fix(testing): propagate PROJECT_ROOT_PATH and PYTHONPATH during test debugging

python_files/tests/unittestadapter/test_execution.py

@@ -472,3 +472,44 @@ def test_symlink_with_project_root_path(mock_send_run_data) -> None:  # noqa: AR
         assert actual["cwd"] == os.fsdecode(destination), (
             f"CWD does not match symlink path: expected {os.fsdecode(destination)}, got {actual['cwd']}"
         )
+
+
+def test_project_root_path_defaults_top_level_dir(mock_send_run_data) -> None:  # noqa: ARG001
+    """Test that project_root_path acts as top_level_dir during execution when start_dir is a subdir.
+
+    When tests are in a subdirectory (e.g. ./test_outer_folder/test_inner_folder) and top_level_dir
+    is None, passing project_root_path as top_level_dir ensures the discovered test IDs match
+    those discovered during the discovery phase.
+    """
+    project_path = TEST_DATA_PATH / "utils_complex_tree"
+    start_dir = os.fsdecode(
+        pathlib.PurePath(
+            TEST_DATA_PATH,
+            "utils_complex_tree",
+            "test_outer_folder",
+            "test_inner_folder",
+        )
+    )
+    pattern = "test_*.py"
+    top_level_dir = os.fsdecode(project_path)
+    test_ids = [
+        "test_outer_folder.test_inner_folder.test_utils_complex_tree.TreeOne.test_one",
+    ]
+
+    os.environ["TEST_RUN_PIPE"] = "fake"
+
+    actual = run_tests(
+        start_dir,
+        test_ids,
+        pattern,
+        None,
+        1,
+        None,
+        project_root_path=top_level_dir,
+    )
+
+    assert actual["status"] == "success"
+    assert actual["cwd"] == os.fsdecode(project_path)
+    assert actual["result"] is not None
+    assert test_ids[0] in actual["result"]
+    assert actual["result"][test_ids[0]]["outcome"] == "success"

python_files/unittestadapter/discovery.py

@@ -142,9 +142,10 @@ def discover_tests(
             raise VSCodeUnittestError(error_msg)  # noqa: B904
     else:
         # Check for PROJECT_ROOT_PATH environment variable (project-based testing).
-        # When set, this overrides top_level_dir to root the test tree at the project directory.
+        # When set, this overrides top_level_dir to root the test tree at the project directory
+        # if an explicit top-level directory was not provided.
         project_root_path = os.environ.get("PROJECT_ROOT_PATH")
-        if project_root_path:
+        if project_root_path and not top_level_dir:
             top_level_dir = project_root_path
 
         # Perform regular unittest test discovery.

python_files/unittestadapter/execution.py

@@ -210,6 +210,8 @@ def run_tests(
                           (used for project-based testing to root test tree at project)
     """
     cwd = os.path.abspath(project_root_path or start_dir)  # noqa: PTH100
+    if top_level_dir is None and project_root_path:
+        top_level_dir = project_root_path
     if "/" in start_dir:  #  is a subdir
         parent_dir = os.path.dirname(start_dir)  # noqa: PTH120
         sys.path.insert(0, parent_dir)
@@ -373,6 +375,8 @@ def send_run_data(raw_data, test_run_pipe):
             # Update the module-level variable for send_run_data to use
             # pylint: disable=global-statement
             globals()["PROJECT_ROOT_PATH"] = project_root_path
+            if not top_level_dir:
+                top_level_dir = project_root_path
 
         # Perform regular unittest execution.
         # Pass project_root_path so the payload's cwd matches the project root.

src/client/testing/common/debugLauncher.ts

@@ -311,6 +311,10 @@ export class DebugLauncher implements ITestDebugLauncher {
             );
         }
 
+        if (options.project) {
+            launchArgs.env.PROJECT_ROOT_PATH = options.project.uri.fsPath;
+        }
+
         const pluginPath = path.join(EXTENSION_ROOT_DIR, 'python_files');
         // check if PYTHONPATH is already set in the environment variables
         if (launchArgs.env) {
@@ -322,7 +326,7 @@ export class DebugLauncher implements ITestDebugLauncher {
             }
             // add the plugin path or cwd to PYTHONPATH if it is not already there using the following function
             // this function will handle if PYTHONPATH is undefined
-            addPathToPythonpath(additionalPythonPath, launchArgs.env.PYTHONPATH);
+            launchArgs.env.PYTHONPATH = addPathToPythonpath(additionalPythonPath, launchArgs.env.PYTHONPATH);
         }
 
         // Clear out purpose so we can detect if the configuration was used to

src/test/testing/common/debugLauncher.unit.test.ts

@@ -793,6 +793,8 @@ suite('Unit Tests - Debug Launcher', () => {
 
             expect(capturedConfigs).to.have.length(1);
             expect(capturedConfigs[0].name).to.equal('Debug Tests: myproject (Python 3.11)');
+            expect(capturedConfigs[0].env?.PROJECT_ROOT_PATH).to.equal(Uri.file('one/two/three').fsPath);
+            expect(capturedConfigs[0].env?.PYTHONPATH).to.include(path.join(EXTENSION_ROOT_DIR, 'python_files'));
         });
 
         test('should use default python when no project provided', async () => {
@@ -812,6 +814,8 @@ suite('Unit Tests - Debug Launcher', () => {
             expect(capturedConfigs).to.have.length(1);
             // Should use the default 'python' from interpreterService mock
             expect(capturedConfigs[0].python).to.equal('python');
+            expect(capturedConfigs[0].env?.PROJECT_ROOT_PATH).to.be.undefined;
+            expect(capturedConfigs[0].env?.PYTHONPATH).to.include(path.join(EXTENSION_ROOT_DIR, 'python_files'));
         });
 
         test('should add unique session marker to launch config', async () => {