A dive into dependency injection in traditional .Net applications and ASP.Net Core. Followed by how dependency injection enables unit testing in .Net core and EF core. Code examples of how to unit test at the controller, service, and data layers.
Inversion of Control (IoC) • Interface Segregation • Functional Programming • Hard to Test code • It is tightly coupled to the concrete implementation. • It violates the Single Responsibility Principle. • It lies about its dependencies. • It is hard to understand and maintain.
Ex: if you have two libraries: foo.dll, bar.dll • have 2 unit test assemblies: foo.tests.dll, bar.tests.dll Try to have at least 1 test class per class • Ex: if you have two classes in project foo: a.cs, b.cs • have 2 unit test classes in project foo.tests: aTests.cs, bTests.cs • If there are a lot of methods, or tests for some methods, split it up if there are a too many tests in one class. Use folders to mirror layout and namespaces of target project
under test • Foo.cs -> FooTests.cs [UnitOfWork_StateUnderTest_ExpectedBehavior] Examples • public void GetLines_twoLineString_returnsTwoStrings() • public void GetNonWhitespaceLines_null_Throws() • public void ReplaceMultiple_stringWithHashNonMatchingMappings_String() • public void ReplaceMultiple_stringMatchingMappings_UpdatedString()