test: add unit tests for node_modules symlink in JS worktree setup

Covers setup_test_config symlinking node_modules from original repo
to worktree, including edge cases (no worktree, missing node_modules,
already existing node_modules).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/test_languages/test_javascript_setup_test_config.py

@@ -0,0 +1,149 @@
+from pathlib import Path
+from unittest.mock import patch
+
+import pytest
+
+from codeflash.languages.javascript.support import JavaScriptSupport
+from codeflash.verification.verification_utils import TestConfig
+
+
+@pytest.fixture
+def js_support() -> JavaScriptSupport:
+    return JavaScriptSupport()
+
+
+def make_test_config(project_root: Path) -> TestConfig:
+    return TestConfig(
+        tests_root=project_root / "tests",
+        project_root_path=project_root,
+        tests_project_rootdir=project_root,
+    )
+
+
+class TestSetupTestConfigNodeModulesSymlink:
+    def test_symlinks_node_modules_when_worktree_and_original_exists(self, js_support: JavaScriptSupport, tmp_path: Path) -> None:
+        original_root = tmp_path / "original"
+        worktree_root = tmp_path / "worktree"
+
+        original_root.mkdir()
+        worktree_root.mkdir()
+
+        # Create package.json in worktree so find_node_project_root finds it
+        (worktree_root / "package.json").write_text("{}", encoding="utf-8")
+
+        # Create node_modules in original
+        original_node_modules = original_root / "node_modules"
+        original_node_modules.mkdir()
+        (original_node_modules / "some_package").mkdir()
+
+        test_cfg = make_test_config(worktree_root)
+        file_path = worktree_root / "src" / "index.js"
+        file_path.parent.mkdir(parents=True, exist_ok=True)
+        file_path.touch()
+
+        with (
+            patch("codeflash.languages.javascript.support.git_root_dir", return_value=worktree_root),
+            patch("codeflash.languages.javascript.support.mirror_path", return_value=original_root),
+            patch("codeflash.languages.javascript.optimizer.verify_js_requirements"),
+        ):
+            js_support.setup_test_config(test_cfg, file_path, current_worktree=original_root)
+
+        worktree_node_modules = test_cfg.js_project_root / "node_modules"
+        assert worktree_node_modules.is_symlink()
+        assert worktree_node_modules.resolve() == original_node_modules.resolve()
+
+    def test_no_symlink_when_worktree_is_none(self, js_support: JavaScriptSupport, tmp_path: Path) -> None:
+        project_root = tmp_path / "project"
+        project_root.mkdir()
+        (project_root / "package.json").write_text("{}", encoding="utf-8")
+
+        # Create node_modules in project (should remain a real directory, not a symlink)
+        (project_root / "node_modules").mkdir()
+
+        test_cfg = make_test_config(project_root)
+        file_path = project_root / "index.js"
+        file_path.touch()
+
+        with patch("codeflash.languages.javascript.optimizer.verify_js_requirements"):
+            js_support.setup_test_config(test_cfg, file_path, current_worktree=None)
+
+        assert not (project_root / "node_modules").is_symlink()
+
+    def test_no_symlink_when_original_node_modules_missing(self, js_support: JavaScriptSupport, tmp_path: Path) -> None:
+        original_root = tmp_path / "original"
+        worktree_root = tmp_path / "worktree"
+
+        original_root.mkdir()
+        worktree_root.mkdir()
+        (worktree_root / "package.json").write_text("{}", encoding="utf-8")
+
+        # Do NOT create node_modules in original
+        test_cfg = make_test_config(worktree_root)
+        file_path = worktree_root / "index.js"
+        file_path.touch()
+
+        with (
+            patch("codeflash.languages.javascript.support.git_root_dir", return_value=worktree_root),
+            patch("codeflash.languages.javascript.support.mirror_path", return_value=original_root),
+            patch("codeflash.languages.javascript.optimizer.verify_js_requirements"),
+        ):
+            js_support.setup_test_config(test_cfg, file_path, current_worktree=original_root)
+
+        worktree_node_modules = test_cfg.js_project_root / "node_modules"
+        assert not worktree_node_modules.exists()
+        assert not worktree_node_modules.is_symlink()
+
+    def test_no_symlink_when_worktree_node_modules_already_exists(self, js_support: JavaScriptSupport, tmp_path: Path) -> None:
+        original_root = tmp_path / "original"
+        worktree_root = tmp_path / "worktree"
+
+        original_root.mkdir()
+        worktree_root.mkdir()
+        (worktree_root / "package.json").write_text("{}", encoding="utf-8")
+
+        # Create node_modules in both
+        (original_root / "node_modules").mkdir()
+        (worktree_root / "node_modules").mkdir()
+
+        test_cfg = make_test_config(worktree_root)
+        file_path = worktree_root / "index.js"
+        file_path.touch()
+
+        with (
+            patch("codeflash.languages.javascript.support.git_root_dir", return_value=worktree_root),
+            patch("codeflash.languages.javascript.support.mirror_path", return_value=original_root),
+            patch("codeflash.languages.javascript.optimizer.verify_js_requirements"),
+        ):
+            js_support.setup_test_config(test_cfg, file_path, current_worktree=original_root)
+
+        worktree_node_modules = test_cfg.js_project_root / "node_modules"
+        assert not worktree_node_modules.is_symlink()
+        assert worktree_node_modules.is_dir()
+
+    def test_symlink_points_to_correct_target(self, js_support: JavaScriptSupport, tmp_path: Path) -> None:
+        original_root = tmp_path / "original"
+        worktree_root = tmp_path / "worktree"
+
+        original_root.mkdir()
+        worktree_root.mkdir()
+        (worktree_root / "package.json").write_text("{}", encoding="utf-8")
+
+        original_node_modules = original_root / "node_modules"
+        original_node_modules.mkdir()
+        # Add a marker file to verify the symlink target is correct
+        (original_node_modules / "marker.txt").write_text("test", encoding="utf-8")
+
+        test_cfg = make_test_config(worktree_root)
+        file_path = worktree_root / "index.js"
+        file_path.touch()
+
+        with (
+            patch("codeflash.languages.javascript.support.git_root_dir", return_value=worktree_root),
+            patch("codeflash.languages.javascript.support.mirror_path", return_value=original_root),
+            patch("codeflash.languages.javascript.optimizer.verify_js_requirements"),
+        ):
+            js_support.setup_test_config(test_cfg, file_path, current_worktree=original_root)
+
+        worktree_node_modules = test_cfg.js_project_root / "node_modules"
+        assert worktree_node_modules.is_symlink()
+        assert (worktree_node_modules / "marker.txt").read_text(encoding="utf-8") == "test"