fix(js): pass project Jest config for TypeScript transformation

When running generated tests on TypeScript projects, Jest was failing
with "unexpected token" errors because it wasn't configured to transform
TypeScript files. The tests were being run without the project's Jest
config file.

This fix:
- Adds `_find_jest_config()` function to locate Jest config files
- Searches project root and parent directories (for monorepo support)
- Passes `--config` flag to Jest in all test runner functions
- Stops search at git root or monorepo root (package.json with workspaces)

Tested against next.js (monorepo) where jest.config.js is at repo root
but packages are in nested directories.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: misrasaurabh1

codeflash/languages/javascript/test_runner.py

@@ -47,6 +47,73 @@ def _find_node_project_root(file_path: Path) -> Path | None:
     return None
 
 
+def _find_jest_config(project_root: Path) -> Path | None:
+    """Find Jest configuration file in the project.
+
+    Searches for common Jest config file names in the project root and parent
+    directories (for monorepo support). This is important for TypeScript projects
+    that require specific transformation configurations (e.g., next/jest, ts-jest, babel-jest).
+
+    Args:
+        project_root: Root of the project to search.
+
+    Returns:
+        Path to Jest config file, or None if not found.
+
+    """
+    # Common Jest config file names, in order of preference
+    config_names = [
+        "jest.config.ts",
+        "jest.config.js",
+        "jest.config.mjs",
+        "jest.config.cjs",
+        "jest.config.json",
+    ]
+
+    # First check the project root itself
+    for config_name in config_names:
+        config_path = project_root / config_name
+        if config_path.exists():
+            logger.debug(f"Found Jest config: {config_path}")
+            return config_path
+
+    # For monorepos, search parent directories up to the filesystem root
+    # Stop at common monorepo root indicators (git root, package.json with workspaces)
+    current = project_root.parent
+    max_depth = 5  # Don't search too far up
+    depth = 0
+
+    while current != current.parent and depth < max_depth:
+        for config_name in config_names:
+            config_path = current / config_name
+            if config_path.exists():
+                logger.debug(f"Found Jest config in parent directory: {config_path}")
+                return config_path
+
+        # Check if this looks like a monorepo root
+        package_json = current / "package.json"
+        if package_json.exists():
+            try:
+                import json
+
+                with package_json.open("r") as f:
+                    pkg = json.load(f)
+                    if "workspaces" in pkg:
+                        # This is likely the monorepo root, stop here
+                        break
+            except Exception:
+                pass
+
+        # Check for git root as another stopping point
+        if (current / ".git").exists():
+            break
+
+        current = current.parent
+        depth += 1
+
+    return None
+
+
 def _is_esm_project(project_root: Path) -> bool:
     """Check if the project uses ES Modules.
 
@@ -230,6 +297,11 @@ def run_jest_behavioral_tests(
         "--forceExit",
     ]
 
+    # Add Jest config if found - needed for TypeScript transformation
+    jest_config = _find_jest_config(effective_cwd)
+    if jest_config:
+        jest_cmd.append(f"--config={jest_config}")
+
     # Add coverage flags if enabled
     if enable_coverage:
         jest_cmd.extend(["--coverage", "--coverageReporters=json", f"--coverageDirectory={coverage_dir}"])
@@ -459,6 +531,11 @@ def run_jest_benchmarking_tests(
         "--runner=codeflash/loop-runner",  # Use custom loop runner for in-process looping
     ]
 
+    # Add Jest config if found - needed for TypeScript transformation
+    jest_config = _find_jest_config(effective_cwd)
+    if jest_config:
+        jest_cmd.append(f"--config={jest_config}")
+
     if test_files:
         jest_cmd.append("--runTestsByPath")
         resolved_test_files = [str(Path(f).resolve()) for f in test_files]
@@ -593,6 +670,11 @@ def run_jest_line_profile_tests(
         "--forceExit",
     ]
 
+    # Add Jest config if found - needed for TypeScript transformation
+    jest_config = _find_jest_config(effective_cwd)
+    if jest_config:
+        jest_cmd.append(f"--config={jest_config}")
+
     if test_files:
         jest_cmd.append("--runTestsByPath")
         resolved_test_files = [str(Path(f).resolve()) for f in test_files]