This document discusses various unit testing tools and practices, emphasizing the significance of writing clear and maintainable tests. It highlights the importance of patterns like the builder pattern and the use of automocking containers to facilitate testing. Additionally, it reviews best practices for assertions and encourages the use of continuous testing tools to improve test quality.

1. The secret
Unit Testing tools
no one has ever told you about
Dror Helper | http://helpercode.com | @dhelper

2. Consultant & software architect
Developing software since 2002
Clean Coder & Test Driven Developer
Pluralsight author
B: http://helpercode.com
T: @dhelper
About.ME

3. Background: unit testing tools

4. [Test]
public void AddItem_AddTwoValidProductsToCart_TotalEqualsItemsPrice()
{
var fakeRepository = A.Fake<IProductRepository>();
Product product1 = new Product(1, "product-1", 100);
Product product2 = new Product(2, "product-2", 200);
A.CallTo(() => fakeRepository.GetProductById(1)).Returns(product1));
A.CallTo(() => fakeRepository.GetProductById(2)).Returns(product2));
var shoppingCart = new ShoppingCart(fakeRepository);
shoppingCart.AddItem(1);
shoppingCart.AddItem(2);
Assert.That(shoppingCart.Total, Is.EqualTo(300));
}

5. (Most)
Unit Testing
Frameworks
[Test]
public void MyTest()
{
}

6. A good Unit Test should be:
Easy
to write
Simple
to read
Trivial
to maintain

7. What about AAA?
[Test]
public async void GetUserFromUrl() {
var clientFake = A.Fake<IJsonClient>();
A.CallTo(() => clientFake.HttpGetUncompressedAsync(A<string>.Ignored))
.Returns(Task.FromResult(JsonResult));
var userRepository = new UserRepository(clientFake);
var user = await userRepository.GetUser(11361);
var expected = new User {
Id=11361, DisplayName = "Dror Helper", ImageUrl=DefaultAvatar, Reputation=13904
};
Assert.That(user, Is.EqualTo(expected));
}
Arrange
 Act
 Assert

8. Test setup (Arrange)

9. Arrange issues
[TestMethod]
public async Task LoadUser_ReputationStaysTheSame_ReputationTrendSame() {
var user1 = new User {ImageUrl = "http://dummy.jpg", Reputation = 10};
var user2 = new User {ImageUrl = "http://dummy.jpg", Reputation = 10};
var fakeUserRepository = new FakeUserRepository(new[] { user1, user2 });
var viewModel = await InvokeAsync(() => new UserDetailsViewModel(fakeUserRepository));
await viewModel.LoadUser();
await viewModel.LoadUser();
var result = await InvokeAsync(() => ((SolidColorBrush)viewModel.ReputationTrend).Color);
Assert.AreEqual(Colors.White, result);
}

10. [TestInitialize]
public async Task InitializeViewModel() {
var user1 = new User {ImageUrl = "http://dummy.jpg", Reputation = 10};
var user2 = new User {ImageUrl = "http://dummy.jpg", Reputation = 10};
var fakeUserRepository = new FakeUserRepository(new[] { user1, user2 });
_viewModel = await InvokeAsync(() => new UserDetailsViewModel(fakeUserRepository));
}
[TestMethod]
public async Task LoadUser_ReputationStaysTheSame_ReputationTrendSame() {
await _viewModel.LoadUser();
await _viewModel.LoadUser();
var result = await InvokeAsync(() => ((SolidColorBrush)_viewModel.ReputationTrend).Color);
Assert.AreEqual(Colors.White, result);
}
Using Setup/TearDown

11. [TestInitialize]
public async Task InitializeViewModel() {
var user1 = new User {ImageUrl = "http://dummy.jpg", Reputation = 10};
var user2 = new User {ImageUrl = "http://dummy.jpg", Reputation = 10};
var fakeUserRepository = new FakeUserRepository(new[] { user1, user2 });
_viewModel = await InvokeAsync(() => new UserDetailsViewModel(fakeUserRepository));
}
[TestMethod]
public async Task LoadUser_ReputationStaysTheSame_ReputationTrendSame() {
await _viewModel.LoadUser();
await _viewModel.LoadUser();
var result = await InvokeAsync(() => ((SolidColorBrush)_viewModel.ReputationTrend).Color);
Assert.AreEqual(Colors.White, result);
}
private UserDetailsViewModel _viewModel;

12. Abusing Setup
methods

13. Extract to methods
[TestMethod]
public async Task LoadUser_ReputationStaysTheSame_ReputationTrendSame() {
var user1 = CreateUser(10);
var user2 = CreateUser(10);
var fakeUserRepository = new FakeUserRepository(new[] { user1, user2 });
var viewModel = await InvokeAsync(() => new UserDetailsViewModel(fakeUserRepository));
await viewModel.LoadUser();
await viewModel.LoadUser();
var result = await InvokeAsync(() => ((SolidColorBrush)viewModel.ReputationTrend).Color);
Assert.AreEqual(Colors.White, result);
}

14. The problem with Factories
private User CreateUser(int reputation) {
return new User
{
ImageUrl = "http://dummy.jpg",
Reputation = reputation
};
}
private User CreateUser(int reputation, string imageUrl) {
return new User
{
ImageUrl = imageUrl,
Reputation = reputation
};
}

15. Solution: Builder Pattern
class UserBuilder {
private int _id, _reputation;
private string _name, _imageUrl;
public UserBuilder() {
_id = 1;
_name = "dummy";
_imageUrl = "http://dummy.jpg";
}
User Build() {
return new User {
Id = _id, Name = _name, ImageUrl = _imageUrl, Reputation = _reputation
};
}
}

16. Builder Pattern (cont)
class UserBuilder {
...
public UserBuilder WithName(string name) {
_name = name
return this;
}
public UserBuilder WithReputation(int reputation) {
_reputation = reputation
return this;
}
...
}
var user1 = new UserBuilder()
.WithReputation(10)
.Build();

17. Tool: AutoMocking Containers
Test Container SUT
http://blog.ploeh.dk/2013/03/11/auto-mocking-container/
New()
Configure
CreateCreate SUT
Act

18. Verification (Assert)

19. Can you spot the problem?
[TestMethod]
public void PerformSomeActionReturns42()
{
var myClass = ...
bool initOk = myClass.Initialize();
var result = myClass.PerformSomeAction();
Assert.IsTrue(initOk);
Assert.AreEqual(42, result);
}

20. How about now?
[TestMethod]
public void TestPasswordComplexity()
{
var result = _UserManager.ChangePasswordAsync(_TestUser.Id, "Password123!", "1!").Result;
Assert.IsFalse(result.Succeeded);
result = _UserManager.ChangePasswordAsync(_TestUser.Id, "Password123!", "123456789").Result;
Assert.IsFalse(result.Succeeded);
result = _UserManager.ChangePasswordAsync(_TestUser.Id, "Password123!", "123456789!").Result;
Assert.IsFalse(result.Succeeded);
result = _UserManager.ChangePasswordAsync(_TestUser.Id, "Password123!", "abcdefghijk").Result;
Assert.IsFalse(result.Succeeded);
result = _UserManager.ChangePasswordAsync(_TestUser.Id, "Password123!", "abcdefghijK1!").Result;
Assert.IsTrue(result.Succeeded);
}
http://stackoverflow.com/q/26400537/11361

21. How many Asserts per test?
One Assert per test
2 Asserts == 2 Tests
Really???

22. Multiple Asserts can make sense
[TestMethod]
public void CompareTwoAsserts()
{
var actual = GetNextMessage();
Assert.AreEqual(1, actual.Id);
Assert.AreEqual("str-1", actual.Content);
}

23. HOW UNIT TESTING FRAMEWORKS HURT YOUR UNIT TESTING EFFORTS
WHY TESTS THROW EXCEPTIONS ON FAILURE?
It’s trivial, and best practice
Helps Decouple test runner from test
But not necessary…

24. public class AssertAll
{
public static void Execute(params Action[] assertionsToRun)
{
var errorMessages = new List<exception>();
foreach (var action in assertionsToRun)
{
try
{
action.Invoke();
}
catch (Exception exc)
{
errorMessages.Add(exc);
}
}
if(errorMessages.Any())
{
string errorMessage = string.Join("n", errorMessages);
Assert.Fail($"The following conditions failed:n{errorMessage}"));
}
}
}
https://helpercode.com/2011/02/16/multiple-asserts-done-right/

25. Using Assert.All
[TestMethod]
public void CompareTwoAsserts()
{
var actual = CreateMessage();
AssertAll.Execute(
() => Assert.AreEqual(1, actual.Id),
() => Assert.AreEqual("str-1", actual.Content);
}

26. Some frameworks are catching up!
https://github.com/nunit/docs/wiki/Multiple-Asserts

27. Assert.AreEqual(5, 2 + 2); Assert.AreEqual(2 + 2, 5)

28. Assert.AreEqual(5, 2 + 2); Assert.IsTrue(2 + 2 == 5)

29. How to choose the right Assert?
• IsTrue vs. AreEqual
• Parameter ordering confusion
• StringAssert/CollectionAssert
It’s all about proper error messages

30. AssertHelper
[Test]
public void CompareTest()
{
var myClass = new MyClass();
Expect.That(() => myClass.ReturnFive() == 10);
}
[Test]
public void CompareTest()
{
var c1 = new[] { 1, 2, 3, 4, 5 }
Expect.That(() => c1.Contains(42);
}
https://github.com/dhelper/AssertHelper

31. Assertion Libraries: FluentAssertions
[Fact]
public void CompareTwoObjects()
{
var customer1 = new Customer("cust-1", "John Doe");
var customer2 = new Customer("cust-2", "John Doe");
customer1.ShouldBeEquivalentTo(customer2,
o => o.Excluding(customer => customer.Id));
}
http://www.fluentassertions.com/

32. Test organization

33. Test structure issues
• What to call the test?
• AAA is not mandatory
• What should I test?
• How to avoid unreadable, complicated tests?
- Unit testing frameworks do not provide structure

34. The BDD approach
Step
Definitions

35. BDD Example: SpecFlow
http://www.specflow.org/

36. [TestClass]
public class CardHasBeenDisabled {
private Card _card;
private Atm _subject;
void GivenTheCardIsDisabled() {
_card = new Card(false, 100);
_subject = new Atm(100);
}
void WhenTheAccountHolderRequestsMoney() {
_subject.RequestMoney(_card, 20);
}
void ThenTheAtmShouldRetainTheCard() {
Assert.IsTrue(_subject.CardIsRetained);
}
void AndTheAtmShouldSayTheCardHasBeenRetained() {
Assert.AreEqual(DisplayMessage.CardIsRetained, _subject.Message);
}
[TestMethod]
public void Execute()
{
this.BDDfy();
}
}
Tool: BDDfy

37. Test execution

38. Continuous Testing Tools
DotCover
Typemock
Runner
nCrunch
Live Unit Tests

39. The right tools will help you write good tests
Arrange
Builder
Pattern
AutoMocking
Containers
Assert
Multiple
Asserts
3rd party
Assertion
libraries
Test
Structure
“Classic” BDD
In-Code BDD
Continuous
Testing
Typemock Runner
DotCover
nCrunch
Live Unit Testing
Corvlet (.NET Core)

40. Thank you
@dhelper | http://helpercode.com