File Patch MCP Server

"""Tests for generate_patch tool. Tests the patch generation functionality including: - Simple patch generation - Identical files (empty patch) - Binary file rejection - Symlink rejection - Custom context lines - Multiple hunks - File not found errors """ import pytest from pathlib import Path from patch_mcp.tools.generate import generate_patch class TestGeneratePatch: """Test suite for generate_patch tool.""" def test_generate_simple_patch(self, tmp_path): """Generate a simple patch with one change.""" # Create original file original = tmp_path / "original.txt" original.write_text("line1\nline2\nline3\n") # Create modified file modified = tmp_path / "modified.txt" modified.write_text("line1\nline2 modified\nline3\n") # Generate patch result = generate_patch(str(original), str(modified)) # Verify success assert result["success"] is True assert result["original_file"] == str(original) assert result["modified_file"] == str(modified) assert "patch" in result assert result["message"] == "Generated patch from file comparison" # Verify changes assert result["changes"]["lines_added"] == 1 assert result["changes"]["lines_removed"] == 1 assert result["changes"]["hunks"] == 1 # Verify patch format patch = result["patch"] assert "--- original.txt" in patch assert "+++ modified.txt" in patch assert "-line2" in patch assert "+line2 modified" in patch def test_generate_identical_files(self, tmp_path): """Generate patch from identical files should produce empty patch.""" # Create two identical files file1 = tmp_path / "file1.txt" file2 = tmp_path / "file2.txt" content = "same content\nline2\nline3\n" file1.write_text(content) file2.write_text(content) # Generate patch result = generate_patch(str(file1), str(file2)) # Verify success with empty patch assert result["success"] is True assert result["patch"] == "" assert result["changes"]["lines_added"] == 0 assert result["changes"]["lines_removed"] == 0 assert result["changes"]["hunks"] == 0 assert result["message"] == "Files are identical - no patch generated" def test_generate_reject_binary(self, tmp_path): """Binary files should be rejected.""" # Create binary file (contains null bytes) binary_file = tmp_path / "binary.dat" binary_file.write_bytes(b"\x00\x01\x02" * 100) # Create text file text_file = tmp_path / "text.txt" text_file.write_text("some text\n") # Test binary as original result = generate_patch(str(binary_file), str(text_file)) assert result["success"] is False assert result["error_type"] == "binary_file" assert "Original file" in result["error"] # Test binary as modified result = generate_patch(str(text_file), str(binary_file)) assert result["success"] is False assert result["error_type"] == "binary_file" assert "Modified file" in result["error"] def test_custom_context_lines(self, tmp_path): """Test custom number of context lines.""" # Create files with more lines original = tmp_path / "original.txt" original.write_text("line1\nline2\nline3\nline4\nline5\nline6\nline7\n") modified = tmp_path / "modified.txt" modified.write_text("line1\nline2\nchanged\nline4\nline5\nline6\nline7\n") # Generate with 1 context line result = generate_patch(str(original), str(modified), context_lines=1) assert result["success"] is True assert result["changes"]["hunks"] == 1 # Generate with 5 context lines result = generate_patch(str(original), str(modified), context_lines=5) assert result["success"] is True assert result["changes"]["hunks"] == 1 def test_generate_reject_symlink(self, tmp_path): """Symlinks should be rejected (security policy).""" # Create a real file real_file = tmp_path / "real.txt" real_file.write_text("content\n") # Create a symlink symlink = tmp_path / "link.txt" symlink.symlink_to(real_file) # Test symlink as original result = generate_patch(str(symlink), str(real_file)) assert result["success"] is False assert result["error_type"] == "symlink_error" assert "Original file" in result["error"] # Test symlink as modified result = generate_patch(str(real_file), str(symlink)) assert result["success"] is False assert result["error_type"] == "symlink_error" assert "Modified file" in result["error"] def test_generate_file_not_found(self, tmp_path): """Missing files should return file_not_found error.""" # Create one file existing = tmp_path / "exists.txt" existing.write_text("content\n") # Missing file missing = tmp_path / "missing.txt" # Test missing original result = generate_patch(str(missing), str(existing)) assert result["success"] is False assert result["error_type"] == "file_not_found" assert "Original file" in result["error"] # Test missing modified result = generate_patch(str(existing), str(missing)) assert result["success"] is False assert result["error_type"] == "file_not_found" assert "Modified file" in result["error"] def test_generate_multiple_hunks(self, tmp_path): """Generate patch with multiple hunks.""" # Create original file original = tmp_path / "original.txt" original.write_text( "line1\nline2\nline3\nline4\nline5\n" "line6\nline7\nline8\nline9\nline10\n" "line11\nline12\nline13\nline14\nline15\n" ) # Create modified file with changes in multiple locations modified = tmp_path / "modified.txt" modified.write_text( "line1 changed\nline2\nline3\nline4\nline5\n" "line6\nline7\nline8\nline9\nline10\n" "line11\nline12\nline13 changed\nline14\nline15\n" ) # Generate patch result = generate_patch(str(original), str(modified)) # Verify success assert result["success"] is True assert result["changes"]["lines_added"] == 2 assert result["changes"]["lines_removed"] == 2 assert result["changes"]["hunks"] == 2 def test_generate_addition_only(self, tmp_path): """Generate patch with only additions.""" # Create original file original = tmp_path / "original.txt" original.write_text("line1\nline2\n") # Create modified file with additions modified = tmp_path / "modified.txt" modified.write_text("line1\nline2\nline3\nline4\n") # Generate patch result = generate_patch(str(original), str(modified)) # Verify success assert result["success"] is True assert result["changes"]["lines_added"] == 2 assert result["changes"]["lines_removed"] == 0 assert result["changes"]["hunks"] == 1 def test_generate_removal_only(self, tmp_path): """Generate patch with only removals.""" # Create original file original = tmp_path / "original.txt" original.write_text("line1\nline2\nline3\nline4\n") # Create modified file with removals modified = tmp_path / "modified.txt" modified.write_text("line1\nline2\n") # Generate patch result = generate_patch(str(original), str(modified)) # Verify success assert result["success"] is True assert result["changes"]["lines_added"] == 0 assert result["changes"]["lines_removed"] == 2 assert result["changes"]["hunks"] == 1 def test_generate_encoding_error(self, tmp_path): """Non-UTF-8 files should be rejected (binary or encoding error).""" # Create file with invalid UTF-8 (high bytes trigger binary detection) bad_file = tmp_path / "bad.txt" bad_file.write_bytes(b"\x80\x81\x82\x83") # Invalid UTF-8 # Create good file good_file = tmp_path / "good.txt" good_file.write_text("content\n") # Test bad original - binary detection happens first result = generate_patch(str(bad_file), str(good_file)) assert result["success"] is False assert result["error_type"] in ["encoding_error", "binary_file"] # Test bad modified result = generate_patch(str(good_file), str(bad_file)) assert result["success"] is False assert result["error_type"] in ["encoding_error", "binary_file"] def test_generate_empty_files(self, tmp_path): """Generate patch from empty files.""" # Create two empty files file1 = tmp_path / "empty1.txt" file2 = tmp_path / "empty2.txt" file1.write_text("") file2.write_text("") # Generate patch result = generate_patch(str(file1), str(file2)) # Should succeed with no changes assert result["success"] is True assert result["changes"]["hunks"] == 0 assert result["patch"] == ""