import unittest

from django.conf import settings

from django.db.models import get_app, get_apps

from django.test import _doctest as doctest

from django.test.utils import setup_test_environment, teardown_test_environment

from django.test.utils import create_test_db, destroy_test_db

from django.test.testcases import OutputChecker, DocTestRunner

# The module name for tests outside models.py

TEST_MODULE = 'tests'

doctestOutputChecker = OutputChecker()

def get_tests(app_module):

    try:

        app_path = app_module.__name__.split('.')[:-1]

        test_module = __import__('.'.join(app_path + [TEST_MODULE]), {}, {}, TEST_MODULE)

    except ImportError, e:

        # Couldn't import tests.py. Was it due to a missing file, or

        # due to an import error in a tests.py that actually exists?

        import os.path

        from imp import find_module

        try:

            mod = find_module(TEST_MODULE, [os.path.dirname(app_module.__file__)])

        except ImportError:

            # 'tests' module doesn't exist. Move on.

            test_module = None

        else:

            # The module exists, so there must be an import error in the 

            # test module itself. We don't need the module; so if the

            # module was a single file module (i.e., tests.py), close the file

            # handle returned by find_module. Otherwise, the test module

            # is a directory, and there is nothing to close.

            if mod[0]:

                mod[0].close()

            raise

    return test_module

def build_suite(app_module):

    "Create a complete Django test suite for the provided application module"

    suite = unittest.TestSuite()

    # Load unit and doctests in the models.py module. If module has

    # a suite() method, use it. Otherwise build the test suite ourselves.

    if hasattr(app_module, 'suite'):

        suite.addTest(app_module.suite())

    else:

        suite.addTest(unittest.defaultTestLoader.loadTestsFromModule(app_module))

        try:

            suite.addTest(doctest.DocTestSuite(app_module,

                                               checker=doctestOutputChecker,

                                               runner=DocTestRunner))

        except ValueError:

            # No doc tests in models.py

            pass

    # Check to see if a separate 'tests' module exists parallel to the 

    # models module

    test_module = get_tests(app_module)

    if test_module:

        # Load unit and doctests in the tests.py module. If module has

        # a suite() method, use it. Otherwise build the test suite ourselves.

        if hasattr(test_module, 'suite'):

            suite.addTest(test_module.suite())

        else:

            suite.addTest(unittest.defaultTestLoader.loadTestsFromModule(test_module))

            try:            

                suite.addTest(doctest.DocTestSuite(test_module, 

                                                   checker=doctestOutputChecker,

                                                   runner=DocTestRunner))

            except ValueError:

                # No doc tests in tests.py

                pass

    return suite

def build_test(label):

    """Construct a test case a test with the specified label. Label should 

    be of the form model.TestClass or model.TestClass.test_method. Returns

    an instantiated test or test suite corresponding to the label provided.

    """

    parts = label.split('.')

    if len(parts) < 2 or len(parts) > 3:

        raise ValueError("Test label '%s' should be of the form app.TestCase or app.TestCase.test_method" % label)

    app_module = get_app(parts[0])

    TestClass = getattr(app_module, parts[1], None)

    # Couldn't find the test class in models.py; look in tests.py

    if TestClass is None:

        test_module = get_tests(app_module)

        if test_module:

            TestClass = getattr(test_module, parts[1], None)

    if len(parts) == 2: # label is app.TestClass

        try:

            return unittest.TestLoader().loadTestsFromTestCase(TestClass)

        except TypeError:

            raise ValueError("Test label '%s' does not refer to a test class" % label)            

    else: # label is app.TestClass.test_method

        return TestClass(parts[2])

def run_tests(test_labels, verbosity=1, interactive=True, extra_tests=[]):

    """

    Run the unit tests for all the test labels in the provided list.

    Labels must be of the form:

     - app.TestClass.test_method

        Run a single specific test method

     - app.TestClass

        Run all the test methods in a given class

     - app

        Search for doctests and unittests in the named application.

    When looking for tests, the test runner will look in the models and

    tests modules for the application.

    A list of 'extra' tests may also be provided; these tests

    will be added to the test suite.

    Returns the number of tests that failed.

    """

    setup_test_environment()

    settings.DEBUG = False    

    suite = unittest.TestSuite()

    if test_labels:

        for label in test_labels:

            if '.' in label:

                suite.addTest(build_test(label))

            else:

                app = get_app(label)

                suite.addTest(build_suite(app))

    else:

        for app in get_apps():

            suite.addTest(build_suite(app))

    for test in extra_tests:

        suite.addTest(test)

    old_name = settings.DATABASE_NAME

    create_test_db(verbosity, autoclobber=not interactive)

    result = unittest.TextTestRunner(verbosity=verbosity).run(suite)

    destroy_test_db(old_name, verbosity)

    teardown_test_environment()

    return len(result.failures) + len(result.errors)