C# – Examples of using GroupBy() (Linq)

Here’s an example of using the Linq GroupBy() method to group coders by language: This example outputs the following: GroupBy() produces groups that contain the grouping key (i.e. Language) and the list of objects in the group (i.e. the Coder objects). The GroupBy() syntax is complex because it supports many scenarios. You can select one … Read more

C# – How to match an anonymous type parameter in a mocked method

When an anonymous type is defined in one assembly, it won’t match an anonymous type defined in another assembly. This causes problems when you’re unit testing and trying to mock a method that has an anonymous type parameter. For example, let’s say you’re trying to unit test the following method: To unit test this, you … Read more

C# – Serialize anonymous types with System.Text.Json

It’s common to need to customize serialization. When you need to do this, you’d typically need to create a custom JSON converter and pass it in during serialization. Depending on your scenario, an alternative approach is to use anonymous types, like this: Basically you select properties from another object and format them as desired, and … Read more

C# – How to unit test code that uses Dapper

Dapper makes your code difficult to unit test. The problem is that Dapper uses static extension methods, and static methods are difficult to mock out. One approach is to wrap the Dapper static methods in a class, extract out an interface for that wrapper class, and then dependency inject the wrapper interface. In the unit … Read more