add python.testing.cwd to pytest discovery if present (#24384)

fixes https://github.com/microsoft/vscode-python/issues/9553

src/client/testing/testController/pytest/pytestDiscoveryAdapter.ts

@@ -84,6 +84,9 @@ export class PytestTestDiscoveryAdapter implements ITestDiscoveryAdapter {
             traceWarn("Symlink found, adding '--rootdir' to pytestArgs only if it doesn't already exist. cwd: ", cwd);
             pytestArgs = addValueIfKeyNotExist(pytestArgs, '--rootdir', cwd);
         }
+        // if user has provided `--rootdir` then use that, otherwise add `cwd`
+        // root dir is required so pytest can find the relative paths and for symlinks
+        addValueIfKeyNotExist(pytestArgs, '--rootdir', cwd);
 
         // get and edit env vars
         const mutableEnv = {

src/test/testing/testController/pytest/pytestDiscoveryAdapter.unit.test.ts

@@ -179,7 +179,17 @@ suite('pytest test discovery adapter', () => {
 
         // verification
 
-        const expectedArgs = ['-m', 'pytest', '-p', 'vscode_pytest', '--collect-only', '.', 'abc', 'xyz'];
+        const expectedArgs = [
+            '-m',
+            'pytest',
+            '-p',
+            'vscode_pytest',
+            '--collect-only',
+            '.',
+            'abc',
+            'xyz',
+            `--rootdir=${expectedPathNew}`,
+        ];
         execService.verify(
             (x) =>
                 x.execObservable(