The document discusses refactoring tests to make them more readable and maintainable. It provides examples of a test for a registration form that is initially difficult to understand. Through refactoring techniques like extracting utility methods and reducing duplication, the test is simplified to clearly validate that a save button is disabled when the password is shorter than 6 characters. Refactoring tests in this way can prevent them from becoming a bottleneck in the development process.

1. Welcome!

2. Cenny
Davidsson

3. https://www.programmingbooks.dev
An Ordered and Curated Reading List for Software Craftsmanship Growth

4. Parakey

5. We are looking for team members:
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6. Annihilate test smells by refactoring to patterns

7. A procedure leading to acceptance or
rejection
— Kent Beck, Test-Driven Development: By Example

8. A smell is a symptom of a problem.
— Gerard Meszaros, xUnit Test Patterns: Refactoring
Test Code

9. Each pattern describes a problem which
occurs over and over again in our
environment, and then describes the core
of the solution to that problem, in such a
way that you can use this solution a million
times over, without ever doing it the same
way twice
— Christopher Alexander, A Pattern Language

10. Refactoring (verb): to restructure software
by applying a series of refactorings without
changing its observable behavior.
— Martin Fowler, Refactoring: Improving the Design
of Existing Code

11. Why?

12. Tests can quickly become a bottleneck in
an agile development process. This may not
be immediately obvious to those who have
never experienced the difference between
simple, easily understood tests and
complex, obtuse, hard-to-maintain tests.
— Gerard Meszaros, xUnit Test Patterns: Refactoring
Test Code

13. User Story
Guest must use a strong password
Disable save button when password is too weak (less
than 6 characters)

15. Let's do some Test-Driven Development!

17. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.make(register: { _, _ in })
sut.tableView.frame = CGRect(x: 0, y: 0, width: 100, height: 2000)
sut.loadViewIfNeeded()
let firstName = sut.tableView.cellForRow(at: IndexPath(row: 0, section: 0)).contentView.subviews.first as? UITextField
firstName?.text = "Scrooge"
firstName?.sendActions(for: .editingChanged)
let lastName = sut.tableView.cellForRow(at: IndexPath(row: 1, section: 0)).contentView.subviews.first as? UITextField
lastName?.text = "McDuck"
lastName?.sendActions(for: .editingChanged)
let password = sut.tableView.cellForRow(at: IndexPath(row: 0, section: 2)).contentView.subviews.first as? UITextField
password?.text = "money"
password?.sendActions(for: .editingChanged)
let terms = sut.tableView.cellForRow(at: IndexPath(row: 0, section: 3)).accessoryView as? UISwitch
terms?.isOn = true
terms?.sendActions(for: .valueChanged)
let saveButton = try XCTUnwrap(sut.navigationItem.rightBarButtonItem, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

18. Obscure Test
It is difficult to understand the test at a
glance.
— Gerard Meszaros, xUnit Test Patterns: Refactoring
Test Code

19. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.make(register: { _, _ in })
sut.tableView.frame = CGRect(x: 0, y: 0, width: 100, height: 2000)
sut.loadViewIfNeeded()
let firstName = sut.tableView.cellForRow(at: IndexPath(row: 0, section: 0)).contentView.subviews.first as? UITextField
firstName?.text = "Scrooge"
firstName?.sendActions(for: .editingChanged)
let lastName = sut.tableView.cellForRow(at: IndexPath(row: 1, section: 0)).contentView.subviews.first as? UITextField
lastName?.text = "McDuck"
lastName?.sendActions(for: .editingChanged)
let password = sut.tableView.cellForRow(at: IndexPath(row: 0, section: 2)).contentView.subviews.first as? UITextField
password?.text = "money"
password?.sendActions(for: .editingChanged)
let terms = sut.tableView.cellForRow(at: IndexPath(row: 0, section: 3)).accessoryView as? UISwitch
terms?.isOn = true
terms?.sendActions(for: .valueChanged)
let saveButton = try XCTUnwrap(sut.navigationItem.rightBarButtonItem, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

20. Test Utility Method
How do we reduce Test Code Duplication?
We encapsulate the test logic we want to reuse behind a suitably named utility method.
— Gerard Meszaros, xUnit Test Patterns: Refactoring
Test Code

21. SUT Encapsulation Method
reason for using a Test Utility Method is to encapsulate unnecessary knowledge of the
API of the SUT. What constitutes unnecessary? Any method we call on the SUT that is
not the method being tested creates additional coupling between the test and the SUT.
— Gerard Meszaros, xUnit Test Patterns: Refactoring
Test Code

22. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.make(register: { _, _ in })
sut.tableView.frame = CGRect(x: 0, y: 0, width: 100, height: 2000)
sut.loadViewIfNeeded()
let firstName = sut.tableView.cellForRow(at: IndexPath(row: 0, section: 0)).contentView.subviews.first as? UITextField
firstName?.text = "Scrooge"
firstName?.sendActions(for: .editingChanged)
let lastName = sut.tableView.cellForRow(at: IndexPath(row: 1, section: 0)).contentView.subviews.first as? UITextField
lastName?.text = "McDuck"
lastName?.sendActions(for: .editingChanged)
let password = sut.tableView.cellForRow(at: IndexPath(row: 0, section: 2)).contentView.subviews.first as? UITextField
password?.text = "money"
password?.sendActions(for: .editingChanged)
let terms = sut.tableView.cellForRow(at: IndexPath(row: 0, section: 3)).accessoryView as? UISwitch
terms?.isOn = true
terms?.sendActions(for: .valueChanged)
let saveButton = try XCTUnwrap(sut.navigationItem.rightBarButtonItem, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

23. extension UITableViewController {
func cell(at indexPath: IndexPath) -> UITableViewCell? {
tableView.cellForRow(at: indexPath)
}
}

24. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.make(register: { _, _ in })
sut.tableView.frame = CGRect(x: 0, y: 0, width: 100, height: 2000)
sut.loadViewIfNeeded()
let firstName = sut.tableView.cellForRow(at: IndexPath(row: 0, section: 0)).contentView.subviews.first as? UITextField
firstName?.text = "Scrooge"
firstName?.sendActions(for: .editingChanged)
let lastName = sut.tableView.cellForRow(at: IndexPath(row: 1, section: 0)).contentView.subviews.first as? UITextField
lastName?.text = "McDuck"
lastName?.sendActions(for: .editingChanged)
let password = sut.tableView.cellForRow(at: IndexPath(row: 0, section: 2)).contentView.subviews.first as? UITextField
password?.text = "money"
password?.sendActions(for: .editingChanged)
let terms = sut.tableView.cellForRow(at: IndexPath(row: 0, section: 3)).accessoryView as? UISwitch
terms?.isOn = true
terms?.sendActions(for: .valueChanged)
let saveButton = try XCTUnwrap(sut.navigationItem.rightBarButtonItem, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

25. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.make(register: { _, _ in })
sut.tableView.frame = CGRect(x: 0, y: 0, width: 100, height: 2000)
sut.loadViewIfNeeded()
let firstName = sut.cell(at: IndexPath(row: 0, section: 0)).contentView.subviews.first as? UITextField
firstName?.text = "Scrooge"
firstName?.sendActions(for: .editingChanged)
let lastName = sut.cell(at: IndexPath(row: 1, section: 0)).contentView.subviews.first as? UITextField
lastName?.text = "McDuck"
lastName?.sendActions(for: .editingChanged)
let password = sut.cell(at: IndexPath(row: 0, section: 2)).contentView.subviews.first as? UITextField
password?.text = "money"
password?.sendActions(for: .editingChanged)
let terms = sut.cell(at: IndexPath(row: 0, section: 3)).accessoryView as? UISwitch
terms?.isOn = true
terms?.sendActions(for: .valueChanged)
let saveButton = try XCTUnwrap(sut.navigationItem.rightBarButtonItem, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

26. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.make(register: { _, _ in })
sut.tableView.frame = CGRect(x: 0, y: 0, width: 100, height: 2000)
sut.loadViewIfNeeded()
let firstName = sut.cell(at: IndexPath(row: 0, section: 0)).contentView.subviews.first as? UITextField
firstName?.text = "Scrooge"
firstName?.sendActions(for: .editingChanged)
let lastName = sut.cell(at: IndexPath(row: 1, section: 0)).contentView.subviews.first as? UITextField
lastName?.text = "McDuck"
lastName?.sendActions(for: .editingChanged)
let password = sut.cell(at: IndexPath(row: 0, section: 2)).contentView.subviews.first as? UITextField
password?.text = "money"
password?.sendActions(for: .editingChanged)
let terms = sut.cell(at: IndexPath(row: 0, section: 3)).accessoryView as? UISwitch
terms?.isOn = true
terms?.sendActions(for: .valueChanged)
let saveButton = try XCTUnwrap(sut.navigationItem.rightBarButtonItem, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

27. extension UITableViewCell {
var textField: UITextField? {
contentView.subviews.first as? UITextField
}
}

28. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.make(register: { _, _ in })
sut.tableView.frame = CGRect(x: 0, y: 0, width: 100, height: 2000)
sut.loadViewIfNeeded()
let firstName = sut.cell(at: IndexPath(row: 0, section: 0)).contentView.subviews.first as? UITextField
firstName?.text = "Scrooge"
firstName?.sendActions(for: .editingChanged)
let lastName = sut.cell(at: IndexPath(row: 1, section: 0)).contentView.subviews.first as? UITextField
lastName?.text = "McDuck"
lastName?.sendActions(for: .editingChanged)
let password = sut.cell(at: IndexPath(row: 0, section: 2)).contentView.subviews.first as? UITextField
password?.text = "money"
password?.sendActions(for: .editingChanged)
let terms = sut.cell(at: IndexPath(row: 0, section: 3)).accessoryView as? UISwitch
terms?.isOn = true
terms?.sendActions(for: .valueChanged)
let saveButton = try XCTUnwrap(sut.navigationItem.rightBarButtonItem, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

29. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.make(register: { _, _ in })
sut.tableView.frame = CGRect(x: 0, y: 0, width: 100, height: 2000)
sut.loadViewIfNeeded()
let firstName = sut.cell(at: IndexPath(row: 0, section: 0)).textField
firstName?.text = "Scrooge"
firstName?.sendActions(for: .editingChanged)
let lastName = sut.cell(at: IndexPath(row: 1, section: 0)).textField
lastName?.text = "McDuck"
lastName?.sendActions(for: .editingChanged)
let password = sut.cell(at: IndexPath(row: 0, section: 2)).textField
password?.text = "money"
password?.sendActions(for: .editingChanged)
let terms = sut.cell(at: IndexPath(row: 0, section: 3)).accessoryView as? UISwitch
terms?.isOn = true
terms?.sendActions(for: .valueChanged)
let saveButton = try XCTUnwrap(sut.navigationItem.rightBarButtonItem, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

30. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.make(register: { _, _ in })
sut.tableView.frame = CGRect(x: 0, y: 0, width: 100, height: 2000)
sut.loadViewIfNeeded()
let firstName = sut.cell(at: IndexPath(row: 0, section: 0)).textField
firstName?.text = "Scrooge"
firstName?.sendActions(for: .editingChanged)
let lastName = sut.cell(at: IndexPath(row: 1, section: 0)).textField
lastName?.text = "McDuck"
lastName?.sendActions(for: .editingChanged)
let password = sut.cell(at: IndexPath(row: 0, section: 2)).textField
password?.text = "money"
password?.sendActions(for: .editingChanged)
let terms = sut.cell(at: IndexPath(row: 0, section: 3)).accessoryView as? UISwitch
terms?.isOn = true
terms?.sendActions(for: .valueChanged)
let saveButton = try XCTUnwrap(sut.navigationItem.rightBarButtonItem, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

31. extension UITextField {
func enter(text: String) {
self.text = text
sendActions(for: .editingChanged)
}
}

32. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.make(register: { _, _ in })
sut.tableView.frame = CGRect(x: 0, y: 0, width: 100, height: 2000)
sut.loadViewIfNeeded()
let firstName = sut.cell(at: IndexPath(row: 0, section: 0)).textField
firstName?.text = "Scrooge"
firstName?.sendActions(for: .editingChanged)
let lastName = sut.cell(at: IndexPath(row: 1, section: 0)).textField
lastName?.text = "McDuck"
lastName?.sendActions(for: .editingChanged)
let password = sut.cell(at: IndexPath(row: 0, section: 2)).textField
password?.text = "money"
password?.sendActions(for: .editingChanged)
let terms = sut.cell(at: IndexPath(row: 0, section: 3)).accessoryView as? UISwitch
terms?.isOn = true
terms?.sendActions(for: .valueChanged)
let saveButton = try XCTUnwrap(sut.navigationItem.rightBarButtonItem, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

33. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.make(register: { _, _ in })
sut.tableView.frame = CGRect(x: 0, y: 0, width: 100, height: 2000)
sut.loadViewIfNeeded()
let firstName = sut.cell(at: IndexPath(row: 0, section: 0)).textField
firstName?.enter(text: "Scrooge")
let lastName = sut.cell(at: IndexPath(row: 1, section: 0)).textField
lastName?.enter(text: "McDuck")
let password = sut.cell(at: IndexPath(row: 0, section: 2)).textField
password?.enter(text: "money")
let terms = sut.cell(at: IndexPath(row: 0, section: 3)).accessoryView as? UISwitch
terms?.isOn = true
terms?.sendActions(for: .valueChanged)
let saveButton = try XCTUnwrap(sut.navigationItem.rightBarButtonItem, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

34. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.make(register: { _, _ in })
sut.tableView.frame = CGRect(x: 0, y: 0, width: 100, height: 2000)
sut.loadViewIfNeeded()
let firstName = sut.cell(at: IndexPath(row: 0, section: 0)).textField
firstName?.enter(text: "Scrooge")
let lastName = sut.cell(at: IndexPath(row: 1, section: 0)).textField
lastName?.enter(text: "McDuck")
let password = sut.cell(at: IndexPath(row: 0, section: 2)).textField
password?.enter(text: "money")
let terms = sut.cell(at: IndexPath(row: 0, section: 3)).accessoryView as? UISwitch
terms?.isOn = true
terms?.sendActions(for: .valueChanged)
let saveButton = try XCTUnwrap(sut.navigationItem.rightBarButtonItem, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

35. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.make(register: { _, _ in })
sut.tableView.frame = CGRect(x: 0, y: 0, width: 100, height: 2000)
sut.loadViewIfNeeded()
let firstName = sut.cell(at: IndexPath(row: 0, section: 0)).textField
firstName?.enter(text: "Scrooge")
let lastName = sut.cell(at: IndexPath(row: 1, section: 0)).textField
lastName?.enter(text: "McDuck")
let password = sut.cell(at: IndexPath(row: 0, section: 2)).textField
password?.enter(text: "money")
let terms = sut.cell(at: IndexPath(row: 0, section: 3)).`switch`
terms?.toggle(true)
let saveButton = try XCTUnwrap(sut.navigationItem.rightBarButtonItem, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

36. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.make(register: { _, _ in })
sut.tableView.frame = CGRect(x: 0, y: 0, width: 100, height: 2000)
sut.loadViewIfNeeded()
let firstName = sut.cell(at: IndexPath(row: 0, section: 0)).textField
firstName?.enter(text: "Scrooge")
let lastName = sut.cell(at: IndexPath(row: 1, section: 0)).textField
lastName?.enter(text: "McDuck")
let password = sut.cell(at: IndexPath(row: 0, section: 2)).textField
password?.enter(text: "money")
let terms = sut.cell(at: IndexPath(row: 0, section: 3)).`switch`
terms?.toggle(true)
let saveButton = try XCTUnwrap(sut.navigationItem.rightBarButtonItem, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

37. IndexPath conforms to ExpressibleByArrayLiteral
public struct IndexPath: ReferenceConvertible, Equatable, Hashable, MutableCollection, RandomAccessCollection, Comparable, ExpressibleByArrayLiteral { ... }

38. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.make(register: { _, _ in })
sut.tableView.frame = CGRect(x: 0, y: 0, width: 100, height: 2000)
sut.loadViewIfNeeded()
let firstName = sut.cell(at: IndexPath(row: 0, section: 0)).textField
firstName?.enter(text: "Scrooge")
let lastName = sut.cell(at: IndexPath(row: 1, section: 0)).textField
lastName?.enter(text: "McDuck")
let password = sut.cell(at: IndexPath(row: 0, section: 2)).textField
password?.enter(text: "money")
let terms = sut.cell(at: IndexPath(row: 0, section: 3)).`switch`
terms?.toggle(true)
let saveButton = try XCTUnwrap(sut.navigationItem.rightBarButtonItem, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

39. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.make(register: { _, _ in })
sut.tableView.frame = CGRect(x: 0, y: 0, width: 100, height: 2000)
sut.loadViewIfNeeded()
let firstName = sut.cell(at: [0, 0]).textField
firstName?.enter(text: "Scrooge")
let lastName = sut.cell(at: [0, 1]).textField
lastName?.enter(text: "McDuck")
let password = sut.cell(at: [2, 0]).textField
password?.enter(text: "money")
let terms = sut.cell(at: [3, 0]).`switch`
terms?.toggle(true)
let saveButton = try XCTUnwrap(sut.navigationItem.rightBarButtonItem, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

40. extension RegisterViewController {
func enter(firstName: String, lastName: String, password: String) {
let firstName = sut.cell(at: [0, 0]).textField
firstName?.enter(text: firstName)
let lastName = sut.cell(at: [0, 1]).textField
lastName?.enter(text: lastName)
let password = sut.cell(at: [2, 0]).textField
password?.enter(text: password)
}
}

41. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.make(register: { _, _ in })
sut.tableView.frame = CGRect(x: 0, y: 0, width: 100, height: 2000)
sut.loadViewIfNeeded()
let firstName = sut.cell(at: [0, 0]).textField
firstName?.enter(text: "Scrooge")
let lastName = sut.cell(at: [0, 1]).textField
lastName?.enter(text: "McDuck")
let password = sut.cell(at: [2, 0]).textField
password?.enter(text: "money")
let terms = sut.cell(at: [3, 0]).`switch`
terms?.toggle(true)
let saveButton = try XCTUnwrap(sut.navigationItem.rightBarButtonItem, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

42. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.make(register: { _, _ in })
sut.tableView.frame = CGRect(x: 0, y: 0, width: 100, height: 2000)
sut.loadViewIfNeeded()
sut.enter(firstName: "Scrooge", lastName: "McDuck", password: "money")
let terms = sut.cell(at: [3, 0]).`switch`
terms?.toggle(true)
let saveButton = try XCTUnwrap(sut.navigationItem.rightBarButtonItem, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

43. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.make(register: { _, _ in })
sut.tableView.frame = CGRect(x: 0, y: 0, width: 100, height: 2000)
sut.loadViewIfNeeded()
sut.enter(firstName: "Scrooge", lastName: "McDuck", password: "money")
sut.termsOfService(isAccepted: true)
let saveButton = try XCTUnwrap(sut.navigationItem.rightBarButtonItem, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

44. Creation Method
How do we construct the Fresh Fixture?
We set up the test fixture by calling methods that hide the mechanics of building ready-
to-use objects behind Intent-Revealing Names.
— Gerard Meszaros, xUnit Test Patterns: Refactoring
Test Code

45. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.make(register: { _, _ in })
sut.tableView.frame = CGRect(x: 0, y: 0, width: 100, height: 2000)
sut.loadViewIfNeeded()
sut.enter(firstName: "Scrooge", lastName: "McDuck", password: "money")
sut.termsOfService(isAccepted: true)
let saveButton = try XCTUnwrap(sut.navigationItem.rightBarButtonItem, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

46. extension RegisterViewController {
static func fixture() -> RegisterViewController {
let viewController = RegisterViewController.make(register: { _, _ in })
viewController.tableView.frame = CGRect(x: 0, y: 0, width: 100, height: 2000)
viewController.loadViewIfNeeded()
return viewController
}
}

47. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.make(register: { _, _ in })
sut.tableView.frame = CGRect(x: 0, y: 0, width: 100, height: 2000)
sut.loadViewIfNeeded()
sut.enter(firstName: "Scrooge", lastName: "McDuck", password: "money")
sut.termsOfService(isAccepted: true)
let saveButton = try XCTUnwrap(sut.navigationItem.rightBarButtonItem, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

48. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.fixture()
sut.enter(firstName: "Scrooge", lastName: "McDuck", password: "money")
sut.termsOfService(isAccepted: true)
let saveButton = try XCTUnwrap(sut.navigationItem.rightBarButtonItem, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

49. extension RegisterViewController {
var saveButton: UIBarButtonItem? {
navigationItem.rightBarButtonItem
}
}

50. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.fixture()
sut.enter(firstName: "Scrooge", lastName: "McDuck", password: "money")
sut.termsOfService(isAccepted: true)
let saveButton = try XCTUnwrap(sut.navigationItem.rightBarButtonItem, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

51. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.fixture()
sut.enter(firstName: "Scrooge", lastName: "McDuck", password: "money")
sut.termsOfService(isAccepted: true)
let saveButton = try XCTUnwrap(sut.saveButton, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

52. Custom Assertion
How do we make tests self-checking when we have test-specific equality logic? How do
we reduce Test Code Duplication when the same assertion
logic appears in many tests?
How do we avoid Conditional Test Logic?
We create a purpose-built Assertion Method that compares only those attributes of the
object that define test-specific equality.
— Gerard Meszaros, xUnit Test Patterns: Refactoring
Test Code

53. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.fixture()
sut.enter(firstName: "Scrooge", lastName: "McDuck", password: "money")
sut.termsOfService(isAccepted: true)
let saveButton = try XCTUnwrap(sut.saveButton, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

54. func assertDisabled(_ button: UIBarButtonItem?) {
guard let button = button else {
XCTFail("Found nil instead of item")
}
XCTAssertFalse(button.isEnabled, "Item is enabled")
}

55. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.fixture()
sut.enter(firstName: "Scrooge", lastName: "McDuck", password: "money")
sut.termsOfService(isAccepted: true)
let saveButton = try XCTUnwrap(sut.saveButton, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

56. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.fixture()
sut.enter(firstName: "Scrooge", lastName: "McDuck", password: "money")
sut.termsOfService(isAccepted: true)
assertDisabled(sut.saveButton)
}

57. // Refactored
func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.fixture()
sut.enter(firstName: "Scrooge", lastName: "McDuck", password: "money")
sut.termsOfService(isAccepted: true)
assertDisabled(sut.saveButton)
}
// Old
func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.make(register: { _, _ in })
sut.tableView.frame = CGRect(x: 0, y: 0, width: 100, height: 2000)
sut.loadViewIfNeeded()
let firstName = sut.tableView.cellForRow(at: IndexPath(row: 0, section: 0)).contentView.subviews.first as? UITextField
firstName?.text = "Scrooge"
firstName?.sendActions(for: .editingChanged)
let lastName = sut.tableView.cellForRow(at: IndexPath(row: 1, section: 0)).contentView.subviews.first as? UITextField
lastName?.text = "McDuck"
lastName?.sendActions(for: .editingChanged)
let password = sut.tableView.cellForRow(at: IndexPath(row: 0, section: 2)).contentView.subviews.first as? UITextField
password?.text = "money"
password?.sendActions(for: .editingChanged)
let terms = sut.tableView.cellForRow(at: IndexPath(row: 0, section: 3)).accessoryView as? UISwitch
terms?.isOn = true
terms?.sendActions(for: .valueChanged)
let saveButton = try XCTUnwrap(sut.navigationItem.rightBarButtonItem, "Found nil instead of item")
XCTAssertFalse(saveButton.isEnabled, "Item is enabled")
}

58. Should we stop here?

59. It depends!

60. func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.fixture()
sut.enter(firstName: "Scrooge", lastName: "McDuck", password: "money")
sut.termsOfService(isAccepted: true)
assertDisabled(sut.saveButton)
}
func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.fixture()
sut.enter(firstName: "Scrooge", lastName: "McDuck", password: "m")
sut.termsOfService(isAccepted: true)
assertDisabled(sut.saveButton)
}
func test_shorter_than_length_6_password_disables_save_button() throws {
let sut = RegisterViewController.fixture()
sut.enter(firstName: "Scrooge", lastName: "McDuck", password: "")
sut.termsOfService(isAccepted: true)
assertDisabled(sut.saveButton)
}

61. The Rule of Three .... The third time you do
something similar, you refactor.
— Martin Fowler, Refactoring: Improving the Design
of Existing Code

62. Parameterized Test
How do we reduce Test Code Duplication when the same test logic appears in many
tests?
We pass the information needed to do fixture setup and result verification to a utility
method that implements the entire test life cycle.
— Gerard Meszaros, xUnit Test Patterns: Refactoring
Test Code

63. func test_shorter_than_length_6_password_disables_save_button() throws {
verifySaveButtonDisabled(password: "money")
verifySaveButtonDisabled(password: "m")
verifySaveButtonDisabled(password: "")
}
private func verifySaveButtonDisabled(password: String) throws {
let sut = RegisterViewController.fixture()
sut.enter(firstName: "Scrooge", lastName: "McDuck", password: password)
sut.termsOfService(isAccepted: true)
assertDisabled(sut.saveButton)
}

64. func test_shorter_than_length_6_password_disables_save_button() throws {
verifySaveButtonDisabled(password: "money")
verifySaveButtonDisabled(password: "m")
verifySaveButtonDisabled(password: "")
}
private func verifySaveButtonDisabled(password: String, file: StaticString = #file, line: UInt = #line) throws {
let sut = RegisterViewController.fixture()
sut.enter(firstName: "Scrooge", lastName: "McDuck", password: password)
sut.termsOfService(isAccepted: true)
assertDisabled(sut.saveButton, file: file, line: line)
}

65. Questions?

66. When is the
next meetup?

67. Thank you for
coming!