Fix: Recalculate js_project_root per function in monorepos

codeflash/languages/function_optimizer.py

@@ -3085,6 +3085,16 @@ def run_optimized_candidate(
                 )
             )
 
+    def get_js_project_root(self) -> Path | None:
+        # Only calculate for JavaScript/TypeScript projects
+        if self.function_to_optimize.language not in ("javascript", "typescript"):
+            return self.test_cfg.js_project_root  # Fall back to cached value for non-JS
+
+        # For JS/TS, calculate fresh for each function to support monorepos
+        from codeflash.languages.javascript.test_runner import find_node_project_root
+
+        return find_node_project_root(Path(self.function_to_optimize.file_path))
+
     def run_and_parse_tests(
         self,
         testing_type: TestingMode,
@@ -3103,33 +3113,39 @@ def run_and_parse_tests(
         coverage_config_file = None
         try:
             if testing_type == TestingMode.BEHAVIOR:
+                # Calculate js_project_root for the current function being optimized
+                # instead of using cached value from test_cfg, which may be from a different function
+                js_project_root = self.get_js_project_root()
+
                 result_file_path, run_result, coverage_database_file, coverage_config_file = (
                     self.language_support.run_behavioral_tests(
                         test_paths=test_files,
                         test_env=test_env,
                         cwd=self.project_root,
                         timeout=INDIVIDUAL_TESTCASE_TIMEOUT,
-                        project_root=self.test_cfg.js_project_root,
+                        project_root=js_project_root,
                         enable_coverage=enable_coverage,
                         candidate_index=optimization_iteration,
                     )
                 )
             elif testing_type == TestingMode.LINE_PROFILE:
+                js_project_root = self.get_js_project_root()
                 result_file_path, run_result = self.language_support.run_line_profile_tests(
                     test_paths=test_files,
                     test_env=test_env,
                     cwd=self.project_root,
                     timeout=INDIVIDUAL_TESTCASE_TIMEOUT,
-                    project_root=self.test_cfg.js_project_root,
+                    project_root=js_project_root,
                     line_profile_output_file=line_profiler_output_file,
                 )
             elif testing_type == TestingMode.PERFORMANCE:
+                js_project_root = self.get_js_project_root()
                 result_file_path, run_result = self.language_support.run_benchmarking_tests(
                     test_paths=test_files,
                     test_env=test_env,
                     cwd=self.project_root,
                     timeout=INDIVIDUAL_TESTCASE_TIMEOUT,
-                    project_root=self.test_cfg.js_project_root,
+                    project_root=js_project_root,
                     min_loops=pytest_min_loops,
                     max_loops=pytest_max_loops,
                     target_duration_seconds=testing_time,

tests/test_js_project_root_per_function.py

@@ -0,0 +1,66 @@
+"""Test that js_project_root is recalculated per function, not cached."""
+
+from pathlib import Path
+
+from codeflash.languages.javascript.test_runner import find_node_project_root
+
+
+def test_find_node_project_root_returns_different_roots_for_different_files(tmp_path: Path) -> None:
+    """Test that find_node_project_root returns the correct root for each file."""
+    # Create main project structure
+    main_project = (tmp_path / "project").resolve()
+    main_project.mkdir()
+    (main_project / "package.json").write_text("{}", encoding="utf-8")
+    (main_project / "src").mkdir()
+    main_file = (main_project / "src" / "main.ts").resolve()
+    main_file.write_text("// main file", encoding="utf-8")
+
+    # Create extension subdirectory with its own package.json
+    extension_dir = (main_project / "extensions" / "discord").resolve()
+    extension_dir.mkdir(parents=True)
+    (extension_dir / "package.json").write_text("{}", encoding="utf-8")
+    (extension_dir / "src").mkdir()
+    extension_file = (extension_dir / "src" / "accounts.ts").resolve()
+    extension_file.write_text("// extension file", encoding="utf-8")
+
+    # Extension file should return extension directory
+    result1 = find_node_project_root(extension_file)
+    assert result1 == extension_dir, f"Expected {extension_dir}, got {result1}"
+
+    # Main file should return main project directory
+    result2 = find_node_project_root(main_file)
+    assert result2 == main_project, f"Expected {main_project}, got {result2}"
+
+    # Calling again with extension file should still return extension dir
+    result3 = find_node_project_root(extension_file)
+    assert result3 == extension_dir, f"Expected {extension_dir}, got {result3}"
+
+
+def test_js_project_root_recalculated_per_function(tmp_path: Path) -> None:
+    """Each function in a monorepo should resolve to its own nearest package.json root."""
+    # Create main project
+    main_project = (tmp_path / "project").resolve()
+    main_project.mkdir()
+    (main_project / "package.json").write_text('{"name": "main"}', encoding="utf-8")
+    (main_project / "src").mkdir()
+
+    # Create extension with its own package.json
+    extension_dir = (main_project / "extensions" / "discord").resolve()
+    extension_dir.mkdir(parents=True)
+    (extension_dir / "package.json").write_text('{"name": "discord-extension"}', encoding="utf-8")
+    (extension_dir / "src").mkdir()
+
+    extension_file = (extension_dir / "src" / "accounts.ts").resolve()
+    extension_file.write_text("export function foo() {}", encoding="utf-8")
+
+    main_file = (main_project / "src" / "commands.ts").resolve()
+    main_file.write_text("export function bar() {}", encoding="utf-8")
+
+    js_project_root_1 = find_node_project_root(extension_file)
+    assert js_project_root_1 == extension_dir
+
+    js_project_root_2 = find_node_project_root(main_file)
+    assert js_project_root_2 == main_project, (
+        f"Expected {main_project}, got {js_project_root_2}. "
+        f"Happens when js_project_root is not recalculated per function."
+    )

tests/test_optimizer_js_project_root_bug.py

@@ -0,0 +1,57 @@
+"""Test that test_cfg.js_project_root caching bug is demonstrated and bypassed by the fix."""
+
+from pathlib import Path
+from unittest.mock import patch
+
+from codeflash.languages.javascript.support import JavaScriptSupport
+from codeflash.verification.verification_utils import TestConfig
+
+
+@patch("codeflash.languages.javascript.optimizer.verify_js_requirements")
+def test_js_project_root_cached_in_test_cfg(mock_verify: object, tmp_path: Path) -> None:
+    """Demonstrates that test_cfg.js_project_root is set once per setup_test_config call.
+
+    This test shows the root cause: test_cfg caches the project root from the first function.
+    The fix bypasses this cache in FunctionOptimizer.get_js_project_root() instead of
+    changing how test_cfg stores the value.
+    """
+    mock_verify.return_value = []  # type: ignore[attr-defined]
+
+    # Create main project
+    main_project = (tmp_path / "project").resolve()
+    main_project.mkdir()
+    (main_project / "package.json").write_text('{"name": "main"}', encoding="utf-8")
+    (main_project / "src").mkdir()
+    (main_project / "test").mkdir()
+    (main_project / "node_modules").mkdir()
+
+    # Create extension with its own package.json
+    extension_dir = (main_project / "extensions" / "discord").resolve()
+    extension_dir.mkdir(parents=True)
+    (extension_dir / "package.json").write_text('{"name": "discord-extension"}', encoding="utf-8")
+    (extension_dir / "src").mkdir()
+    (extension_dir / "node_modules").mkdir()
+
+    test_cfg = TestConfig(
+        tests_root=main_project / "test",
+        project_root_path=main_project,
+        tests_project_rootdir=main_project / "test",
+    )
+    test_cfg.set_language("javascript")
+
+    js_support = JavaScriptSupport()
+
+    extension_file = (extension_dir / "src" / "accounts.ts").resolve()
+    extension_file.write_text("export function foo() {}", encoding="utf-8")
+
+    success = js_support.setup_test_config(test_cfg, extension_file, current_worktree=None)
+    assert success, "setup_test_config should succeed"
+    # After setup for extension file, js_project_root is the extension directory
+    assert test_cfg.js_project_root == extension_dir
+
+    # test_cfg is NOT re-initialized for subsequent functions — js_project_root stays cached
+    main_file = (main_project / "src" / "commands.ts").resolve()
+    main_file.write_text("export function bar() {}", encoding="utf-8")
+
+    # The cached value is still extension_dir, not main_project — this is the root cause
+    assert test_cfg.js_project_root == extension_dir