List of Listings

Chapter 1. The goal of unit testing

Listing 1.1. A sample method partially covered by a test

Listing 1.2. Version of IsStringLong that records the last result

Listing 1.3. A test with no assertions always passes.

Chapter 2. What is a unit test?

Listing 2.1. Tests written using the classical style of unit testing

Listing 2.2. Tests written using the London style of unit testing

Chapter 3. The anatomy of a unit test

Listing 3.1. A test covering the Sum method in calculator

Listing 3.2. A single-line act section

Listing 3.3. A two-line act section

Listing 3.4. Differentiating the SUT from its dependencies

Listing 3.5. Calculator with sections separated by empty lines

Listing 3.6. Arrangement and teardown logic, shared by all tests

Listing 3.7. Extracting the initialization code into the test constructor

Listing 3.8. Extracting the common initialization code into private factory methods

Listing 3.9. Common initialization code in a base class

Listing 3.10. A test named using the rigid naming policy

Listing 3.11. A test that encompasses several facts

Listing 3.12. Two tests verifying the positive and negative scenarios

Listing 3.13. Generating complex data for the parameterized test

Chapter 4. The four pillars of a good unit test

Listing 4.1. Generating an HTML representation of a message

Listing 4.2. Verifying that MessageRenderer has the correct structure

Listing 4.3. Verifying the source code of the MessageRenderer class

Listing 4.4. Verifying the outcome that MessageRenderer produces

Listing 4.5. Trivial test covering a simple piece of code

Listing 4.6. Test verifying which SQL statement is executed

Chapter 5. Mocks and test fragility

Listing 5.1. Using the Mock class from a mocking library to create a mock

Listing 5.2. Using the Mock class to create a stub

Listing 5.3. Asserting an interaction with a stub

Listing 5.4. storeMock: both a mock and a stub

Listing 5.5. User class with leaking implementation details

Listing 5.6. A version of User with a well-designed API

Listing 5.7. State as an implementation detail

Listing 5.8. A domain class with an application service

Listing 5.9. Connecting the domain model with external applications

Listing 5.10. Mocking that doesn’t lead to fragile tests

Listing 5.11. Mocking that leads to fragile tests

Chapter 6. Styles of unit testing

Listing 6.1. Output-based testing

Listing 6.2. State-based testing

Listing 6.3. Communication-based testing

Listing 6.4. State verification that takes up a lot of space

Listing 6.5. Using helper methods in assertions

Listing 6.6. Comment compared by value

Listing 6.7. Modification of an internal state

Listing 6.8. Initial implementation of the audit system

Listing 6.9. Injecting the filesystem explicitly via the constructor

Listing 6.10. Using the new IFileSystem interface

Listing 6.11. Checking the audit system’s behavior using a mock

Listing 6.12. The AuditManager class after refactoring

Listing 6.13. The mutable shell acting on AuditManager’s decision

Listing 6.14. Gluing together the functional core and mutable shell

Listing 6.15. The test without mocks

Chapter 7. Refactoring toward valuable unit tests

Listing 7.1. Initial implementation of the CRM system

Listing 7.2. Application service, version 1

Listing 7.3. User factory

Listing 7.4. The new class in the domain layer

Listing 7.5. Controller after refactoring

Listing 7.6. User after refactoring

Listing 7.7. User with a new property

Listing 7.8. The controller, still stripped of all decision-making

Listing 7.9. Controller deciding whether to change the user’s email

Listing 7.10. Changing an email using the CanExecute/Execute pattern

Listing 7.11. Sends a notification even when the email has not changed

Listing 7.12. User adding an event when the email changes

Listing 7.13. The controller processing domain events

Listing 7.14. Testing the creation of a domain event

Chapter 8. Why integration testing?

Listing 8.1. The user controller

Listing 8.2. The integration test

Listing 8.3. An example of logging in User

Listing 8.4. Extracting support logging into the DomainLogger class

Listing 8.5. DomainLogger as a wrapper on top of ILogger

Listing 8.6. Replacing DomainLogger in User with a domain event

Listing 8.7. Latest version of UserController

Listing 8.8. Storing ILogger in a static field

Listing 8.9. Injecting the logger explicitly

Chapter 9. Mocking best practices

Listing 9.1. User controller

Listing 9.2. Event dispatcher

Listing 9.3. Integration test

Listing 9.4. Message bus

Listing 9.5. Integration test targeting IBus

Listing 9.6. A spy (also known as a handwritten mock)

Listing 9.7. Using the spy from listing 6.43

Listing 9.8. Mock assertions

Chapter 10. Testing the database

Listing 10.1. Class that enables access to the database

Listing 10.2. User controller

Listing 10.3. User controller, repositories, and a transaction

Listing 10.4. User controller with Entity Framework

Listing 10.5. Integration test reusing CrmContext

Listing 10.6. Base class for integration tests

Listing 10.7. Integration test with three database contexts

Listing 10.8. A separate method that creates a user

Listing 10.9. Adding default values to the factory

Listing 10.10. Using the factory method

Listing 10.11. Decorator method

Listing 10.12. Data assertions after extracting the querying logic

Listing 10.13. Fluent interface for data assertions

Listing 10.14. Integration test after moving all technicalities out of it

Chapter 11. Unit testing anti-patterns

Listing 11.1. A class with a complex private method

Listing 11.2. Extracting the complex private method

Listing 11.3. A class with a private constructor

Listing 11.4. A class with private state

Listing 11.5. Leaking algorithm implementation

Listing 11.6. A parameterized version of the same test

Listing 11.7. Test with no domain knowledge

Listing 11.8. Logger with a Boolean switch

Listing 11.9. A test using the Boolean switch

Listing 11.10. A version without the switch

Listing 11.11. A class that calculates statistics

Listing 11.12. A controller using StatisticsCalculator

Listing 11.13. Test that mocks the concrete class

Listing 11.14. Splitting StatisticsCalculator into two classes

Listing 11.15. Controller after the refactoring

Listing 11.16. Current date and time as an ambient context

Listing 11.17. Current date and time as an explicit dependency