Create automated functional tests (using SpecFlow) to verify Weevil's software requirements.

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HowTo: Write Gherkin Scenarios

Scenario Titles

There isn't a single "one-size-fits-all" approach to naming Gherkin scenarios, but there are best practices that can make scenarios more understandable and maintainable. These practices aim to make the scenario name descriptive enough to understand its purpose at a glance while being concise enough to be easily digestible. Here are some guidelines:

• Clarity Over Brevity: The name should make it immediately clear what the scenario is testing. While brevity is desired, it should not come at the expense of clarity.
• Domain Language: Use the language that the team and stakeholders understand. Domain-Specific Language (DSL) can be very effective here.
• Outcome-Oriented: Include the expected outcome or behavior in the scenario name to give a clear idea of what success looks like for the test.
• Avoid Implementation Details: Try not to include how the test will achieve its goal but rather focus on what you are trying to achieve.
• Consistency: Stick to a naming convention that the team agrees upon to make it easier to search for and understand scenarios.

Examples following these guidelines might look like:

• "Successful login with valid credentials"

• "Error on empty shopping cart checkout"

• "Admin access denied for regular users"

• "Open log file with valid format"

• "Error on opening corrupted log file"

  Lessons Learned

• Single Quote / Double Quote / Backtick text formatting works for...

  • GitHub : single & double quoted text
  • GitHub codespace: does not support syntax highlighting for Gherkin strings

Relates To

• 362

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• 325

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Troubleshooting: MS Tests Won't Run

Symptoms:

• MS Test automated tests which include SpecFlow + DatenLokator won't start via Visual Studio's Test Explorer.

Implementation Notes:

• If you Debug a test you will discover that MS Test does in fact start. The problem is:
  • You cannot use _MS Test+'s AssemblyInitialize attribute in conjunction with SpecFlow's test run hooks.
• Solution:
  1. Remove _MS Test+'s AssemblyInitialize.
  2. Use SpecFlow's test run hooks to initialize the DatenLokator v2.0.0 library.

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Challenges

STA Thread

The following Gherkin scenario is failing with a run-time error:

[TestMethod]
public async Task OpenAsync()
{
   // InvalidOperationException: The calling thread must be STA, because many UI components require this.
   var window = Substitute.For<Window>(); 
}

With Just My Code disabled, you can see that the error is ultimately due to a .NET guard failing:

Microsoft.VisualStudio.TestPlatform.MSTestAdapter.PlatformServices.Utilities.VSInstallationUtilities.cs:

public static string? VSInstallPath
{   
   // ...
   // Use the Setup API to find the installation folder for currently running VS instance.
   if (new SetupConfiguration() is ISetupConfiguration setupConfiguration)
   {
      var currentConfiguration = setupConfiguration.GetInstanceForCurrentProcess();
      // ...
   } 
}

Next Steps

• Is Weevil really running UI for the MS Test... or is this simply a WPF guard that is being accidentally triggered?
• Solutions:
  1. Avoid triggering the guard
     • Can we create the functional test without creating a Window?
       • The window is only used when displaying About and Dashboard dialogs.
       • Q: Why don't we need a parent Window reference when displaying Open As? <<<
  2. Run the functional test using a STA Thread

Related Articles

• MSTest v2: Customize test execution
  • Talks about STA threads

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Problem: Unexpected SpecFlow Errors

Symptoms

Visual Studio is displaying weird compiler errors & warnings

• AndDiscoveryProviderSucceed: Error during binding discovery
• FileNotFoundException: Could not load file or assembly 'System.Runtime, Version=8.0.0.0
• JsonReaderException: Unexpected character encountered while parsing value
• AndDiscoveryProviderSucceed: The project bindings (e.g. step definitions) could not be discovered. Navigation, step completion and other features are disabled.

In Visual Studio:

• Gherkin statements that clearly did not exist... were not being displayed as purple text in Visual Studio.

Root Cause

• This problem appeared after upgrading projects to .Net Core 8

Solution

• Install the Visual Studio SpecFlow extension for .Net Core 8