fix: set tests_project_rootdir to tests_root for Java projects

Bug #2: Test file name mapping returns null for Java tests

Root cause: For Java projects, tests_project_rootdir was incorrectly set
to the project root instead of the actual tests directory. This caused
test file resolution to fail in parse_test_xml when parsing JUnit XML
from Maven Surefire, which doesn't include file attributes.

JavaScript already had this fix (line 654), but Java was missing it.

Fix: Add Java to the language check that sets tests_project_rootdir
equal to tests_root, ensuring instrumented test files can be found at
src/test/java/com/example/Test__perfinstrumented.java

Changes:
- Added is_java import to discover_unit_tests.py
- Added Java check: if is_java(): cfg.tests_project_rootdir = cfg.tests_root
- Added comprehensive test coverage with 2 test cases

Tests:
- test_java_tests_project_rootdir_set_to_tests_root: verifies fix for Java
- test_python_tests_project_rootdir_unchanged: verifies Python unchanged

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

codeflash/discovery/discover_unit_tests.py

@@ -641,17 +641,20 @@ def discover_unit_tests(
     discover_only_these_tests: list[Path] | None = None,
     file_to_funcs_to_optimize: dict[Path, list[FunctionToOptimize]] | None = None,
 ) -> tuple[dict[str, set[FunctionCalledInTest]], int, int]:
-    from codeflash.languages import is_javascript, is_python
+    from codeflash.languages import is_java, is_javascript, is_python
 
     # Detect language from functions being optimized
     language = _detect_language_from_functions(file_to_funcs_to_optimize)
 
     # Route to language-specific test discovery for non-Python languages
     if not is_python():
-        # For JavaScript/TypeScript, tests_project_rootdir should be tests_root itself
+        # For JavaScript/TypeScript and Java, tests_project_rootdir should be tests_root itself
         # The Jest helper will be configured to NOT include "tests." prefix to match
+        # For Java, this ensures test file resolution works correctly in parse_test_xml
         if is_javascript():
             cfg.tests_project_rootdir = cfg.tests_root
+        if is_java():
+            cfg.tests_project_rootdir = cfg.tests_root
         return discover_tests_for_language(cfg, language, file_to_funcs_to_optimize)
 
     # Existing Python logic

tests/test_java_tests_project_rootdir.py

@@ -0,0 +1,82 @@
+"""Test that tests_project_rootdir is set correctly for Java projects."""
+
+from pathlib import Path
+from unittest.mock import MagicMock, patch
+
+from codeflash.discovery.discover_unit_tests import discover_unit_tests
+from codeflash.languages.base import Language
+from codeflash.languages.current import set_current_language
+from codeflash.verification.verification_utils import TestConfig
+
+
+def test_java_tests_project_rootdir_set_to_tests_root(tmp_path):
+    """Test that for Java projects, tests_project_rootdir is set to tests_root."""
+    # Create a mock Java project structure
+    project_root = tmp_path / "project"
+    project_root.mkdir()
+    (project_root / "pom.xml").touch()
+
+    tests_root = project_root / "src" / "test" / "java"
+    tests_root.mkdir(parents=True)
+
+    # Create test config with tests_project_rootdir initially set to project root
+    # (simulating what happens before the fix)
+    test_cfg = TestConfig(
+        tests_root=tests_root,
+        project_root_path=project_root,
+        tests_project_rootdir=project_root,  # Initially set to project root
+    )
+
+    # Create a mock Java function to ensure language detection works
+    mock_java_function = MagicMock()
+    mock_java_function.language = "java"
+    file_to_funcs = {Path("dummy.java"): [mock_java_function]}
+
+    # Mock is_python() to return False and is_java() to return True
+    # These are imported from codeflash.languages
+    with patch("codeflash.languages.is_python", return_value=False), \
+         patch("codeflash.languages.is_java", return_value=True), \
+         patch("codeflash.discovery.discover_unit_tests.discover_tests_for_language") as mock_discover:
+        mock_discover.return_value = ({}, 0, 0)
+
+        # Call discover_unit_tests
+        discover_unit_tests(test_cfg, file_to_funcs_to_optimize=file_to_funcs)
+
+    # Verify that tests_project_rootdir was updated to tests_root
+    assert test_cfg.tests_project_rootdir == tests_root, (
+        f"Expected tests_project_rootdir to be {tests_root}, "
+        f"but got {test_cfg.tests_project_rootdir}"
+    )
+
+
+def test_python_tests_project_rootdir_unchanged(tmp_path):
+    """Test that for Python projects, tests_project_rootdir behavior is unchanged."""
+    # Setup Python environment
+    set_current_language(Language.PYTHON)
+
+    # Create a mock Python project structure
+    project_root = tmp_path / "project"
+    project_root.mkdir()
+    (project_root / "pyproject.toml").touch()
+
+    tests_root = project_root / "tests"
+    tests_root.mkdir()
+
+    # Create test config
+    original_tests_project_rootdir = project_root / "some" / "other" / "dir"
+    test_cfg = TestConfig(
+        tests_root=tests_root,
+        project_root_path=project_root,
+        tests_project_rootdir=original_tests_project_rootdir,
+    )
+
+    # Mock pytest discovery
+    with patch("codeflash.discovery.discover_unit_tests.discover_tests_pytest") as mock_discover:
+        mock_discover.return_value = ({}, 0, 0)
+
+        # Call discover_unit_tests
+        discover_unit_tests(test_cfg, file_to_funcs_to_optimize={})
+
+    # For Python, tests_project_rootdir should remain unchanged
+    # (the function doesn't modify it for Python projects)
+    assert test_cfg.tests_project_rootdir == original_tests_project_rootdir