CODEWITHSUNDEEP
c#mvvmasync-awaitmstest
Blingers
Blingers

Reputation: 883

I have a c# mstest unit test that runs fine locally, but fails on the build server. How can I get it to work on build server? (It uses async method)

I have the following unit test which runs fine locally (simplified and anonymised):

[TestMethod]
public void GotoPageCommand_Calls_PCCollection_SearchPage()
{
  var page = 100;
  var sut = CreateSut();
  sut.SearchPage = page;
  sut.GotoPageCommand.Execute(null);

  _tableViewModel.Verify(s => s.SearchPage(page), Times.Once());
}

The problem is the last line shows 0 times on the build server, but correctly shows 1 time when run locally (either on it's own or when running all tests).

The problem is obviously something to do with the async method.

This is a simplified version of the method being tested (the GotoPageCommand, which should then call the SearchPage method):

in the viewmodel:

public ICommand GotoPageCommand { get; }

. . .
// in the ctor:
GotoPageCommand = new DelegatingCommand(GotoPage, CanGotoPage);

. . .
// the GotoPage method

private async void GotoPage()
{
  // lots of stuff...
  try
  {
    await Task.Run(() =>
    {
      // This is the problem line that correctly verifies as being
      // called once when run locally, but shows zero times when 
      // run on build server.
      _pcCollection.PagData.SearchPage(page); 
    });
  }

Upvotes: 0

Views: 46

Answers (1)

Ivan Petrov
Ivan Petrov

Reputation: 4465

I think xUnit has support for testing async-void, but if you cannot switch testing frameworks - there is an implementation that I wrote in another answer (check the others answers too) that would allow you to test ICommand.Execute. For it to work, you'd need to make DelegatingCommand's Execute method async void though.

Or you can do something very bad and add Thread.Sleep(20) before the Verify to simulate await and work-around the race condition you have now.

Upvotes: 0

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