def test_write_pot(self):
        s = ConfigSettings()
        s.register_provider(Provider1)
        s.register_provider(Provider2)

        # Just a basic sanity test.
        temp = NamedTemporaryFile('wt')
        s.write_pot(temp)
        temp.flush()

    def test_file_reading_single(self):
        temp = NamedTemporaryFile(mode='wt')
        temp.write(CONFIG1)
        temp.flush()

        s = ConfigSettings()
        s.register_provider(Provider1)

        s.load_file(temp.name)

        self.assertEqual(s.foo.bar, 'bar_value')

    def test_hash_file_known_hash(self):
        """Ensure a known hash value is recreated."""
        data = b'The quick brown fox jumps over the lazy cog'
        expected = 'de9f2c7fd25e1b3afad3e85a0bd17d9b100db4b3'

        temp = NamedTemporaryFile()
        temp.write(data)
        temp.flush()

        actual = hash_file(temp.name)

        self.assertEqual(actual, expected)

    def test_pruning(self):
        """Ensure old warnings are removed from database appropriately."""
        db = WarningsDatabase()

        source_files = []
        for i in range(1, 21):
            temp = NamedTemporaryFile(mode='wt')
            temp.write('x' * (100 * i))
            temp.flush()

            # Keep reference so it doesn't get GC'd and deleted.
            source_files.append(temp)

            w = CompilerWarning()
            w['filename'] = temp.name
            w['line'] = 1
            w['column'] = i * 10
            w['message'] = 'irrelevant'

            db.insert(w)

        self.assertEqual(len(db), 20)

        # If we change a source file, inserting a new warning should nuke the
        # old one.
        source_files[0].write('extra')
        source_files[0].flush()

        w = CompilerWarning()
        w['filename'] = source_files[0].name
        w['line'] = 1
        w['column'] = 50
        w['message'] = 'replaced'

        db.insert(w)

        self.assertEqual(len(db), 20)

        warnings = list(db.warnings_for_file(source_files[0].name))
        self.assertEqual(len(warnings), 1)
        self.assertEqual(warnings[0]['column'], w['column'])

        # If we delete the source file, calling prune should cause the warnings
        # to go away.
        old_filename = source_files[0].name
        del source_files[0]

        self.assertFalse(os.path.exists(old_filename))

        db.prune()
        self.assertEqual(len(db), 19)

    def test_hash_file_large(self):
        """Ensure that hash_file seems to work with a large file."""
        data = b'x' * 1048576

        hasher = hashlib.sha1()
        hasher.update(data)
        expected = hasher.hexdigest()

        temp = NamedTemporaryFile()
        temp.write(data)
        temp.flush()

        actual = hash_file(temp.name)

        self.assertEqual(actual, expected)

    def test_file_reading_multiple(self):
        """Loading multiple files has proper overwrite behavior."""
        temp1 = NamedTemporaryFile(mode='wt')
        temp1.write(CONFIG1)
        temp1.flush()

        temp2 = NamedTemporaryFile(mode='wt')
        temp2.write(CONFIG2)
        temp2.flush()

        s = ConfigSettings()
        s.register_provider(Provider1)

        s.load_files([temp1.name, temp2.name])

        self.assertEqual(s.foo.bar, 'value2')

    def test_file_writing(self):
        s = ConfigSettings()
        s.register_provider(Provider2)

        s.a.string = 'foo'
        s.a.boolean = False

        temp = NamedTemporaryFile('wt')
        s.write(temp)
        temp.flush()

        s2 = ConfigSettings()
        s2.register_provider(Provider2)

        s2.load_file(temp.name)

        self.assertEqual(s.a.string, s2.a.string)
        self.assertEqual(s.a.boolean, s2.a.boolean)

    def test_hashing(self):
        """Ensure that hashing files on insert works."""
        db = WarningsDatabase()

        temp = NamedTemporaryFile(mode='wt')
        temp.write('x' * 100)
        temp.flush()

        w = CompilerWarning()
        w['filename'] = temp.name
        w['line'] = 1
        w['column'] = 4
        w['message'] = 'foo bar'

        # Should not throw.
        db.insert(w)

        w['filename'] = 'DOES_NOT_EXIST'

        with self.assertRaises(Exception):
            db.insert(w)