# Cover: code coverage

Note

Newer versions of coverage contain their own nose plugin which is superior to the builtin plugin. It exposes more of coverage’s options and uses coverage’s native html output. Depending on the version of coverage installed, the included plugin may override the nose builtin plugin, or be available under a different name. Check `nosetests --help` or `nosetests --plugins` to find out which coverage plugin is available on your system.

If you have Ned Batchelder’s coverage module installed, you may activate a coverage report with the `--with-coverage` switch or NOSE_WITH_COVERAGE environment variable. The coverage report will cover any python source module imported after the start of the test run, excluding modules that match testMatch. If you want to include those modules too, use the `--cover-tests` switch, or set the NOSE_COVER_TESTS environment variable to a true value. To restrict the coverage report to modules from a particular package or packages, use the `--cover-package` switch or the NOSE_COVER_PACKAGE environment variable.

## Options

`--with-coverage```

  Enable plugin Coverage: Activate a coverage report using Ned Batchelder’s coverage module. [NOSE_WITH_COVERAGE]

`--cover-package``=PACKAGE`

  Restrict coverage output to selected packages [NOSE_COVER_PACKAGE]

`--cover-erase```

  Erase previously collected coverage statistics before run

`--cover-tests```

  Include test modules in coverage report [NOSE_COVER_TESTS]

`--cover-min-percentage``=DEFAULT`

  Minimum percentage of coverage for tests to pass [NOSE_COVER_MIN_PERCENTAGE]

`--cover-inclusive```

  Include all python files under working directory in coverage report. Useful for discovering holes in test coverage if not all files are imported by the test suite. [NOSE_COVER_INCLUSIVE]

`--cover-html```

  Produce HTML coverage information

`--cover-html-dir``=DIR`

  Produce HTML coverage information in dir

`--cover-branches```

  Include branch coverage in coverage report [NOSE_COVER_BRANCHES]

`--cover-xml```

  Produce XML coverage information

`--cover-xml-file``=FILE`

  Produce XML coverage information in file

## Plugin

class `nose.plugins.cover.``Coverage`

  Bases: `nose.plugins.base.Plugin`

  Activate a coverage report using Ned Batchelder’s coverage module.

  `afterTest`(*args, **kwargs)

    Stop recording coverage information.

  `beforeTest`(*args, **kwargs)

    Begin recording coverage information.

  `configure`(options, conf)

    Configure plugin.

  `options`(parser, env)

    Add options to command line.

  `report`(stream)

    Output code coverage report.

  `wantFile`(file, package=None)

    If inclusive coverage enabled, return true for all source files in wanted packages.

## Source

    """If you have Ned Batchelder's coverage_ module installed, you may activate a
    coverage report with the ``--with-coverage`` switch or NOSE_WITH_COVERAGE
    environment variable. The coverage report will cover any python source module
    imported after the start of the test run, excluding modules that match
    testMatch. If you want to include those modules too, use the ``--cover-tests``
    switch, or set the NOSE_COVER_TESTS environment variable to a true value. To
    restrict the coverage report to modules from a particular package or packages,
    use the ``--cover-package`` switch or the NOSE_COVER_PACKAGE environment
    variable.

    .. _coverage: http://www.nedbatchelder.com/code/modules/coverage.html
    """
    import logging
    import re
    import sys
    import StringIO
    from nose.plugins.base import Plugin
    from nose.util import src, tolist

    log = logging.getLogger(__name__)

    class Coverage(Plugin):
        """
        Activate a coverage report using Ned Batchelder's coverage module.
        """
        coverTests = False
        coverPackages = None
        coverInstance = None
        coverErase = False
        coverMinPercentage = None
        score = 200
        status = {}

        def options(self, parser, env):
            """
            Add options to command line.
            """
            super(Coverage, self).options(parser, env)
            parser.add_option("--cover-package", action="append",
                              default=env.get('NOSE_COVER_PACKAGE'),
                              metavar="PACKAGE",
                              dest="cover_packages",
                              help="Restrict coverage output to selected packages "
                              "[NOSE_COVER_PACKAGE]")
            parser.add_option("--cover-erase", action="store_true",
                              default=env.get('NOSE_COVER_ERASE'),
                              dest="cover_erase",
                              help="Erase previously collected coverage "
                              "statistics before run")
            parser.add_option("--cover-tests", action="store_true",
                              dest="cover_tests",
                              default=env.get('NOSE_COVER_TESTS'),
                              help="Include test modules in coverage report "
                              "[NOSE_COVER_TESTS]")
            parser.add_option("--cover-min-percentage", action="store",
                              dest="cover_min_percentage",
                              default=env.get('NOSE_COVER_MIN_PERCENTAGE'),
                              help="Minimum percentage of coverage for tests "
                              "to pass [NOSE_COVER_MIN_PERCENTAGE]")
            parser.add_option("--cover-inclusive", action="store_true",
                              dest="cover_inclusive",
                              default=env.get('NOSE_COVER_INCLUSIVE'),
                              help="Include all python files under working "
                              "directory in coverage report.  Useful for "
                              "discovering holes in test coverage if not all "
                              "files are imported by the test suite. "
                              "[NOSE_COVER_INCLUSIVE]")
            parser.add_option("--cover-html", action="store_true",
                              default=env.get('NOSE_COVER_HTML'),
                              dest='cover_html',
                              help="Produce HTML coverage information")
            parser.add_option('--cover-html-dir', action='store',
                              default=env.get('NOSE_COVER_HTML_DIR', 'cover'),
                              dest='cover_html_dir',
                              metavar='DIR',
                              help='Produce HTML coverage information in dir')
            parser.add_option("--cover-branches", action="store_true",
                              default=env.get('NOSE_COVER_BRANCHES'),
                              dest="cover_branches",
                              help="Include branch coverage in coverage report "
                              "[NOSE_COVER_BRANCHES]")
            parser.add_option("--cover-xml", action="store_true",
                              default=env.get('NOSE_COVER_XML'),
                              dest="cover_xml",
                              help="Produce XML coverage information")
            parser.add_option("--cover-xml-file", action="store",
                              default=env.get('NOSE_COVER_XML_FILE', 'coverage.xml'),
                              dest="cover_xml_file",
                              metavar="FILE",
                              help="Produce XML coverage information in file")

        def configure(self, options, conf):
            """
            Configure plugin.
            """
            try:
                self.status.pop('active')
            except KeyError:
                pass
            super(Coverage, self).configure(options, conf)
            if self.enabled:
                try:
                    import coverage
                    if not hasattr(coverage, 'coverage'):
                        raise ImportError("Unable to import coverage module")
                except ImportError:
                    log.error("Coverage not available: "
                              "unable to import coverage module")
                    self.enabled = False
                    return
            self.conf = conf
            self.coverErase = options.cover_erase
            self.coverTests = options.cover_tests
            self.coverPackages = []
            if options.cover_packages:
                if isinstance(options.cover_packages, (list, tuple)):
                    cover_packages = options.cover_packages
                else:
                    cover_packages = [options.cover_packages]
                for pkgs in [tolist(x) for x in cover_packages]:
                    self.coverPackages.extend(pkgs)
            self.coverInclusive = options.cover_inclusive
            if self.coverPackages:
                log.info("Coverage report will include only packages: %s",
                         self.coverPackages)
            self.coverHtmlDir = None
            if options.cover_html:
                self.coverHtmlDir = options.cover_html_dir
                log.debug('Will put HTML coverage report in %s', self.coverHtmlDir)
            self.coverBranches = options.cover_branches
            self.coverXmlFile = None
            if options.cover_min_percentage:
                self.coverMinPercentage = int(options.cover_min_percentage.rstrip('%'))
            if options.cover_xml:
                self.coverXmlFile = options.cover_xml_file
                log.debug('Will put XML coverage report in %s', self.coverXmlFile)
            if self.enabled:
                self.status['active'] = True
                self.coverInstance = coverage.coverage(auto_data=False,
                    branch=self.coverBranches, data_suffix=conf.worker,
                    source=self.coverPackages)
                self.coverInstance._warn_no_data = False
                self.coverInstance.is_worker = conf.worker
                self.coverInstance.exclude('#pragma[: ]+[nN][oO] [cC][oO][vV][eE][rR]')

                log.debug("Coverage begin")
                self.skipModules = sys.modules.keys()[:]
                if self.coverErase:
                    log.debug("Clearing previously collected coverage statistics")
                    self.coverInstance.combine()
                    self.coverInstance.erase()

                if not self.coverInstance.is_worker:
                    self.coverInstance.load()
                    self.coverInstance.start()

        def beforeTest(self, *args, **kwargs):
            """
            Begin recording coverage information.
            """

            if self.coverInstance.is_worker:
                self.coverInstance.load()
                self.coverInstance.start()

        def afterTest(self, *args, **kwargs):
            """
            Stop recording coverage information.
            """

            if self.coverInstance.is_worker:
                self.coverInstance.stop()
                self.coverInstance.save()

        def report(self, stream):
            """
            Output code coverage report.
            """
            log.debug("Coverage report")
            self.coverInstance.stop()
            self.coverInstance.combine()
            self.coverInstance.save()
            modules = [module
                        for name, module in sys.modules.items()
                        if self.wantModuleCoverage(name, module)]
            log.debug("Coverage report will cover modules: %s", modules)
            self.coverInstance.report(modules, file=stream)

            import coverage
            if self.coverHtmlDir:
                log.debug("Generating HTML coverage report")
                try:
                    self.coverInstance.html_report(modules, self.coverHtmlDir)
                except coverage.misc.CoverageException, e:
                    log.warning("Failed to generate HTML report: %s" % str(e))

            if self.coverXmlFile:
                log.debug("Generating XML coverage report")
                try:
                    self.coverInstance.xml_report(modules, self.coverXmlFile)
                except coverage.misc.CoverageException, e:
                    log.warning("Failed to generate XML report: %s" % str(e))

            # make sure we have minimum required coverage
            if self.coverMinPercentage:
                f = StringIO.StringIO()
                self.coverInstance.report(modules, file=f)

                multiPackageRe = (r'-------\s\w+\s+\d+\s+\d+(?:\s+\d+\s+\d+)?'
                                  r'\s+(\d+)%\s+\d*\s{0,1}$')
                singlePackageRe = (r'-------\s[\w./]+\s+\d+\s+\d+(?:\s+\d+\s+\d+)?'
                                   r'\s+(\d+)%(?:\s+[-\d, ]+)\s{0,1}$')

                m = re.search(multiPackageRe, f.getvalue())
                if m is None:
                    m = re.search(singlePackageRe, f.getvalue())

                if m:
                    percentage = int(m.groups()[0])
                    if percentage < self.coverMinPercentage:
                        log.error('TOTAL Coverage did not reach minimum '
                                  'required: %d%%' % self.coverMinPercentage)
                        sys.exit(1)
                else:
                    log.error("No total percentage was found in coverage output, "
                              "something went wrong.")

        def wantModuleCoverage(self, name, module):
            if not hasattr(module, '__file__'):
                log.debug("no coverage of %s: no __file__", name)
                return False
            module_file = src(module.__file__)
            if not module_file or not module_file.endswith('.py'):
                log.debug("no coverage of %s: not a python file", name)
                return False
            if self.coverPackages:
                for package in self.coverPackages:
                    if (re.findall(r'^%s\b' % re.escape(package), name)
                        and (self.coverTests
                             or not self.conf.testMatch.search(name))):
                        log.debug("coverage for %s", name)
                        return True
            if name in self.skipModules:
                log.debug("no coverage for %s: loaded before coverage start",
                          name)
                return False
            if self.conf.testMatch.search(name) and not self.coverTests:
                log.debug("no coverage for %s: is a test", name)
                return False
            # accept any package that passed the previous tests, unless
            # coverPackages is on -- in that case, if we wanted this
            # module, we would have already returned True
            return not self.coverPackages

        def wantFile(self, file, package=None):
            """If inclusive coverage enabled, return true for all source files
            in wanted packages.
            """
            if self.coverInclusive:
                if file.endswith(".py"):
                    if package and self.coverPackages:
                        for want in self.coverPackages:
                            if package.startswith(want):
                                return True
                    else:
                        return True
            return None