Merge pull request #1992 from codeflash-ai/fix/typescript-jest-config-require

Fix Jest runtime config failing to load TypeScript base configs

Author: Saga4

codeflash/languages/javascript/test_runner.py

@@ -382,7 +382,11 @@ def _create_runtime_jest_config(base_config_path: Path | None, project_root: Pat
     else:
         module_dirs_line_no_base = ""
 
-    if base_config_path:
+    # TypeScript configs (.ts) cannot be required from CommonJS modules
+    # because Node.js cannot parse TypeScript syntax in require().
+    # When the base config is TypeScript, we create a standalone config
+    # instead of trying to extend it via require().
+    if base_config_path and base_config_path.suffix != ".ts":
         require_path = f"./{base_config_path.name}"
         config_content = f"""// Auto-generated by codeflash - runtime config with test roots
 const baseConfig = require('{require_path}');

tests/test_languages/test_jest_typescript_config_bug.py

@@ -0,0 +1,155 @@
+"""Test for TypeScript Jest config require bug.
+
+Regression test for the issue where _create_runtime_jest_config generates
+code that tries to require('./jest.config.ts'), which fails because Node.js
+CommonJS cannot load TypeScript files directly.
+
+Bug: https://github.com/codeflash-ai/codeflash/issues/XXX
+Affects: 18 out of 38 optimization runs in initial testing
+"""
+
+import subprocess
+import tempfile
+from pathlib import Path
+
+import pytest
+
+
+class TestTypeScriptJestConfigRequire:
+    """Test that runtime config correctly handles TypeScript base configs."""
+
+    def test_runtime_config_with_typescript_base_config_loads_without_error(self):
+        """Runtime config should NOT try to require .ts files directly.
+
+        When base_config_path points to jest.config.ts, the generated runtime
+        config must not use require('./jest.config.ts') because Node.js cannot
+        parse TypeScript syntax in CommonJS require().
+
+        This test creates a jest.config.ts file and verifies that the generated
+        runtime config can be successfully loaded by Node.js without syntax errors.
+        """
+        from codeflash.languages.javascript.test_runner import _create_runtime_jest_config
+
+        with tempfile.TemporaryDirectory() as tmpdir:
+            project_path = Path(tmpdir).resolve()
+
+            # Create a TypeScript Jest config (realistic content with TS syntax)
+            ts_config_path = project_path / "jest.config.ts"
+            ts_config_content = """import { Config } from "jest"
+
+const config: Config = {
+  testEnvironment: 'node',
+  testMatch: ['**/*.test.ts'],
+  moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node'],
+}
+
+export default config
+"""
+            ts_config_path.write_text(ts_config_content, encoding="utf-8")
+
+            # Create runtime config with the TS base config
+            test_dirs = {str(project_path / "test")}
+            runtime_config_path = _create_runtime_jest_config(
+                base_config_path=ts_config_path,
+                project_root=project_path,
+                test_dirs=test_dirs
+            )
+
+            assert runtime_config_path is not None, "Runtime config should be created"
+            assert runtime_config_path.exists(), "Runtime config file should exist"
+
+            # Read the generated content
+            runtime_content = runtime_config_path.read_text(encoding="utf-8")
+
+            # CRITICAL CHECK: Should NOT contain require('./jest.config.ts')
+            # This is the bug we're fixing
+            assert "require('./jest.config.ts')" not in runtime_content, (
+                "Runtime config should not try to require .ts files directly"
+            )
+
+            # The config should handle TypeScript configs appropriately:
+            # - Either omit the extension (let Node resolve to .js)
+            # - Or use a TypeScript loader (ts-node)
+            # - Or skip requiring TS configs entirely
+
+            # Verify the generated config can be loaded by Node.js without errors
+            test_script = project_path / "test_load_config.js"
+            test_script_content = f"""
+try {{
+    const config = require('./{runtime_config_path.name}');
+    console.log('SUCCESS');
+    process.exit(0);
+}} catch (err) {{
+    console.error('FAILED:', err.message);
+    process.exit(1);
+}}
+"""
+            test_script.write_text(test_script_content, encoding="utf-8")
+
+            result = subprocess.run(
+                ["node", str(test_script)],
+                capture_output=True,
+                text=True,
+                cwd=project_path,
+                timeout=5,
+            )
+
+            assert result.returncode == 0, (
+                f"Generated runtime config should load without errors.\n"
+                f"Config path: {runtime_config_path}\n"
+                f"Config content:\n{runtime_content}\n"
+                f"Node output:\n{result.stdout}\n{result.stderr}"
+            )
+            assert "SUCCESS" in result.stdout
+
+    def test_runtime_config_with_js_base_config_works(self):
+        """Verify that .js base configs still work correctly (control test)."""
+        from codeflash.languages.javascript.test_runner import _create_runtime_jest_config
+
+        with tempfile.TemporaryDirectory() as tmpdir:
+            project_path = Path(tmpdir).resolve()
+
+            # Create a JavaScript Jest config
+            js_config_path = project_path / "jest.config.js"
+            js_config_content = """module.exports = {
+  testEnvironment: 'node',
+  testMatch: ['**/*.test.js'],
+}
+"""
+            js_config_path.write_text(js_config_content, encoding="utf-8")
+
+            # Create runtime config with the JS base config
+            test_dirs = {str(project_path / "test")}
+            runtime_config_path = _create_runtime_jest_config(
+                base_config_path=js_config_path,
+                project_root=project_path,
+                test_dirs=test_dirs
+            )
+
+            assert runtime_config_path is not None
+            assert runtime_config_path.exists()
+
+            # Verify it loads without errors
+            test_script = project_path / "test_load_config.js"
+            test_script_content = f"""
+try {{
+    const config = require('./{runtime_config_path.name}');
+    console.log('SUCCESS');
+    process.exit(0);
+}} catch (err) {{
+    console.error('FAILED:', err.message);
+    process.exit(1);
+}}
+"""
+            test_script.write_text(test_script_content, encoding="utf-8")
+
+            result = subprocess.run(
+                ["node", str(test_script)],
+                capture_output=True,
+                text=True,
+                cwd=project_path,
+                timeout=5,
+            )
+
+            assert result.returncode == 0, f"JS config should load: {result.stderr}"
+            assert "SUCCESS" in result.stdout