A Django command to generate a test coverage report

coverage.py

from __future__ import absolute_import
import os
import sys
import webbrowser

from django.conf import settings
from django.core.management import setup_environ
from django.core.management.commands import test
from django.utils.importlib import import_module
from django.db.models.loading import cache

class Command(test.Command):
    help = test.Command.help.rstrip('.') + ' and create a coverage report.'

    def handle(self, *test_labels, **options):
        import coverage
        cov = coverage.coverage(cover_pylib=False, branch=True)
        cov.use_cache(False)
        cov.start()
        base_mod = os.environ['DJANGO_SETTINGS_MODULE'].split('.', 1)[0]
        to_import = []
        for n, m in sys.modules.items():
            if base_mod in n and m is not None and hasattr(m, '__file__') and os.path.dirname(m.__file__) != os.path.dirname(__file__):
                del sys.modules[n]
                to_import.append(n)
        for app_label, model_dict in cache.app_models.items():
            for model_name, model in model_dict.items():
                if model.__module__ in to_import:
                    del model_dict[model_name]
        for n in to_import:
            sys.modules[n] = import_module(n)
        proj_dir = setup_environ(import_module(os.environ['DJANGO_SETTINGS_MODULE']))
        try:
            result = super(Command, self).handle(*test_labels, **options)
        finally:
            cov.stop()
        modules = [m for _, m in sys.modules.items()
                    if m is not None and hasattr(m, '__file__')
                    and os.path.splitext(m.__file__)[-1] in ('.py', '.pyc')
                    and m.__file__.startswith(proj_dir)
                    and m.__file__ != __file__]
        self._report(cov, modules)
        return result
    
    def _report(self, cov, modules):
        if hasattr(settings, 'TEST_COVERAGE_OUTPUT'):
            html_dir = os.path.join(os.path.dirname(settings.TEST_COVERAGE_OUTPUT), 'coverage_html')
        else:
            html_dir = os.path.join(proj_dir, 'build', 'coverage_html')
        if not os.path.exists(html_dir):
            os.makedirs(html_dir)
        cov.html_report(modules, html_dir)
        webbrowser.open_new_tab('file://'+html_dir+'/index.html')