Fix precedence in parsePyTestModuleCollectionResult

[tammoippen]

For ...

• Pull request represents a single change (i.e. not fixing disparate/unrelated things in a single PR)
• Title summarizes what is changing
• Has a news entry file (remember to thank yourself!)
• Has sufficient logging.
• Has telemetry for enhancements.
• Unit tests & system/integration tests are added/updated
• Test plan is updated as appropriate
• package-lock.json has been regenerated by running npm install (if dependencies have changed)

When discovering tests with pytest, the Python Test Log ended with:

Test Discovery failed: 
TypeError: Cannot read property 'item' of undefined

The developer console gives me:

[Extension Host] Python Extension: displayDiscoverStatus TypeError: Cannot read property 'item' of undefined
	at module.exports.l.parsePyTestModuleCollectionResult.t.forEach.t (/Users/tammoippen/.vscode/extensions/ms-python.python-2019.1.0/out/client/extension.js:77591:45)
	at Array.forEach (<anonymous>)
	at l.parsePyTestModuleCollectionResult (/Users/tammoippen/.vscode/extensions/ms-python.python-2019.1.0/out/client/extension.js:77527:11)
	at module.exports.l.getTestFiles.e.split.forEach (/Users/tammoippen/.vscode/extensions/ms-python.python-2019.1.0/out/client/extension.js:77463:23)
	at Array.forEach (<anonymous>)
	at l.getTestFiles (/Users/tammoippen/.vscode/extensions/ms-python.python-2019.1.0/out/client/extension.js:77458:29)
	at l.parse (/Users/tammoippen/.vscode/extensions/ms-python.python-2019.1.0/out/client/extension.js:77445:24)
	at h.<anonymous> (/Users/tammoippen/.vscode/extensions/ms-python.python-2019.1.0/out/client/extension.js:77387:31)
	at Generator.next (<anonymous>)
	at s (/Users/tammoippen/.vscode/extensions/ms-python.python-2019.1.0/out/client/extension.js:77303:21)

Which pointed me to parsePyTestModuleCollectionResult and parentNode not being correctly guarded (undefined in my case).

[msftclas]

All CLA requirements met.

[codecov]

Codecov Report

Merging #4360 into master will increase coverage by 22%.
The diff coverage is 100%.

@@           Coverage Diff            @@
##           master   #4360     +/-   ##
========================================
+ Coverage      56%     78%    +22%     
========================================
  Files         361     439     +78     
  Lines       15274   20515   +5241     
  Branches     2373    3288    +915     
========================================
+ Hits         8494   15805   +7311     
+ Misses       6236    4706   -1530     
+ Partials      544       4    -540

Flag	Coverage Δ
#Linux	66% <100%> (?)
#Windows	66% <100%> (?)
#macOS	66% <100%> (?)

[tammoippen]

After tempering with my tests, I think the issue occurs with newer pytests and tests with multiline docstrings and using verbose output. See here aswell: pytest-dev/pytest#4582. I think this breaks the parser?