Tutorials ADO.NET Core Tutorial
Unit Testing — Complete Guide
Unit Testing — Complete Guide: free step-by-step lesson with examples, common mistakes, and interview tips — part of ADO.NET Core Tutorial on Toolliyo Academy.
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ADO.NET Core Tutorial · Lesson 71 of 100
Unit Testing
Foundations ✓ → SQL & safety ✓ → Production → Projects
Production · 3 — ASP.NET & enterprise · ~10 min · Module 8: Testing and Debugging
What is this?
Unit-test logic against IOrderRepository fakes — no SQL required.
Why should you care?
ShopNest use-case rules should run in milliseconds on CI.
See it live — copy this example
Use a .NET console or API project with SQL Server LocalDB. Run dotnet run after pasting.
var fake = new FakeOrderRepository();
fake.Seed(new OrderDto(1, 10, "Pending"));
var sut = new CancelOrderHandler(fake);
await sut.Handle(1, ct);
Assert.Equal("Cancelled", fake.Get(1)!.Status);What happened?
- Fake in-memory repo.
- Assert domain outcomes.
- Keep SqlClient tests for integration.
Practice next
- Write FakeOrderRepository.
- Test cancel handler.
- CI dotnet test.
- Test not-pending cancel fails.
- Verify fake was called.
Remember
Fakes for units. Fast CI. SQL in integration.
ShopNest handler unit tests
Cancel logic tested with fake repo.
Outcome: CI stays fast and green.
Interview prep for this lesson
Practice these questions aloud after reading—each links to a full structured answer.
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