HttpTriggerTester Expression Tree Limitations

[m-flak]

HttpTriggerTester Expression Tree Limitations

Background

In my tests project, I have created an extension method using reflection to automatically get the route of my HTTP-Triggered-Functions with that method. The goal here was to eliminate requirements for test code updates after changes to a Function's route in the main code. It almost works.

I've since written my code around this limitation, but it requires me to spin up & run an entire HostTesterBase implementor twice. 😰

Issue

HttpTriggerTester's Run/RunAsync methods, unlike TypeTester's, uses expression trees. SRC

public async Task<ActionResultAssertor> RunAsync(Expression<Func<TFunction, Task<IActionResult>>> expression)

This means that I am unable to write something like this without experiencing compilation errors:

        var sut = await test
            .HttpTrigger<QueueTaskCreateFunction>()
            .RunAsync(f => f.Run(test.CreateHttpRequest(HttpMethod.Post, f.GetFunctionRoute(), contentType: MediaTypeNames.Text.Plain), context.Object));

A statement like this would work with TypeTester, but I can't use TypeTester to test my HTTP-Triggered-Function.

Is there a technical reason for HttpTriggerTester's Run/RunAsync methods not having an overload for Action<T> or Func<T1,T2>??

Workaround

The following boilerplate accomplishes what I intended without any issues:

       var route = test
            .Type<QueueTaskCreateFunction>()
            .Run(f => f.GetFunctionRoute())
            .Result;

        var request = test
            .CreateHttpRequest(HttpMethod.Post, route, contentType: MediaTypeNames.Text.Plain);

        var sut = await test
            .HttpTrigger<QueueTaskCreateFunction>()
            .RunAsync(f => f.Run(request, context.Object));