pytest Test Explorer reports a test as passed when only its first subTest passes (later subtest failures are ignored)

[dkt-jpgoodwin]

Type: Bug

Behaviour

When a unittest.TestCase test uses self.subTest(...) in a loop and runs through the pytest adapter, the Test Explorer shows the test as passed as soon as the first subtest passes. Failures in later subtests are ignored.

Running the same test from the command line (python -m pytest -v) correctly reports SUBFAIL entries and exits with a non-zero code.

Environment

• VS Code: 1.140.0
• Python extension (ms-python.python): 2026.6.0
• Python: 3.14
• pytest: 9.1.1, which supports unittest.TestCase.subTest natively. No pytest-subtests plugin is installed.
• OS: macOS 26.4

Expected: the test is marked as failed, ideally with one result per subtest.
Actual: the test is marked as passed, and later subtest failures appear nowhere in the Test Explorer.

Root cause analysis (python_files/vscode_pytest/__init__.py)

• pytest_report_teststatus sends one result per nodeid and skips every later report for an id already present in collected_tests_so_far.
• With pytest ≥ 9, every subtest emits its own report with when == "call" and the same nodeid as its parent test. The first subtest's report, here a pass, is sent, and all following subtest reports, including failures, are dropped.
• pytest_exception_interact uses the same filtering.
• create_test_outcome ignores its subtype argument and always sets subtest=None.

Suggested fix: detect subtest reports (pytest ≥ 9 SubtestReport, or reports that carry a subtest context) and send them with a distinct id such as <nodeid> [msg] (params), filling the subtest field like the unittest adapter does. At a minimum, a failed subtest must mark its parent test as failed.

Workaround: switch to the unittest adapter (python.testing.unittestEnabled: true), which reports subtests correctly.

Steps to reproduce:

1. Create a project with pytest 9.1.1 and enable pytest as the test runner (python.testing.pytestEnabled: true).
2. Add the following test file:

   import unittest
   
   class TestSubtests(unittest.TestCase):
       def test_loop(self):
           for i in range(3):
               with self.subTest("case", i=i):
                   self.assertEqual(i, 0)

3. Discover the tests, then run test_loop from the Test Explorer.
4. Observe that test_loop is shown as passed.
5. Run python -m pytest -v in a terminal and observe that the i=1 and i=2 subtests fail:

   [paste the output showing SUBPASS / SUBFAIL lines]
   

Diagnostic data

Output for Python in the Output panel (View→Output, change the drop-down the upper-right of the Output panel to Python)

XXX

Extension version: 2026.6.0
VS Code version: Code 1.139.1 (Universal) (04c0d99f4fb0d8afe6ce4f0c58e31e183ac3e4b1, 2026-09-25T03:40:57Z)
OS version: Darwin arm64 25.4.0
Modes:

System Info

Item	Value
CPUs	Apple M1 Pro (8 x 2400)
GPU Status	2d_canvas: enabled GPU0: VENDOR= 0x106b [Google Inc. (Apple)], DEVICE=0x0000 [ANGLE (Apple, ANGLE Metal Renderer: Apple M1 Pro, Version 26.4 (Build 25E246))], DRIVER_VENDOR=Apple, DRIVER_VERSION=26.4 ACTIVE Machine model name: MacBookPro Machine model version: 18.3 direct_rendering_display_compositor: disabled_off_ok gpu_compositing: enabled multiple_raster_threads: enabled_on opengl: enabled_on rasterization: enabled raw_draw: disabled_off_ok skia_graphite: enabled_on trees_in_viz: disabled_off video_decode: enabled video_encode: enabled webgl: enabled webgpu: enabled webnn: disabled_off
Load (avg)	9, 11, 12
Memory (System)	16.00GB (0.09GB free)
Process Argv	--crash-reporter-id 8e09e954-95f8-4519-a8a2-83eedbae3d44
Screen Reader	no
VM	0%

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