Unit testing failed in python3.

[zhouwangyang]

Visual Studio Code - Insiders: 1.32.0-insider
python-insider: 2019.2.5135-alpha
python version: Python 3.7.2 64bit
Repro steps:
1.Git clone https://github.com/qubitron/pydemo
2.Open Anaconda Prompt window
3.Cd pydemo
4.Run py -3 setup.py
5.Open hello-stackoverflow folder inVSC
6.Change environment to Python 3.7.2 in Status bar
7.Select "Test"

8.Click "Run All Unit Tests",Make sure a prompt is popup
9.Click "Enable and configure a Test Framework"
10.From the menus select "Unittest framework->Tests folder->Test_*.py" file
11.Click "Run All Unit Tests" button
Except result: Test code lenses should appear and test count i status bar like below

Actual result: no code lenses, wrong test count in status bar.

note:it worked OK when changed environment to Anaconda

[karrtikr]

Closing in favour of #2644