Assertions (XCTAssertEqual, XCTAssertTrue) in Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if two values are equal using XCTAssertEqual.

Swift

XCTAssertEqual([1], 5)

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

Aresult

Bprint

Ctrue

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Using a literal like 5 as the first argument instead of the variable.

Using XCTAssertTrue instead of XCTAssertEqual for value comparison.

Use XCTAssertEqual to compare the variable result with the expected value 5.

2fill in blank

medium

Complete the code to assert that a condition is true using XCTAssertTrue.

Swift

XCTAssertTrue([1])

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

Aresult = 10

Bprint(result)

Cfalse

Dresult == 10

Attempts:

3 left

💡 Hint

Common Mistakes

Using assignment (=) instead of comparison (==).

Passing a function call like print() instead of a boolean condition.

XCTAssertTrue expects a condition that evaluates to true. Here, we check if result equals 10.

3fill in blank

hard

Fix the error in the assertion to correctly check if two strings are equal.

Swift

XCTAssertEqual([1], "Hello")

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

Agreeting

Bgreeting()

Cprint(greeting)

Dtrue

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses after the variable name as if it were a function.

Passing print statements inside XCTAssertEqual.

Pass the variable greeting directly to XCTAssertEqual to compare it with the string "Hello".

4fill in blank

hard

Fill both blanks to assert that the count of items is greater than zero.

Swift

XCTAssertTrue([1] [2] 0)

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

Aitems.count

B==

C>

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using equality (==) instead of greater than (>).

Using less than (<) which would check the wrong condition.

We check if items.count is greater than zero using XCTAssertTrue.

5fill in blank

hard

Fill all three blanks to assert that the uppercase version of a string equals "WORLD".

Swift

XCTAssertEqual([1].[2](), "[3]")

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

Aword

Buppercased

CWORLD

Dlowercased

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercased() instead of uppercased().

Comparing to the wrong string value.

We call uppercased() on the variable word and check if it equals "WORLD" using XCTAssertEqual.

Practice

1. What does XCTAssertEqual(a, b) check in a Swift test?

easy

A. It checks if a and b are equal.

B. It checks if a is greater than b.

C. It checks if a is less than b.

D. It checks if a is not equal to b.

Solution

1. Step 1: Understand XCTAssertEqual purpose

   XCTAssertEqual is used to compare two values for equality in tests.

2. Step 2: Match the function behavior

   It returns success if both values are equal, otherwise it fails the test.

3. Final Answer:

   It checks if a and b are equal. -> Option A

4. Quick Check:

   XCTAssertEqual checks equality = B [OK]

Hint: XCTAssertEqual means values must be the same [OK]

Common Mistakes:

• Confusing XCTAssertEqual with greater or less than checks
• Thinking it checks inequality
• Mixing it up with XCTAssertTrue

2. Which of the following is the correct syntax to check if a boolean variable isReady is true using XCTest?

easy

A. XCTAssertFalse(isReady)

B. XCTAssertEqual(isReady == true)

C. XCTAssert(isReady == true)

D. XCTAssertTrue(isReady)

Solution

1. Step 1: Identify the correct assertion for boolean true

   XCTAssertTrue is designed to check if a condition is true.

2. Step 2: Compare options

   XCTAssertTrue(isReady) uses XCTAssertTrue directly on isReady, which is the simplest and correct syntax.

3. Final Answer:

   XCTAssertTrue(isReady) -> Option D

4. Quick Check:

   Use XCTAssertTrue for true checks = A [OK]

Hint: Use XCTAssertTrue(variable) to check if true [OK]

Common Mistakes:

• Using XCTAssertFalse instead of XCTAssertTrue
• Using XCTAssertEqual unnecessarily for booleans
• Writing XCTAssert without True or False

3. What will happen when this test runs?

let result = 5 + 3
XCTAssertEqual(result, 8)

medium

A. The test will pass because 5 + 3 equals 8.

B. The test will fail because 5 + 3 does not equal 8.

C. The test will cause a syntax error.

D. The test will crash at runtime.

Solution

1. Step 1: Calculate the expression

   5 + 3 equals 8, so result is 8.

2. Step 2: Check XCTAssertEqual condition

   XCTAssertEqual compares result (8) with 8, which are equal, so the test passes.

3. Final Answer:

   The test will pass because 5 + 3 equals 8. -> Option A

4. Quick Check:

   5 + 3 = 8, XCTAssertEqual passes = A [OK]

Hint: Calculate values, then check equality assertion [OK]

Common Mistakes:

• Assuming test fails without checking actual values
• Confusing syntax error with test failure
• Thinking XCTAssertEqual compares types only

4. Identify the error in this test code:

let isActive = false
XCTAssertTrue(isActive)

medium

A. No error; the test will pass.

B. XCTAssertTrue cannot be used with boolean variables.

C. The test will fail because isActive is false but XCTAssertTrue expects true.

D. Syntax error due to missing parentheses.

Solution

1. Step 1: Check the value of isActive

   isActive is set to false.

2. Step 2: Understand XCTAssertTrue behavior

   XCTAssertTrue expects its argument to be true; since isActive is false, the test will fail.

3. Final Answer:

   The test will fail because isActive is false but XCTAssertTrue expects true. -> Option C

4. Quick Check:

   False value with XCTAssertTrue causes failure = D [OK]

Hint: XCTAssertTrue fails if condition is false [OK]

Common Mistakes:

• Thinking test passes when condition is false
• Confusing syntax error with test failure
• Believing XCTAssertTrue only works with expressions

5. You want to test a function isEven(_ number: Int) -> Bool that returns true if a number is even. Which assertion correctly tests that isEven(4) returns true?

hard

A. XCTAssertEqual(isEven(4), true)

B. Both A and B are correct

C. XCTAssertTrue(isEven(4))

D. XCTAssertFalse(isEven(4))

Solution

1. Step 1: Understand the function output

   isEven(4) returns true because 4 is even.

2. Step 2: Check assertion options

   XCTAssertEqual(isEven(4), true) uses XCTAssertEqual to compare with true, which works.
   XCTAssertTrue(isEven(4)) uses XCTAssertTrue directly on the result, which also works.

3. Step 3: Determine correct choice

   Both assertions correctly test that the function returns true.

4. Final Answer:

   Both A and B are correct -> Option B

5. Quick Check:

   Both XCTAssertEqual and XCTAssertTrue work for true checks = C [OK]

Hint: XCTAssertEqual and XCTAssertTrue both check true values [OK]

Common Mistakes:

• Choosing only one assertion as correct
• Using XCTAssertFalse incorrectly
• Confusing equality with boolean checks