pytest 5.1.0 seems to break the test adapter

[krazyace78]

Issue Type: Bug

After updating VSCode from v1.36.1 to v1.37.1 (in WSL), pytest unit tests are no longer displaying green/red status in the side bar. An error pop-up is displayed with the following message:

There was an error in running the tests.
Source Python (Extension)

The OUTPUT tab indicates that the test passed, but there is also an error message that seems like it is related to the extension issue:

============================= test session starts ==============================
platform linux -- Python 3.6.8, pytest-5.1.0, py-1.8.0, pluggy-0.12.0
rootdir: /mnt/c/Users/.../
plugins: cov-2.7.1
collected 1 item

tests/test___init__.py .                                                 [100%]

-------------- generated xml file: /tmp/tmp-2499XLU6ay233ncl.xml ---------------
============================== 1 passed in 0.06s ===============================
Error: TypeError: Cannot read property '$' of undefined

Extension version: 2019.8.30787
VS Code version: Code 1.37.1 (f06011ac164ae4dc8e753a3fe7f9549844d15e35, 2019-08-15T16:17:55.855Z)
OS version: Windows_NT x64 10.0.17134
Remote OS version: Linux x64 4.4.0-17134-Microsoft

System Info

Item	Value
CPUs	Intel(R) Xeon(R) CPU X5650 @ 2.67GHz (12 x 3800)
GPU Status	2d_canvas: enabled flash_3d: enabled flash_stage3d: enabled flash_stage3d_baseline: enabled gpu_compositing: enabled multiple_raster_threads: enabled_on native_gpu_memory_buffers: disabled_software oop_rasterization: disabled_off protected_video_decode: unavailable_off rasterization: enabled skia_deferred_display_list: disabled_off skia_renderer: disabled_off surface_synchronization: enabled_on video_decode: enabled viz_display_compositor: disabled_off webgl: enabled webgl2: enabled
Load (avg)	undefined
Memory (System)	24.00GB (14.93GB free)
Process Argv	--folder-uri=vscode-remote://wsl+default/mnt/c/Users/.../ --remote=wsl+default
Screen Reader	no
VM	50%

Item	Value
Remote	WSL
OS	Linux x64 4.4.0-17134-Microsoft
CPUs	Intel(R) Xeon(R) CPU X5650 @ 2.67GHz (12 x 3800)
Memory (System)	24.00GB (14.93GB free)
VM	50%

[marsfan]

@krazyace78 @pvscbot

Also mentioning @Johnnyxy and @BLeAm as I see they posted a reaction to it.

I have the same issue.
I believe this is unrelated to updating Visual Studio Code. I just ran some tests, and the issue seems to be with pytest 5.1.0.

Try downgrading to pytest 5.0.1 (via pip install -U pytest==5.0.1), as that fixed it for me.
Attached is my output from the developer console:

onDidNotificationChange @ notificationsAlerts.ts:40
_register.model.onDidNotificationChange.e @ notificationsAlerts.ts:26
fire @ event.ts:572
addNotification @ notifications.ts:156
notify @ notificationService.ts:55
r @ mainThreadMessageService.ts:83
_showMessage @ mainThreadMessageService.ts:44
$showMessage @ mainThreadMessageService.ts:38
_doInvokeHandler @ rpcProtocol.ts:394
_invokeHandler @ rpcProtocol.ts:379
_receiveRequest @ rpcProtocol.ts:299
_receiveOneMessage @ rpcProtocol.ts:226
_protocol.onMessage.e @ rpcProtocol.ts:101
fire @ event.ts:572
a @ ipc.net.ts:421
e @ ipc.net.ts:428
fire @ event.ts:572
_receiveMessage @ ipc.net.ts:715
S._socketDisposables.push._socketReader.onMessage.e @ ipc.net.ts:578
fire @ event.ts:572
acceptChunk @ ipc.net.ts:236
_register._socket.onData.e @ ipc.net.ts:197
t @ ipc.net.ts:28
emit @ events.js:182
addChunk @ _stream_readable.js:283
readableAddChunk @ _stream_readable.js:264
Readable.push @ _stream_readable.js:219
onStreamRead @ internal/stream_base_commons.js:94
notificationsAlerts.ts:38 Error: Cannot read property '$' of undefined
	at module.exports.i.readFile.n.parseString (c:\Users\Gabe\.vscode\extensions\ms-python.python-2019.8.30787\out\client\extension.js:75:948003)
	at l.<anonymous> (c:\Users\Gabe\.vscode\extensions\ms-python.python-2019.8.30787\out\client\node_modules\xml2js.js:1:50429)
	at l.emit (events.js:182:13)
	at i.onclosetag (c:\Users\Gabe\.vscode\extensions\ms-python.python-2019.8.30787\out\client\node_modules\xml2js.js:1:49765)
	at I (c:\Users\Gabe\.vscode\extensions\ms-python.python-2019.8.30787\out\client\node_modules\xml2js.js:2:6036)
	at A (c:\Users\Gabe\.vscode\extensions\ms-python.python-2019.8.30787\out\client\node_modules\xml2js.js:2:6075)
	at M (c:\Users\Gabe\.vscode\extensions\ms-python.python-2019.8.30787\out\client\node_modules\xml2js.js:2:9359)
	at i.write (c:\Users\Gabe\.vscode\extensions\ms-python.python-2019.8.30787\out\client\node_modules\xml2js.js:1:58596)
	at l.module.exports.904.e.Parser.l.parseString (c:\Users\Gabe\.vscode\extensions\ms-python.python-2019.8.30787\out\client\node_modules\xml2js.js:1:50669)
	at l.module.exports.904.h [as parseString] (c:\Users\Gabe\.vscode\extensions\ms-python.python-2019.8.30787\out\client\node_modules\xml2js.js:1:45293)
	at Object.module.exports.904.e.parseString (c:\Users\Gabe\.vscode\extensions\ms-python.python-2019.8.30787\out\client\node_modules\xml2js.js:1:51007)
	at module.exports.i.readFile (c:\Users\Gabe\.vscode\extensions\ms-python.python-2019.8.30787\out\client\extension.js:75:947919)
	at FSReqWrap.readFileAfterClose [as oncomplete] (internal/fs/read_file_context.js:53:3)```

[marsfan]

Upon further examination, the output between 5.1.0 and 5.0.1 seems to be the same, so I do not know why this would trigger an error, but I know that downgrading to 5.0.1 fixed it for me.

[BLeAm]

@marsfan Thank you for mentioning me and the workaround.

[krazyace78]

Thank you for the workaround @marsfan!

[vthorsteinsson]

I have the same issue, and the workaround did the trick for me. Thanks @marsfan!

[cornel-masson]

+1 works for me now @marsfan
In case someone has the same issues: to downgrade pytest to 5.0.1, uninstall it first (e.g. pipenv uninstall pytest), then add the dependency in your Pipfile as "<=5.0.1" and re-install (e.g. pipenv install pytest).

[Johnnyxy]

Additionally, if you do not use any environments:

global install: pip install --force-reinstall pytest==5.0.1

user install: pip install --user --force-reinstall pytest==5.0.1