File Patch MCP Server

"""Tests for revert_patch tool. Tests the patch reversion functionality including: - Successful reversion - Reversion after file modification - Reversion with multiple hunks - Edge cases """ import pytest from pathlib import Path from patch_mcp.tools.apply import apply_patch from patch_mcp.tools.revert import revert_patch class TestRevertPatch: """Test suite for revert_patch tool.""" def test_revert_success(self, tmp_path): """Apply then revert should restore original content.""" # Create file file = tmp_path / "config.py" original_content = "DEBUG = False\nLOG_LEVEL = 'INFO'\nPORT = 8000\n" file.write_text(original_content) # Create and apply patch patch = """--- config.py +++ config.py @@ -1,3 +1,3 @@ DEBUG = False -LOG_LEVEL = 'INFO' +LOG_LEVEL = 'DEBUG' PORT = 8000 """ # Apply patch apply_result = apply_patch(str(file), patch) assert apply_result["success"] is True # Verify file was modified assert file.read_text() != original_content assert "LOG_LEVEL = 'DEBUG'" in file.read_text() # Revert patch revert_result = revert_patch(str(file), patch) # Verify success assert revert_result["success"] is True assert revert_result["file_path"] == str(file) assert revert_result["reverted"] is True assert "Successfully reverted" in revert_result["message"] # Verify changes (opposite of apply) assert revert_result["changes"]["lines_added"] == 1 assert revert_result["changes"]["lines_removed"] == 1 assert revert_result["changes"]["hunks_reverted"] == 1 # CRITICAL: File should be back to original assert file.read_text() == original_content def test_revert_after_modification(self, tmp_path): """Revert should fail if file was modified after patch.""" # Create file and apply patch file = tmp_path / "config.py" file.write_text("DEBUG = False\nLOG_LEVEL = 'INFO'\nPORT = 8000\n") patch = """--- config.py +++ config.py @@ -1,3 +1,3 @@ DEBUG = False -LOG_LEVEL = 'INFO' +LOG_LEVEL = 'DEBUG' PORT = 8000 """ apply_result = apply_patch(str(file), patch) assert apply_result["success"] is True # Modify file in the same area file.write_text("DEBUG = False\nLOG_LEVEL = 'WARNING'\nPORT = 8000\n") # Try to revert - should fail revert_result = revert_patch(str(file), patch) # Should fail with context mismatch assert revert_result["success"] is False assert revert_result["reverted"] is False assert revert_result["error_type"] == "context_mismatch" assert "modified" in revert_result["error"].lower() def test_revert_file_not_found(self, tmp_path): """Revert on missing file should fail.""" missing = tmp_path / "missing.txt" patch = """--- missing.txt +++ missing.txt @@ -1,1 +1,1 @@ -old +new """ result = revert_patch(str(missing), patch) assert result["success"] is False assert result["reverted"] is False assert result["error_type"] == "file_not_found" def test_revert_unchanged_if_already_reverted(self, tmp_path): """Reverting twice should fail (file already in original state).""" # Create file file = tmp_path / "file.py" original = "line1\nline2\nline3\n" file.write_text(original) patch = """--- file.py +++ file.py @@ -1,3 +1,3 @@ line1 -line2 +modified line3 """ # Apply and revert apply_patch(str(file), patch) revert_patch(str(file), patch) # File is back to original assert file.read_text() == original # Try to revert again - should fail result = revert_patch(str(file), patch) # Should fail because patch expects "modified" but finds "line2" assert result["success"] is False assert result["reverted"] is False def test_revert_multiple_hunks(self, tmp_path): """Revert patch with multiple hunks.""" file = tmp_path / "file.py" original = ( "line1\nline2\nline3\nline4\nline5\n" "line6\nline7\nline8\nline9\nline10\n" ) file.write_text(original) patch = """--- file.py +++ file.py @@ -1,3 +1,3 @@ -line1 +line1 modified line2 line3 @@ -8,3 +8,3 @@ line8 -line9 +line9 modified line10 """ # Apply patch apply_result = apply_patch(str(file), patch) assert apply_result["success"] is True # Revert patch revert_result = revert_patch(str(file), patch) assert revert_result["success"] is True assert revert_result["changes"]["hunks_reverted"] == 2 # File should be back to original assert file.read_text() == original def test_revert_addition_only(self, tmp_path): """Revert patch that only added lines.""" file = tmp_path / "file.py" original = "line1\nline2\n" file.write_text(original) # Patch adds a line patch = """--- file.py +++ file.py @@ -1,2 +1,3 @@ line1 +added line2 """ # Apply (adds line) apply_patch(str(file), patch) assert "added" in file.read_text() # Revert (removes line) revert_result = revert_patch(str(file), patch) assert revert_result["success"] is True # When reverting an addition, we remove it assert revert_result["changes"]["lines_removed"] == 1 assert revert_result["changes"]["lines_added"] == 0 # File back to original assert file.read_text() == original def test_revert_removal_only(self, tmp_path): """Revert patch that only removed lines.""" file = tmp_path / "file.py" original = "line1\nremove_me\nline2\n" file.write_text(original) # Patch removes a line patch = """--- file.py +++ file.py @@ -1,3 +1,2 @@ line1 -remove_me line2 """ # Apply (removes line) apply_patch(str(file), patch) assert "remove_me" not in file.read_text() # Revert (adds it back) revert_result = revert_patch(str(file), patch) assert revert_result["success"] is True # When reverting a removal, we add it back assert revert_result["changes"]["lines_added"] == 1 assert revert_result["changes"]["lines_removed"] == 0 # File back to original assert file.read_text() == original def test_revert_empty_patch(self, tmp_path): """Reverting an empty patch should succeed.""" file = tmp_path / "file.txt" content = "content\n" file.write_text(content) result = revert_patch(str(file), "") # Should succeed (no-op) assert result["success"] is True assert result["changes"]["hunks_reverted"] == 0 # File unchanged assert file.read_text() == content def test_revert_complex_patch(self, tmp_path): """Revert complex patch with mixed operations.""" file = tmp_path / "complex.py" original = "def foo():\n old1\n old2\n keep\n" file.write_text(original) patch = """--- complex.py +++ complex.py @@ -1,4 +1,4 @@ def foo(): - old1 - old2 + new1 + new2 keep """ # Apply apply_patch(str(file), patch) modified = file.read_text() assert "new1" in modified assert "new2" in modified assert "old1" not in modified # Revert result = revert_patch(str(file), patch) assert result["success"] is True # Back to original assert file.read_text() == original def test_revert_preserves_error_type(self, tmp_path): """Error types from apply should be preserved.""" # Create symlink real_file = tmp_path / "real.txt" real_file.write_text("content\n") symlink = tmp_path / "link.txt" symlink.symlink_to(real_file) patch = """--- link.txt +++ link.txt @@ -1,1 +1,1 @@ -content +modified """ result = revert_patch(str(symlink), patch) # Should preserve symlink_error from apply assert result["success"] is False assert result["error_type"] == "symlink_error" def test_revert_with_whitespace_changes(self, tmp_path): """Revert whitespace-only changes.""" file = tmp_path / "file.py" original = "line1\nline2\nline3\n" file.write_text(original) # Add trailing space patch = """--- file.py +++ file.py @@ -1,3 +1,3 @@ line1 -line2 +line2 line3 """ # Apply apply_patch(str(file), patch) # Revert result = revert_patch(str(file), patch) assert result["success"] is True # Should restore exact original (including whitespace) assert file.read_text() == original def test_revert_sequential_patches(self, tmp_path): """Test reverting patches in reverse order.""" file = tmp_path / "file.py" v0 = "version0\n" file.write_text(v0) patch1 = """--- file.py +++ file.py @@ -1,1 +1,1 @@ -version0 +version1 """ patch2 = """--- file.py +++ file.py @@ -1,1 +1,1 @@ -version1 +version2 """ # Apply both patches apply_patch(str(file), patch1) assert "version1" in file.read_text() apply_patch(str(file), patch2) assert "version2" in file.read_text() # Revert in reverse order (last applied first) revert_patch(str(file), patch2) assert "version1" in file.read_text() revert_patch(str(file), patch1) assert file.read_text() == v0