Edited Discovery Logic (#20631)

closes #20078 and
closes #20085 (which is
about the testing work to support this code)

This logic now successfully works to discover the pytest repo tests.
This branch takes into account all the previous comments made to the
python discovery logic in the previous PR (located on my personal fork).
Therefore this is a second round of edits on this code. It now works for
the pytest library (discovers all the tests in the pytest library).

---------

Co-authored-by: Brett Cannon <brcan@microsoft.com>
Co-authored-by: Karthik Nadig <kanadig@microsoft.com>

.vscode/launch.json

@@ -253,6 +253,15 @@
             "request": "attach",
             "listen": { "host": "localhost", "port": 5678 },
             "justMyCode": true
+        },
+        {
+            "name": "Debug pytest plugin tests",
+
+            "type": "python",
+            "request": "launch",
+            "module": "pytest",
+            "args": ["${workspaceFolder}/pythonFiles/tests/pytestadapter"],
+            "justMyCode": true
         }
     ],
     "compounds": [

pythonFiles/tests/pytestadapter/.data/double_nested_folder/nested_folder_one/nested_folder_two/test_nest.py

@@ -0,0 +1,8 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.
+
+
+# This test's id is double_nested_folder/nested_folder_one/nested_folder_two/test_nest.py::test_function.
+# This test passes.
+def test_function():  # test_marker--test_function
+    assert 1 == 1

pythonFiles/tests/pytestadapter/.data/dual_level_nested_folder/nested_folder_one/test_bottom_folder.py

@@ -0,0 +1,14 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.
+
+
+# This test's id is dual_level_nested_folder/nested_folder_one/test_bottom_folder.py::test_bottom_function_t.
+# This test passes.
+def test_bottom_function_t():  # test_marker--test_bottom_function_t
+    assert True
+
+
+# This test's id is dual_level_nested_folder/nested_folder_one/test_bottom_folder.py::test_bottom_function_f.
+# This test fails.
+def test_bottom_function_f():  # test_marker--test_bottom_function_f
+    assert False

pythonFiles/tests/pytestadapter/.data/dual_level_nested_folder/test_top_folder.py

@@ -0,0 +1,14 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.
+
+
+# This test's id is dual_level_nested_folder/test_top_folder.py::test_top_function_t.
+# This test passes.
+def test_top_function_t():  # test_marker--test_top_function_t
+    assert True
+
+
+# This test's id is dual_level_nested_folder/test_top_folder.py::test_top_function_f.
+# This test fails.
+def test_top_function_f():  # test_marker--test_top_function_f
+    assert False

pythonFiles/tests/pytestadapter/.data/empty_discovery.py

@@ -0,0 +1,7 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.
+
+
+# This file has no tests in it; the discovery will return an empty list of tests.
+def function_function(string):
+    return string

pythonFiles/tests/pytestadapter/.data/error_parametrize_discovery.py

@@ -0,0 +1,10 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.
+import pytest
+
+
+# This test has an error which will appear on pytest discovery.
+# This error is intentional and is meant to test pytest discovery error handling.
+@pytest.mark.parametrize("actual,expected", [("3+5", 8), ("2+4", 6), ("6*9", 42)])
+def test_function():
+    assert True

pythonFiles/tests/pytestadapter/.data/error_syntax_discovery.txt

@@ -0,0 +1,7 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.
+
+# This test has a syntax error.
+# This error is intentional and is meant to test pytest discovery error handling.
+def test_function()
+    assert True

pythonFiles/tests/pytestadapter/.data/parametrize_tests.py

@@ -0,0 +1,10 @@
+import pytest
+
+
+# Testing pytest with parametrized tests. The first two pass, the third fails.
+# The tests ids are parametrize_tests.py::test_adding[3+5-8] and so on.
+@pytest.mark.parametrize(  # test_marker--test_adding
+    "actual, expected", [("3+5", 8), ("2+4", 6), ("6+9", 16)]
+)
+def test_adding(actual, expected):
+    assert eval(actual) == expected

pythonFiles/tests/pytestadapter/.data/simple_pytest.py

@@ -0,0 +1,7 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.
+
+
+# This test passes.
+def test_function():  # test_marker--test_function
+    assert 1 == 1

pythonFiles/tests/pytestadapter/.data/text_docstring.txt

@@ -0,0 +1,4 @@
+This is a doctest test which passes #test_marker--text_docstring.txt
+>>> x = 3
+>>> x
+3

pythonFiles/tests/pytestadapter/.data/unittest_folder/test_add.py

@@ -0,0 +1,21 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.
+import unittest
+
+
+def add(a, b):
+    return a + b
+
+
+class TestAddFunction(unittest.TestCase):
+    # This test's id is unittest_folder/test_add.py::TestAddFunction::test_add_positive_numbers.
+    # This test passes.
+    def test_add_positive_numbers(self):  # test_marker--test_add_positive_numbers
+        result = add(2, 3)
+        self.assertEqual(result, 5)
+
+    # This test's id is unittest_folder/test_add.py::TestAddFunction::test_add_negative_numbers.
+    # This test passes.
+    def test_add_negative_numbers(self):  # test_marker--test_add_negative_numbers
+        result = add(-2, -3)
+        self.assertEqual(result, -5)

pythonFiles/tests/pytestadapter/.data/unittest_folder/test_subtract.py

@@ -0,0 +1,25 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.
+import unittest
+
+
+def subtract(a, b):
+    return a - b
+
+
+class TestSubtractFunction(unittest.TestCase):
+    # This test's id is unittest_folder/test_subtract.py::TestSubtractFunction::test_subtract_positive_numbers.
+    # This test passes.
+    def test_subtract_positive_numbers(  # test_marker--test_subtract_positive_numbers
+        self,
+    ):
+        result = subtract(5, 3)
+        self.assertEqual(result, 2)
+
+    # This test's id is unittest_folder/test_subtract.py::TestSubtractFunction::test_subtract_negative_numbers.
+    # This test passes.
+    def test_subtract_negative_numbers(  # test_marker--test_subtract_negative_numbers
+        self,
+    ):
+        result = subtract(-2, -3)
+        self.assertEqual(result, 1)

pythonFiles/tests/pytestadapter/.data/unittest_pytest_same_file.py

@@ -0,0 +1,17 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.
+
+import unittest
+
+
+class TestExample(unittest.TestCase):
+    # This test's id is unittest_pytest_same_file.py::TestExample::test_true_unittest.
+    # Test type is unittest and this test passes.
+    def test_true_unittest(self):  # test_marker--test_true_unittest
+        assert True
+
+
+# This test's id is unittest_pytest_same_file.py::test_true_pytest.
+# Test type is pytest and this test passes.
+def test_true_pytest():  # test_marker--test_true_pytest
+    assert True

pythonFiles/tests/pytestadapter/__init__.py

@@ -0,0 +1,2 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.