[Failing test] TFS2018 task.setvariable issue with isOutput

[michal-ciechan]

Hey, we are still using an on prem TFS 2018 and latest code which outputs 2 sets of set parameters breaks because of the isOutput=true. We get the following error.

Output variable value cannot be null

This causes the task to fail.

Currently worked around it with a flag [AzurePipelinesSetParamSkipIsOutput] in a custom version of GitVersion. (Will raise another Issue as to why).

Happy to do the work for whatever flag/method of allowing user to skip the isOutput=true message.

IMHO I think it should be a flag we can pass rather than a ENV variable we set. (Setting custom env vars would need a separate build step in the build pipeline, where as a flag can be easily added to the existing build step)

I have checked our Env variables and unfortunately I could not find any Build Server / TFS version other than Build Agent Version, but not sure which versions it affects.

Test code

See Code michal-ciechan/GitVersion at feature/TFS2019-output-vars-issue.

[Test]
public void GenerateSetParametersShouldNotAddIsOutputIfSkipFlagIsSet()
{
    //TODO: Set Flag (TBD)
    var vsVersion = buildServer.GenerateSetParameterMessage("Foo", "Bar");

    vsVersion.ShouldContain("##vso[task.setvariable variable=GitVersion.Foo]Bar");
    vsVersion.ShouldNotContain(x =>x.Contains("isOutput", StringComparison.OrdinalIgnoreCase));
}

[michal-ciechan]

Could change the assert to be

vsVersion.Single().ShouldNotContain("isOutput");

Whichever you prefer.