together in the same chunk that are in the same top '
+                             'chunkByDir directories.',
+                        default=None)
+
+    parser.add_argument('--disable-e10s',
+                        action='store_false',
+                        dest='e10s',
+                        help='Find test on chunk with electrolysis preferences disabled.',
+                        default=True)
+
+    parser.add_argument('-p', '--platform',
+                        choices=['linux', 'linux64', 'mac', 'macosx64', 'win32', 'win64'],
+                        dest='platform',
+                        help="Platform for the chunk to find the test.",
+                        default=None)
+
+    parser.add_argument('--debug',
+                        action='store_true',
+                        dest='debug',
+                        help="Find the test on chunk in a debug build.",
+                        default=False)
+
+    return parser
+
+
+def download_mozinfo(platform=None, debug_build=False):
+    temp_dir = tempfile.mkdtemp()
+    temp_path = os.path.join(temp_dir, "mozinfo.json")
+    args = [
+        'mozdownload',
+        '-t', 'tinderbox',
+        '--ext', 'mozinfo.json',
+        '-d', temp_path,
+    ]
+    if platform:
+        if platform == 'macosx64':
+            platform = 'mac64'
+        args.extend(['-p', platform])
+    if debug_build:
+        args.extend(['--debug-build'])
+
+    subprocess.call(args)
+    return temp_dir, temp_path
+
+@CommandProvider
+class ChunkFinder(MachCommandBase):
+    @Command('find-test-chunk', category='testing',
+             description='Find which chunk a test belongs to (works for mochitest).',
+             parser=get_parser)
+    def chunk_finder(self, **kwargs):
+        total_chunks = kwargs['total_chunks']
+        test_path = kwargs['test_path'][0]
+        suite_name = kwargs['suite_name'][0]
+        _, dump_tests = tempfile.mkstemp()
+
+        from mozbuild.testing import TestResolver
+        resolver = self._spawn(TestResolver)
+        relpath = self._wrap_path_argument(test_path).relpath()
+        tests = list(resolver.resolve_tests(paths=[relpath]))
+        if len(tests) != 1:
+            print('No test found for test_path: %s' % test_path)
+            sys.exit(1)
+
+        flavor = tests[0]['flavor']
+        subsuite = tests[0]['subsuite']
+        args = {
+            'totalChunks': total_chunks,
+            'dump_tests': dump_tests,
+            'chunkByDir': kwargs['chunk_by_dir'],
+            'chunkByRuntime': kwargs['chunk_by_runtime'],
+            'e10s': kwargs['e10s'],
+            'subsuite': subsuite,
+        }
+
+        temp_dir = None
+        if kwargs['platform'] or kwargs['debug']:
+            self._activate_virtualenv()
+            self.virtualenv_manager.install_pip_package('mozdownload==1.17')
+            temp_dir, temp_path = download_mozinfo(kwargs['platform'], kwargs['debug'])
+            args['extra_mozinfo_json'] = temp_path
+
+        found = False
+        for this_chunk in range(1, total_chunks+1):
+            args['thisChunk'] = this_chunk
+            try:
+                self._mach_context.commands.dispatch(suite_name, self._mach_context, flavor=flavor, resolve_tests=False, **args)
+            except SystemExit:
+                pass
+            except KeyboardInterrupt:
+                break
+
+            fp = open(os.path.expanduser(args['dump_tests']), 'r')
+            tests = json.loads(fp.read())['active_tests']
+            for test in tests:
+                if test_path == test['path']:
+                    if 'disabled' in test:
+                        print('The test %s for flavor %s is disabled on the given platform' % (test_path, flavor))
+                    else:
+                        print('The test %s for flavor %s is present in chunk number: %d' % (test_path, flavor, this_chunk))
+                    found = True
+                    break
+
+            if found:
+                break
+
+        if not found:
+            raise Exception("Test %s not found." % test_path)
+        # Clean up the file
+        os.remove(dump_tests)
+        if temp_dir:
+            shutil.rmtree(temp_dir)