Unit Testing for C# Developers

In black-box testing for the max method, identify three execution paths: a greater, b greater, and equal, and write tests based on input scenarios rather than implementation.

Learn to temporarily disable a test with NUnit's Ignore attribute, preserving a reason message, so you can focus on other work without deleting or commenting out tests.

Avoid extremes on testing; maintain an essential automated test suite to catch bugs early, because the cost of late fixes outweighs upfront testing, with the double-entry bookkeeping analogy.

Explore the fundamentals of unit testing, building small, isolated tests with a single responsibility that verify outcomes, not implementation, and use setup and parameterized tests for reliability.

Explore how code coverage reveals untested lines, compare DotCover with Visual Studio Enterprise Edition and ReSharper Ultimate, and learn to test all execution paths using black-box thinking.

Learn to implement and refactor unit tests for a DemeritPointsCalculator, using parameterized test cases, exception handling for out-of-range speeds, and a MaxSpeed constant.

Refactor legacy code into a testable, loosely coupled design by extracting resource logic into a class and using an interface as a contract; inject dependencies from outside, enabling test doubles.

Learn to refactor legacy code into a loosely coupled, testable design by extracting file access into a FileReader, creating an IFileReader interface, and using a fake implementation for unit tests.

Create mock objects with the Moq library to test external dependencies, configure IFileReader behavior, and inject mock.Object into your video service.

Use mocks sparingly to remove external resources from tests. Avoid sprawling interfaces and bloated constructors, and keep tests fast and reliable by focusing on external behavior rather than implementation.

Refactor by extracting database access into a video repository to isolate external resources, then inject an IVideoRepository interface into VideoService for testable, loosely coupled unit testing.

Learn to unit test the GetUnprocessedVideos method with mocks, cover empty and multiple videos, and consider repository dependencies and constructor design to keep tests focused.

Practice unit testing the InstallerHelper class by examining its DownloadInstaller method, which uses WebClient to download a file from a constructed URL and returns true or false.

Develop unit tests for the OverlappingBookingsExist booking overlap check in BookingHelper, refactoring for loose coupling and testability while validating cancellations, querying non-cancelled bookings, and returning the first overlap reference.

Develop comprehensive unit tests for overlapping bookings in C# by defining all test cases—before, in middle, after overlaps, and cancellation scenarios—and organize tests in a BookingHelperTests class with mocking.

Unit testing for C# developers guides fixing a bug in booking overlap logic by using a proven two-date overlap condition and expanding tests to validate all scenarios.

Explore unit testing for C# by writing tests for SendStatementEmails, isolate external resources, and apply dependency injection to inject SaveStatement and EmailFile dependencies.

Learn to write the first interaction test for a C# application service by mocking the unit of work and collaborators, and verifying statement generation and email sending for housekeepers.

Keep tests clean by introducing a setUp method, promoting shared objects to private fields, and reducing duplication so each test starts with fresh unit of work and mocks.

Master c# unit testing with mocks and setup to verify email sending of the statement when a valid file name is returned, and prevent sending for null or empty names.