Fix discovery of PyTests with packages inbetween folders

[Flamefire]

For #3936

• 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!)
• Unit tests & system/integration tests are added/updated
• Test plan is updated as appropriate
• [x]~ package-lock.json has been regenerated by running npm install (if dependencies have changed)~

[msftclas]

All CLA requirements met.

[codecov]

Codecov Report

Merging #3937 into master will increase coverage by 1%.
The diff coverage is 100%.

@@          Coverage Diff           @@
##           master   #3937   +/-   ##
======================================
+ Coverage      78%     78%   +1%     
======================================
  Files         402     402           
  Lines       18568   18574    +6     
  Branches     2983    2985    +2     
======================================
+ Hits        14350   14356    +6     
  Misses       4216    4216           
  Partials        2       2

Flag	Coverage Δ
#Linux	68% <59%> (ø)	⬇️
#Windows	68% <59%> (ø)	⬇️
#macOS	68% <59%> (ø)	⬇️

Impacted Files	Coverage Δ
.../client/unittests/pytest/services/parserService.ts	81% <100%> (+1%)	⬆️

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[Flamefire]

@DonJayamanne It passes all but 1 test where the remaining one is a download failure on travis. Could you have a look at the code?

[DonJayamanne]

@Flamefire
Thanks for the PR, unfortunately the latest version of PyTest breaks all of the test discovery and we have plans to change this code. I.e. even if we merged your changes, it will become redundant this sprint.
The issue used to re-write the discovery in python is being tracked in #4033

[Flamefire]

@DonJayamanne any update on this? I've seen #4098 was merged containing a fix for pytest 4.1 based on the current discovery and #3911 is no longer a P1 issue. Seems like the refactoring won't happen soon and discovery stays broken for e.g. my use case making this unusable.

[DonJayamanne]

Seems like the refactoring won't happen soon and discovery stays broken for e.g. my use case making this unusable.

Thank continue in the next Sprint (next week). Work has started on it, but as of on hold for this Sprint.

[Flamefire]

Ah ok. Then maybe I misunderstood the significance of removing it from P1 as "P1" was described as "mandatory for next release" and no P1 or P2 as "may or may not come".

So will the fix be included in the next release? If not, do you consider taking my PR instead? It allows (at least) me to use the extension again for tests, has tests and is updated to work with the new pytest version (supported after #4098). It does not create conflicts with the upcoming fix as the whole code will be removed/replaced by the new version using a "native parser" (if I may call it like that)