gecko-dev/config/tests/unit-mozunit.py

# 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/.

import sys
import os
from mozunit import main, MockedOpen
import unittest
from tempfile import mkstemp

class TestMozUnit(unittest.TestCase):
    def test_mocked_open(self):
        # Create a temporary file on the file system.
        (fd, path) = mkstemp()
        with os.fdopen(fd, 'w') as file:
            file.write('foobar');

        self.assertFalse(os.path.exists('file1'))
        self.assertFalse(os.path.exists('file2'))

        with MockedOpen({'file1': 'content1',
                         'file2': 'content2'}):
            self.assertTrue(os.path.exists('file1'))
            self.assertTrue(os.path.exists('file2'))
            self.assertFalse(os.path.exists('foo/file1'))

            # Check the contents of the files given at MockedOpen creation.
            self.assertEqual(open('file1', 'r').read(), 'content1')
            self.assertEqual(open('file2', 'r').read(), 'content2')

            # Check that overwriting these files alters their content.
            with open('file1', 'w') as file:
                file.write('foo')
            self.assertTrue(os.path.exists('file1'))
            self.assertEqual(open('file1', 'r').read(), 'foo')

            # ... but not until the file is closed.
            file = open('file2', 'w')
            file.write('bar')
            self.assertEqual(open('file2', 'r').read(), 'content2')
            file.close()
            self.assertEqual(open('file2', 'r').read(), 'bar')

            # Check that appending to a file does append
            with open('file1', 'a') as file:
                file.write('bar')
            self.assertEqual(open('file1', 'r').read(), 'foobar')

            self.assertFalse(os.path.exists('file3'))

            # Opening a non-existing file ought to fail.
            self.assertRaises(IOError, open, 'file3', 'r')
            self.assertFalse(os.path.exists('file3'))

            # Check that writing a new file does create the file.
            with open('file3', 'w') as file:
                file.write('baz')
            self.assertEqual(open('file3', 'r').read(), 'baz')
            self.assertTrue(os.path.exists('file3'))

            # Check the content of the file created outside MockedOpen.
            self.assertEqual(open(path, 'r').read(), 'foobar')

            # Check that overwriting a file existing on the file system
            # does modify its content.
            with open(path, 'w') as file:
                file.write('bazqux')
            self.assertEqual(open(path, 'r').read(), 'bazqux')

        with MockedOpen():
            # Check that appending to a file existing on the file system
            # does modify its content.
            with open(path, 'a') as file:
                file.write('bazqux')
            self.assertEqual(open(path, 'r').read(), 'foobarbazqux')

        # Check that the file was not actually modified on the file system.
        self.assertEqual(open(path, 'r').read(), 'foobar')
        os.remove(path)

        # Check that the file created inside MockedOpen wasn't actually
        # created.
        self.assertRaises(IOError, open, 'file3', 'r')

if __name__ == "__main__":
    main()