1 files changed, 62 insertions, 0 deletions
diff --git a/tests/string_fixer_test.py b/tests/string_fixer_test.py
new file mode 100644
index 0000000..8eb164c
--- /dev/null
+++ b/tests/string_fixer_test.py
@@ -0,0 +1,62 @@
+from __future__ import annotations
+
+import textwrap
+
+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),
+    (
+        textwrap.dedent(
+            """
+        x = " \\
+        foo \\
+        "\n
+        """,
+        ),
+        textwrap.dedent(
+            """
+        x = ' \\
+        foo \\
+        '\n
+        """,
+        ),
+        1,
+    ),
+    ('"foo""bar"', "'foo''bar'", 1),
+    pytest.param(
+        "f'hello{\"world\"}'",
+        "f'hello{\"world\"}'",
+        0,
+        id='ignore nested fstrings',
+    ),
+)
+
+
+@pytest.mark.parametrize(('input_s', 'output', 'expected_retval'), TESTS)
+def test_rewrite(input_s, output, expected_retval, tmpdir):
+    path = tmpdir.join('file.py')
+    path.write(input_s)
+    retval = main([str(path)])
+    assert path.read() == output
+    assert retval == expected_retval
+
+
+def test_rewrite_crlf(tmpdir):
+    f = tmpdir.join('f.py')
+    f.write_binary(b'"foo"\r\n"bar"\r\n')
+    assert main((str(f),))
+    assert f.read_binary() == b"'foo'\r\n'bar'\r\n"