This .NET Core parallel testing sample uses --list-tests and --filter parameters of dotnet test to slice the tests. The tests are run using the NUnit.

This sample has the 100 tests, and slices them to 20 tests in 5 jobs. You can see the pipeline behavior result by clicking the build status badge above.

jobs:
- job: 'ParallelTesting'
  pool:
    name: Hosted Ubuntu 1604
  strategy:
    parallel: 5
  displayName: Run tests in parallel

• Get test name list of all tests by using --list-tests parameter and grep Test_
• create_slicing_filter_condition.sh makes filter condition to slice the tests, and set into $(targetTestsFilter)

  - bash: |
      tests=($(dotnet test . --no-build --list-tests | grep Test_))
      . 'create_slicing_filter_condition.sh' $tests
    displayName: 'Create slicing filter condition'

 - task: DotNetCoreCLI@2
   displayName: Test
   inputs:
     command: test
     projects: '**/*Tests/*Tests.csproj'
     arguments: '--no-build --filter "$(targetTestsFilter)"'

• Speed up testing by running tests in parallel - Azure Pipelines & TFS | Microsoft Docs