From 54a13cbb7ad931d4d23dd8768dee4a2cbe4543f2 Mon Sep 17 00:00:00 2001
From: 7000pctAUTO <lukems3823@gmail.com>
Date: Mon, 2 Feb 2026 17:24:43 +0000
Subject: [PATCH] Add tests - part 2

---
 tests/test_diff.py | 116 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 116 insertions(+)
 create mode 100644 tests/test_diff.py

diff --git a/tests/test_diff.py b/tests/test_diff.py
new file mode 100644
index 0000000..ae54942
--- /dev/null
+++ b/tests/test_diff.py
@@ -0,0 +1,116 @@
+"""Tests for diff generation."""
+
+
+from i18n_guardian.diff.diff_generator import DiffGenerator, DiffChange, DiffResult
+
+
+class TestDiffGenerator:
+    """Tests for DiffGenerator."""
+
+    def test_generate_diff_basic(self, temp_dir):
+        """Test basic diff generation."""
+        file_path = temp_dir / "test.py"
+        old_content = 'message = "Hello"'
+        new_content = 'message = t("Hello")'
+
+        generator = DiffGenerator()
+        diff = generator.generate_diff(file_path, old_content, new_content)
+
+        assert isinstance(diff, str)
+        assert len(diff) > 0
+        assert "---" in diff
+        assert "+++" in diff
+        assert "-" in diff
+        assert "+" in diff
+
+    def test_generate_diff_multiple_lines(self, temp_dir):
+        """Test diff generation for multiple lines."""
+        file_path = temp_dir / "test.py"
+        old_content = '''def greet():
+    return "Hello"
+'''
+        new_content = '''def greet():
+    return t("Hello")
+'''
+
+        generator = DiffGenerator()
+        diff = generator.generate_diff(file_path, old_content, new_content)
+
+        assert "Hello" in diff
+
+    def test_create_replacement(self):
+        """Test creating replacement string with i18n function."""
+        generator = DiffGenerator()
+        replacement = generator.create_replacement("Hello World", "t")
+
+        assert 't("Hello World")' in replacement
+        assert "\\n" not in replacement or replacement.count('\\n') == 0
+
+    def test_create_replacement_escaping(self):
+        """Test that special characters are escaped."""
+        generator = DiffGenerator()
+        replacement = generator.create_replacement('Hello "World"', "t")
+
+        assert '\\"' in replacement
+
+    def test_diff_result_structure(self):
+        """Test DiffResult has correct structure."""
+        result = DiffResult()
+        assert hasattr(result, "changes")
+        assert hasattr(result, "files_modified")
+        assert hasattr(result, "total_changes")
+        assert result.changes == []
+
+    def test_diff_change_structure(self, temp_dir):
+        """Test DiffChange has correct structure."""
+        change = DiffChange(
+            file_path=temp_dir / "test.py",
+            original_line=1,
+            original_text='"Hello"',
+            new_text='t("Hello")',
+        )
+
+        assert hasattr(change, "file_path")
+        assert hasattr(change, "original_line")
+        assert hasattr(change, "original_text")
+        assert hasattr(change, "new_text")
+
+    def test_empty_diff(self, temp_dir):
+        """Test diff with no changes."""
+        file_path = temp_dir / "test.py"
+        content = 'message = "Hello"'
+
+        generator = DiffGenerator()
+        diff = generator.generate_diff(file_path, content, content)
+
+        assert isinstance(diff, str)
+
+    def test_apply_diff_creates_backup(self, temp_dir):
+        """Test that applying diff creates backup."""
+        file_path = temp_dir / "test.py"
+        file_path.write_text('message = "Hello"', encoding="utf-8")
+
+        old_content = file_path.read_text(encoding="utf-8")
+        new_content = 'message = t("Hello")'
+
+        generator = DiffGenerator()
+        diff = generator.generate_diff(file_path, old_content, new_content)
+        result = generator.apply_diff(file_path, diff, backup=True)
+
+        assert result
+        assert file_path.with_suffix(".bak").exists()
+
+    def test_apply_diff_modifies_file(self, temp_dir):
+        """Test that applying diff modifies file."""
+        file_path = temp_dir / "test.py"
+        file_path.write_text('message = "Hello"', encoding="utf-8")
+
+        old_content = file_path.read_text(encoding="utf-8")
+        new_content = 'message = t("Hello")'
+
+        generator = DiffGenerator()
+        diff = generator.generate_diff(file_path, old_content, new_content)
+        generator.apply_diff(file_path, diff, backup=False)
+
+        content = file_path.read_text(encoding="utf-8")
+        assert 't("Hello")' in content