Secret unit testing tools

The secret unit testing tools no one has
ever told you about
Dror Helper | blog.drorhelper.com | @dhelper
Join the conversation on Twitter: @DevWeek // #DW2016 // #DevWeek

About.ME
Consultant @CodeValue
Developing software (professionally) since 2002
Mocking code since 2008
Clean coder & Test Driven Developer
OzCode (a.k.a “Magical debugging”) Evangelist
Blogger: http://blog.drorhelper.com

But it was not always like that
1st Attempt Failed!
2nd Attempt Failed!!!
New job +
UT + Mentor
Success

Why should I care about tools?

Background: unit testing tools

Well known unit testing tools
Build Failed!

Server
Dev Machine
Source ControlBuild Server
Test Runner
Code
Coverage
Build Agent
Unit Testing
Framework
Isolation
Framework
?

xUnit test framework
Test Suite
Fixture
Test Case
Test Case
Test Case
Test Case
Test Case
Fixture
Test Case
Test Case
Fixture
Test Case
Test Case
Test Case
public class BeforeAndAfter {
[SetUp]
public void Initialize() {
}
[TearDown]
public void Cleanup() {
}
[Test]
public void test1() {
}
[Test]
public void test2() {
}
}

Mocking Frameworks
Unit test
Code under test
DependencyFake object(s)

What Mocking framework can do for you?
• Create Fake objects
• Set behavior on fake objects
• Verify method was called
• And more...

[Test]
public void Calculate_ReturnTwoValidNumbers_ServerCalled()
{
IDataAccess fakeDataAccess = A.Fake<IDataAccess>();
A.CallTo(() => fakeDataAccess.GetData(A<string>.Ignored))
.Returns(new Tuple<int, int>(2, 3));
var fakeCalculatorService = A.Fake<ICalculatorService>();
var cut = new DistrobutedCalculator(fakeDataAccess, fakeCalculatorService);
cut.Calculate();
A.CallTo(() => fakeCalculatorService.Add(2,3)).MustHaveHappened();
}

These tools do not help us write good
unit tests
In fact, sometimes
they prevent us from
writing good unit tests!

Definition: unit tests
Automated piece of code that invokes
a unit of work in the system and then
checks a single assumption about the
behavior of that unit of work
[Roy Osherove, The Art Of Unit Testing]

Unit test structure
[Test]
public void MyTest()
{
}

No guidance  Fragile tests  Stop unit testing

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

Problem solved? Hardly!
• Where to start?
• How to test existing code?
• What about test structure?
• Integration tests vs. unit tests
• What is a “unit of work”?

Test setup (Arrange)

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();
var result = await InvokeAsync(() => ((SolidColorBrush)viewModel.ReputationTrend).Color);
Assert.AreEqual(Colors.White, result);
}

Solution: Setup/TearDown
private UserDetailsViewModel _viewModel;
[TestInitialize]
public async Task InitilizeUserViewModel() {
var user1 = new User { ImageUrl = "http://dummy.jpg", Reputation = 10 };
_viewModel = await InvokeAsync(() => new UserDetailsViewModel(fakeUserRepository));
}
[TestMethod]
await _viewModel.LoadUser();
var result = InvokeAsync(() => ((SolidColorBrush)_viewModel.ReputationTrend).Color);
}

Why you shouldn’t use Setup in unit tests
private UserDetailsViewModel _viewModel;
[TestInitialize]
public async Task InitilizeUserViewModel() {
_viewModel = await InvokeAsync(() => new UserDetailsViewModel(fakeUserRepository));
}
[TestMethod]
var result = InvokeAsync(() => ((SolidColorBrush)_viewModel.ReputationTrend).Color);
}

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

Over extraction
[TestMethod]
public async Task LoadUser_ReputationStaysTheSame() {
var viewModel = InitializeSystem(10, 10);
CheckColor(Colors.White, viewModel);
}

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
};
}

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

Builder pattern (cont.)
class UserBuilder
{
...
public UserBuilder WithName(string displayName) {
_displayName = displayName;
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-container/
New()
Configure
CreateCreate SUT
Act

Automocking with AutoFixture
[Fact]
public void YellIfTouchHotIron() {
var fixture = new Fixture().Customize(new AutoFakeItEasyCustomization());
Fake<IMouth> fakeMouth = fixture.Freeze<Fake<IMouth>>();
Fake<IHand> fakeHand = fixture.Freeze<Fake<IHand>>();
A.CallTo(() => fakeHand.FakedObject.TouchIron(A<Iron>._)).Throws<BurnException>();
var brain = fixture.Create<Brain>();
brain.TouchIron(new Iron {IsHot = true});
A.CallTo(() => fakeMouth.FakedObject.Yell()).MustHaveHappened();
}

Automocking with Typemock Isolator
[TestMethod]
public void FakeAllDependencies_ChangeBehavior()
{
var real = Isolate.Fake.Dependencies<ClassUnderTest>();
var fake = Isolate.GetFake<Dependency>(real);
Isolate.WhenCalled(() => fake.Multiplier).WillReturn(2);
var result = real.Calculate(1, 2);
Assert.AreEqual(6, result);
}

Problem: Complex inputs
• Big objects
• Deep objects
• Need for precision
• Lack of knowledge

Solution: use trivial inputs
Sometimes missing the point
Not always enough for “real test”

Solution: Serialization
Supported in most programming languages (XML, json).
• Need development  testing delayed
• Production code change  indefinitely delayed

Tool: Export using OzCode

Verification (Assert)

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);
}
http://stackoverflow.com/q/26400537/11361

Can you spot the problem?
[TestMethod]
public void TestPasswordComplexity()
{
var result = _UserManager.ChangePasswordAsync(_TestUser.Id, "Password123!", "1!").Result; //Changes the password.
Assert.IsFalse(result.Succeeded);
result = _UserManager.ChangePasswordAsync(_TestUser.Id, "Password123!", "123456789").Result; //Changes the password.
result = _UserManager.ChangePasswordAsync(_TestUser.Id, "Password123!", "123456789!").Result; //Changes the password.
result = _UserManager.ChangePasswordAsync(_TestUser.Id, "Password123!", "abcdefghijk").Result; //Changes the password.
result = _UserManager.ChangePasswordAsync(_TestUser.Id, "Password123!", "abcdefghijK1!").Result; //Changes the password.
Assert.IsTrue(result.Succeeded);
}
http://stackoverflow.com/q/26400537/11361

How many Assert(s) per test?
One Assert Per Test!
Two Assert == Two Tests  Usually ???
”(…the Code is more)
what you'd call guidelines
than actual rules”

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

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())
{
var separator = string.Format("{0}{0}", Environment.NewLine);
string errorMessage = string.Join(separator, errorMessages);
Assert.Fail(string.Format("The following conditions failed:{0}{1}", Environment.NewLine, errorMessage));
}
}
}
http://blog.drorhelper.com/2011/02/multiple-asserts-done-right.html

Using AssertAll
[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-Spec

Ever had issues choosing the right Assert?
• IsTrue vs. AreEqual
• Parameter ordering confusion
• StringAssert/CollectionAssert
It’s all about proper error messages

Tool: 3rd party assertion libraries
Better error messages
Readability
Multiple asserts*
×Additional dependency
×Limited UT framework support
×System.Object “SPAMED” by extension messages

Shouldly
[Fact]
public void AddTest()
{
var calculator = new Calculator();
var result = calculator.Add(2, 3);
Assert.Equal(6, result);
}
[Fact]
public void AddTest_Shouldly()
{
var result = calculator.Add(2, 3);
result.ShouldBe(6);
}
https://github.com/shouldly/shouldly
Shouldly.ShouldAssertException
result
should be
6
but was
5
Xunit.Sdk.EqualException
Assert.Equal() Failure
Expected: 6
Actual: 5

Shouldly
[Fact]
public void GetDivisorsTest()
{
var result = calculator.GetDivisors(20);
Assert.Equal(new[] {2,3,5,7}, result);
}
[Fact]
public void GetDivisorsTest_Shouldly()
{
var result = calculator.GetDivisors(20);
result.ShouldBe(new[] { 2, 3, 5, 7 });
}
https://github.com/shouldly/shouldly
Shouldly.ShouldAssertException
result
should be
[2, 3, 5, 7]
but was
[2, 4, 5, 10]
difference
[2, *4*, 5, *10*]
Xunit.Sdk.EqualException
Assert.Equal() Failure
Expected: Int32[] [2, 3, 5, 7]
Actual: WhereEnumerableIterator<Int32> [2, 4, 5, 10]

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/

AssertHelper
[Test]
public void CheckCompare()
{
var myClass = new MyClass();
Expect.That(() => myClass.ReturnFive() == 10);
}
[Test]
public void CheckTrue()
{
var myClass = new MyClass();
Expect.That(() => myClass.ReturnFalse() == true);
}
[Test]
public void StringStartsWith() {
var s1 = "1234567890";
Expect.That(() => s1.StartsWith("456"));
}
[Test]
public void CollectionContains()
{
var c1 = new[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 0 };
Expect.That(() => c1.Contains(41));
}
https://github.com/dhelper/AssertHelper

Test organization

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/

Tool: BDDfy
[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();
}
}

Test execution

Everybody needs a CI server
Unit tests without a CI server are a waste of time
- if you're running all of the tests all of the time
locally you're a better man then I am

Tool: Continuous testing
DotCover
Typemock Runner
nCrunch

The right tools will help you write good tests
Arrange
Builder Pattern
AutoMocking
Containers
Export
Assert
Shouldly
FluentAssertions
AssertHelper
Test
Structure
BDDfy
Continuous
Testing
Typemock
Runner
DotCover
nCrunch

Thank you
Dror Helper | @dhelper | http://blog.drorhelper.com

Secret unit testing tools

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