The secret unit testing tools no one has ever told you about

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

Consultant & software architect
Developing software since 2002
Clean Coder & Test Driven Developer
Pluralsight author
https://www.pluralsight.com/authors/dror-helper
B: http://helpercode.com
T: @dhelper
About.ME

Why should you care about tools?

Background: unit testing tools

[Test]
public void AddItem_AddTwoValidProductsToCart_TotalEqualsItemsPrice()
{
var fakeRepository = A.Fake<IProductRepository>();
Product product1 = new Product(1, "product-1", 100);
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));
}

@Test
public void addItem_addTwoValidProductsToCart_totalEqualsItemsPrice() {
IProductRepository fakeRepository = mock(IProductRepository.class);
when(fakeRepository.getProductById(1)).thenReturn(product1);
when(fakeRepository.getProductById(2)).thenReturn(product2);
ShoppingCart cart = new ShoppingCart(fakeRepository);
cart.AddItem(1);
cart.AddItem(2);
assertEquals(300.0, cart.getTotal(), 0);
}

TEST(ShoppingCartTests, AddProductById_AddTwoProducts_GetTotalPriceReturnSumPrice)
{
FakeRepository fake_repository;
Product product1 = Product(1, "product-1", 100);
Product product2 = Product(2, "product-2", 200);
EXPECT_CALL(fake_repository, GetProductById(1)).WillRepeatedly(Return(product1));
EXPECT_CALL(fake_repository, GetProductById(2)).WillRepeatedly(Return(product2));
ShoppingCart shopping_cart(fake_repository);
shopping_cart.AddProductById(1);
shopping_cart.AddProductById(2);
ASSERT_EQ(300, shopping_cart.GetTotalPrice());
}

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

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

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

Arrange issues
[TestMethod]
public async Task LoadUser_ReputationStaysTheSame_ReputationTrendSame() {
var user1 = 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();
var result = await InvokeAsync(() => ((SolidColorBrush)viewModel.ReputationTrend).Color);
Assert.AreEqual(Colors.White, result);
}

[TestInitialize]
public async Task InitializeViewModel() {
_viewModel = await InvokeAsync(() => new UserDetailsViewModel(fakeUserRepository));
}
[TestMethod]
await _viewModel.LoadUser();
var result = await InvokeAsync(() => ((SolidColorBrush)_viewModel.ReputationTrend).Color);
}
Using Setup/TearDown

[TestInitialize]
public async Task InitializeViewModel() {
_viewModel = await InvokeAsync(() => new UserDetailsViewModel(fakeUserRepository));
}
[TestMethod]
var result = await InvokeAsync(() => ((SolidColorBrush)_viewModel.ReputationTrend).Color);
}
private UserDetailsViewModel _viewModel;

Extract to methods
[TestMethod]
var user1 = CreateUser(10);
var user2 = CreateUser(10);
var viewModel = await InvokeAsync(() => new UserDetailsViewModel(fakeUserRepository));
var result = await InvokeAsync(() => ((SolidColorBrush)viewModel.ReputationTrend).Color);
}

Over abstraction
[TestMethod]
var viewModel = InitializeSystem(10, 10);
await RunTest(2);
CheckColor(Colors.White)
}

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
};
}

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
};
}
}

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();

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

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);
}

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;
result = _UserManager.ChangePasswordAsync(_TestUser.Id, "Password123!", "123456789!").Result;
result = _UserManager.ChangePasswordAsync(_TestUser.Id, "Password123!", "abcdefghijk").Result;
result = _UserManager.ChangePasswordAsync(_TestUser.Id, "Password123!", "abcdefghijK1!").Result;
Assert.IsTrue(result.Succeeded);
}
http://stackoverflow.com/q/26400537/11361

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

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

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…

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}"));
}
}
}
http://blog.drorhelper.com/2011/02/multiple-asserts-done-right.html

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

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

@Test
void dependentAssertions() {
assertAll("properties",
() -> {
String firstName = person.getFirstName();
assertNotNull(firstName);
// Executed only if the previous assertion is valid.
assertAll("first name",
() -> assertTrue(firstName.startsWith("J")),
() -> assertTrue(firstName.endsWith("n")));
},
() -> {
String lastName = person.getLastName();
assertNotNull(lastName);
// Executed only if the previous assertion is valid.
assertAll("last name",
() -> assertTrue(lastName.startsWith("D")),
() -> assertTrue(lastName.endsWith("e")));
});
}

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

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

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

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

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/

Test structure issues
• What to call the test?
• AAA is not mandatory
• What should I test?
• How to avoid unreadable, complicated tests?
- Unit testing framework provide no structure

The BDD approach
Step
Definitions

Specifications == focused test
Feature: Addition
In order to avoid silly mistakes
As a math idiot
I want to be told the sum of two numbers
Scenario: Add two numbers
Given I have entered 50 into the calculator
And I have entered 70 into the calculator
When I press add
Then the result should be 120 on the screen

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

[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

Continuous Testing Tools
DotCover
Typemock
Runner
nCrunch
VS2017
(Enterprise)

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
Infinitest (Java)
Corvlet (.NET Core)

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

The secret unit testing tools no one has ever told you about

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