Unit testing ViewModels in iOS Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a test class for a ViewModel in Swift.

iOS Swift

class [1]: XCTestCase {
}

Drag options to blanks, or click blank then click option'

AMyViewModelTests

BViewModel

CTestViewModel

DViewModelTestCase

Attempts:

3 left

💡 Hint

Common Mistakes

Using a generic class name like 'ViewModel' without 'Tests'.

Not inheriting from XCTestCase (not shown here but important).

The test class should be named clearly to indicate it tests the ViewModel, commonly ending with Tests.

2fill in blank

medium

Complete the code to create an instance of the ViewModel inside the test class.

iOS Swift

var viewModel: [1]!

override func setUp() {
  super.setUp()
  viewModel = [1]()
}

Drag options to blanks, or click blank then click option'

AViewModelTests

BMyViewModel

CXCTestCase

DTestViewModel

Attempts:

3 left

💡 Hint

Common Mistakes

Using the test class name instead of the ViewModel class.

Not initializing the ViewModel in setUp.

The ViewModel instance should be of the actual ViewModel class, here named MyViewModel.

3fill in blank

hard

Fix the error in the test method to check if the ViewModel's title is correct.

iOS Swift

func testTitle() {
  let expected = "Welcome"
  XCTAssertEqual(viewModel.[1], expected)
}

Drag options to blanks, or click blank then click option'

AtitleText

Btitle()

CgetTitle()

Dtitle

Attempts:

3 left

💡 Hint

Common Mistakes

Using method call syntax for a property.

Using a wrong property name.

The property to test is usually named title without parentheses if it is a property, not a method.

4fill in blank

hard

Fill both blanks to test if the ViewModel updates its count correctly after increment.

iOS Swift

func testIncrement() {
  viewModel.increment()
  XCTAssertEqual(viewModel.[1], [2])
}

Drag options to blanks, or click blank then click option'

Acount

B1

C0

Dincrement

Attempts:

3 left

💡 Hint

Common Mistakes

Checking the wrong property.

Expecting the count to be 0 after increment.

The test checks if the count property equals 1 after calling increment().

5fill in blank

hard

Fill all three blanks to test if the ViewModel filters items correctly.

iOS Swift

func testFilterItems() {
  let filtered = viewModel.items.filter { $0.[1].[2]([3]) }
  XCTAssertEqual(filtered.count, 2)
}

Drag options to blanks, or click blank then click option'

Aname

Bcontains

C"a"

DisEmpty

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'isEmpty' instead of 'contains'.

Filtering on the wrong property.

The test filters items whose name contains the letter "a".