implemented a basic double quote string fixer
diff --git a/tests/string_fixer_test.py b/tests/string_fixer_test.py
new file mode 100644
index 0000000..15b9f19
--- /dev/null
+++ b/tests/string_fixer_test.py
@@ -0,0 +1,80 @@
+from __future__ import absolute_import
+from __future__ import print_function
+from __future__ import unicode_literals
+
+import pytest
+
+from pre_commit_hooks.string_fixer import main
+
+TESTS = (
+ # Base cases
+ (
+ "''",
+ "''",
+ 0
+ ),
+ (
+ '""',
+ "''",
+ 1
+ ),
+ (
+ r'"\'"',
+ r'"\'"',
+ 0
+ ),
+ (
+ r'"\""',
+ r'"\""',
+ 0
+ ),
+ (
+ r"'\"\"'",
+ r"'\"\"'",
+ 0
+ ),
+ # String somewhere in the line
+ (
+ 'x = "foo"',
+ "x = 'foo'",
+ 1
+ ),
+ # Test escaped characters
+ (
+ r'"\'"',
+ r'"\'"',
+ 0
+ ),
+ # Docstring
+ (
+ '""" Foo """',
+ '""" Foo """',
+ 0
+ ),
+ # Fuck it, won't even try to fix
+ (
+ """
+ x = " \\n
+ foo \\n
+ "\n
+ """,
+ """
+ x = " \\n
+ foo \\n
+ "\n
+ """,
+ 0
+ ),
+)
+
+
+@pytest.mark.parametrize(('input_s', 'expected_output', 'expected_retval'), TESTS)
+def test_rewrite(input_s, expected_output, expected_retval, tmpdir):
+ tmpfile = tmpdir.join('file.txt')
+
+ with open(tmpfile.strpath, 'w') as f:
+ f.write(input_s)
+
+ retval = main([tmpfile.strpath])
+ assert tmpfile.read() == expected_output
+ assert retval == expected_retval
