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Forms also have a collection of controls (Controls property) that you can loop through. This is useful for when you want to do something to multiple controls and don’t want to have to manually type out code to deal with individual controls. Here’s an example of looping through a form’s top-level controls: Note: In the … Read more
When you use HttpClient to make requests, you can directly get the status code from the HttpResponseMessage object, like this: The main reason for checking the status code is to determine if the request was successful and then reacting to error status codes (usually by throwing an exception). The HttpResponseMessage class has two helpers that … Read more
You can unit test a validation attribute by creating an instance of it and then testing the two methods: In this article, I’ll show examples of unit testing these methods in a custom validation attribute and in a built-in validation attribute (i.e. [Range]). Unit testing a custom validation attribute Consider the following custom validation attribute … Read more
There are many built-in model validation attributes available – such as [Required] and [Range] – which you can use to handle most validation scenarios. When these aren’t sufficient, you can create a custom validation attribute with your own validation logic. I’ll show an example of how to do that. 1 – Subclass ValidationAttribute and implement … Read more
The simplest way to implement GetHashCode() is to use the built-in System.HashCode.Combine() method and pick the properties you want to include. Let it do the work for you. Furthermore, the simplest way to implement Equals() is to use the is operator and compare all the properties. Here’s an example: Note: Use (Title, Year).GetHashCode() in versions … Read more
When you need to verify that the code under test called a method with the expected parameters, you can mock the method with Moq and use Verify() + It.Is<T>() to check the parameters passed in. Verify() asserts that the method call happened as expected with the specified parameters. Here’s an example. This is verifying that … Read more
You can use the is operator to check if an object is a certain type. Here’s an example: You can also use the is operator to declare a variable of the target type, like this: Note: The employee object is only available in the if block, but IntelliSense shows it out of its scope. If … Read more
The key to unit testing an ApiController class is to mock out all of its dependencies, including the controller’s HttpContext property, like this: If the controller method you’re testing uses anything from the HttpContext, then you’ll want to swap in your own value. Otherwise HttpContext will be null and you’ll get a NullReferenceException. Fortunately Microsoft … Read more
I’ll show examples of using the pattern matching operators – ‘not’, ‘and’, ‘or‘ – with the is operator. These are nice syntax sugar that make conditional logic a bit easier to read. Note: ‘not’, ‘and’, ‘or’ were added in C# 9. ‘not’ operator Here’s an example of the not operator: This is checking if the … Read more
When you have code that calls an endpoint, you need to make sure it’s resilient and can handle error scenarios, such as timeouts. One way to prove your code is resilient is by using toxiproxy to simulate bad behavior. Toxiproxy sits between your client code and the endpoint. It receives requests from your client, applies … Read more