1 files changed, 103 insertions, 0 deletions
diff --git a/tests/trailing_whitespace_fixer_test.py b/tests/trailing_whitespace_fixer_test.py
new file mode 100644
index 0000000..c07497a
--- /dev/null
+++ b/tests/trailing_whitespace_fixer_test.py
@@ -0,0 +1,103 @@
+from __future__ import annotations
+
+import pytest
+
+from pre_commit_hooks.trailing_whitespace_fixer import main
+
+
+@pytest.mark.parametrize(
+    ('input_s', 'expected'),
+    (
+        ('foo \nbar \n', 'foo\nbar\n'),
+        ('bar\t\nbaz\t\n', 'bar\nbaz\n'),
+    ),
+)
+def test_fixes_trailing_whitespace(input_s, expected, tmpdir):
+    path = tmpdir.join('file.md')
+    path.write(input_s)
+    assert main((str(path),)) == 1
+    assert path.read() == expected
+
+
+def test_ok_no_newline_end_of_file(tmpdir):
+    filename = tmpdir.join('f')
+    filename.write_binary(b'foo\nbar')
+    ret = main((str(filename),))
+    assert filename.read_binary() == b'foo\nbar'
+    assert ret == 0
+
+
+def test_ok_with_dos_line_endings(tmpdir):
+    filename = tmpdir.join('f')
+    filename.write_binary(b'foo\r\nbar\r\nbaz\r\n')
+    ret = main((str(filename),))
+    assert filename.read_binary() == b'foo\r\nbar\r\nbaz\r\n'
+    assert ret == 0
+
+
+@pytest.mark.parametrize('ext', ('md', 'Md', '.md', '*'))
+def test_fixes_markdown_files(tmpdir, ext):
+    path = tmpdir.join('test.md')
+    path.write(
+        'foo  \n'  # leaves alone
+        'bar \n'  # less than two so it is removed
+        'baz    \n'  # more than two so it becomes two spaces
+        '\t\n'  # trailing tabs are stripped anyway
+        '\n  ',  # whitespace at the end of the file is removed
+    )
+    ret = main((str(path), f'--markdown-linebreak-ext={ext}'))
+    assert ret == 1
+    assert path.read() == (
+        'foo  \n'
+        'bar\n'
+        'baz  \n'
+        '\n'
+        '\n'
+    )
+
+
+@pytest.mark.parametrize('arg', ('--', 'a.b', 'a/b', ''))
+def test_markdown_linebreak_ext_badopt(arg):
+    with pytest.raises(SystemExit) as excinfo:
+        main(['--markdown-linebreak-ext', arg])
+    assert excinfo.value.code == 2
+
+
+def test_prints_warning_with_no_markdown_ext(capsys, tmpdir):
+    f = tmpdir.join('f').ensure()
+    assert main((str(f), '--no-markdown-linebreak-ext')) == 0
+    out, _ = capsys.readouterr()
+    assert out == '--no-markdown-linebreak-ext now does nothing!\n'
+
+
+def test_preserve_non_utf8_file(tmpdir):
+    non_utf8_bytes_content = b'<a>\xe9 \n</a>\n'
+    path = tmpdir.join('file.txt')
+    path.write_binary(non_utf8_bytes_content)
+    ret = main([str(path)])
+    assert ret == 1
+    assert path.size() == (len(non_utf8_bytes_content) - 1)
+
+
+def test_custom_charset_change(tmpdir):
+    # strip spaces only, no tabs
+    path = tmpdir.join('file.txt')
+    path.write('\ta \t \n')
+    ret = main([str(path), '--chars', ' '])
+    assert ret == 1
+    assert path.read() == '\ta \t\n'
+
+
+def test_custom_charset_no_change(tmpdir):
+    path = tmpdir.join('file.txt')
+    path.write('\ta \t\n')
+    ret = main([str(path), '--chars', ' '])
+    assert ret == 0
+
+
+def test_markdown_with_custom_charset(tmpdir):
+    path = tmpdir.join('file.md')
+    path.write('\ta \t   \n')
+    ret = main([str(path), '--chars', ' ', '--markdown-linebreak-ext', '*'])
+    assert ret == 1
+    assert path.read() == '\ta \t  \n'