implement fluent (ftl) check

Fluent is file format used by Firefox and other programs for translation strings.

tests/check_fluent_test.py

@@ -0,0 +1,159 @@
+from __future__ import annotations
+
+import pytest
+
+from pre_commit_hooks.check_fluent import main
+
+
+def test_valid_fluent_file(tmp_path):
+    f = tmp_path / 'test.ftl'
+    f.write_text(
+        'hello = Hello, world!\n'
+        'greeting = Hello, { $name }!\n'
+        '    .title = Greeting\n'
+        'menu-item = Menu Item\n',
+    )
+    assert main([str(f)]) == 0
+
+
+def test_fluent_file_with_select_expression(tmp_path):
+    f = tmp_path / 'test.ftl'
+    f.write_text(
+        'emails = { $unreadEmails ->\n'
+        '    [0] You have no unread emails.\n'
+        '    [one] You have one unread email.\n'
+        '   *[other] You have { $unreadEmails } unread emails.\n'
+        '}\n',
+    )
+    assert main([str(f)]) == 0
+
+
+def test_fluent_file_with_comments(tmp_path):
+    f = tmp_path / 'test.ftl'
+    f.write_text(
+        '# This is a comment\n'
+        'hello = Hello, world!\n'
+        '\n'
+        '## Another comment\n'
+        'goodbye = Goodbye!\n',
+    )
+    assert main([str(f)]) == 0
+
+
+def test_fluent_file_with_invalid_identifier(tmp_path):
+    f = tmp_path / 'test.ftl'
+    f.write_text('123invalid = Invalid identifier\n')
+    assert main([str(f)]) == 1
+
+
+def test_fluent_file_with_invalid_attribute_identifier(tmp_path):
+    f = tmp_path / 'test.ftl'
+    f.write_text('hello = Hello\n' '    .123invalid = Invalid attribute\n')
+    assert main([str(f)]) == 1
+
+
+def test_fluent_file_missing_default_variant(tmp_path):
+    f = tmp_path / 'test.ftl'
+    f.write_text(
+        'emails = { $unreadEmails ->\n'
+        '    [0] You have no unread emails.\n'
+        '    [one] You have one unread email.\n'
+        '}\n',
+    )
+    assert main([str(f)]) == 1
+
+
+def test_fluent_file_variant_outside_select(tmp_path):
+    f = tmp_path / 'test.ftl'
+    f.write_text('hello = Hello\n' '   *[default] This should not be here\n')
+    assert main([str(f)]) == 1
+
+
+def test_fluent_file_missing_indentation(tmp_path):
+    f = tmp_path / 'test.ftl'
+    f.write_text('hello = Hello\n' '.title = This should be indented\n')
+    assert main([str(f)]) == 1
+
+
+def test_fluent_file_indented_without_context(tmp_path):
+    f = tmp_path / 'test.ftl'
+    f.write_text('    orphaned = This line has no message context\n')
+    assert main([str(f)]) == 1
+
+
+def test_non_utf8_file(tmp_path):
+    f = tmp_path / 'test.ftl'
+    f.write_bytes(b'\xa9\xfe\x12')
+    assert main([str(f)]) == 1
+
+
+def test_nonexistent_file():
+    assert main(['nonexistent.ftl']) == 1
+
+
+def test_empty_file(tmp_path):
+    f = tmp_path / 'test.ftl'
+    f.write_text('')
+    assert main([str(f)]) == 0
+
+
+def test_multiple_files(tmp_path):
+    f1 = tmp_path / 'valid.ftl'
+    f1.write_text('hello = Hello, world!\n')
+
+    f2 = tmp_path / 'invalid.ftl'
+    f2.write_text('123invalid = Invalid identifier\n')
+
+    assert main([str(f1), str(f2)]) == 1
+
+
+def test_multiple_valid_files(tmp_path):
+    f1 = tmp_path / 'valid1.ftl'
+    f1.write_text('hello = Hello, world!\n')
+
+    f2 = tmp_path / 'valid2.ftl'
+    f2.write_text('goodbye = Goodbye!\n')
+
+    assert main([str(f1), str(f2)]) == 0
+
+
+@pytest.mark.parametrize(
+    'identifier,expected',
+    [
+        ('hello', True),
+        ('hello-world', True),
+        ('hello_world', True),
+        ('hello123', True),
+        ('123hello', False),
+        ('hello-', True),
+        ('-hello', False),
+        ('', False),
+        ('hello.world', False),
+        ('hello world', False),
+    ],
+)
+def test_identifier_validation(identifier, expected):
+    from pre_commit_hooks.check_fluent import _is_valid_identifier
+
+    assert _is_valid_identifier(identifier) == expected
+
+
+def test_fluent_file_non_default_variant_with_closing_brace(tmp_path):
+    f = tmp_path / 'test.ftl'
+    f.write_text(
+        'emails = { $unreadEmails ->\n'
+        '    [0] You have no unread emails. }\n',
+    )
+    assert main([str(f)]) == 1  # Should fail due to missing default variant
+
+
+def test_fluent_file_non_star_variant_with_closing_check(tmp_path):
+    f = tmp_path / 'test.ftl'
+    f.write_text(
+        'test = { $var ->\n'
+        '    [case]\n'        # Comment
+        '        Value here\n'
+        '   *[other] Default\n'
+        '}\n',
+    )
+    assert main([str(f)]) == 0