XCTest framework basics in Swift - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this XCTest assertion?

Consider the following XCTest code snippet. What will be the result when this test runs?

Swift

func testSum() {
    let result = 2 + 3
    XCTAssertEqual(result, 5)
    print("Test passed")
}

A Compilation error due to missing import XCTest

B Test failed with XCTAssertEqual failure

C Runtime error: undefined variable 'result'

D Test passed

💡 Hint

XCTAssertEqual checks if two values are equal. If they are, the test continues.

The assertion XCTAssertEqual(result, 5) passes because 2 + 3 equals 5. The print statement runs, outputting 'Test passed'.

🧠 Conceptual

intermediate

What is the purpose of the setUp() method in XCTest?

In XCTest, what does the setUp() method do?

A It runs once before all tests in the class to set up shared resources.

B It runs after each test method to clean up resources.

C It runs before each test method to prepare the test environment.

D It runs once after all tests in the class to tear down shared resources.

💡 Hint

Think about preparing fresh conditions for every test.

setUp() runs before each test method to ensure each test starts with a clean state.

🔧 Debug

advanced

Why does this XCTest fail to compile?

Identify the reason this XCTest code does not compile.

Swift

class MyTests: XCTestCase {
    func testExample() {
        XCTAssertTrue(5 > 3)
    }

    func setUp() {
        print("Setup called")
    }
}

A XCTAssertTrue requires a message parameter.

B setUp() must be marked with override keyword.

C testExample() must return a Bool value.

D XCTestCase class cannot have more than one method.

💡 Hint

Check method overriding rules in Swift classes.

setUp() overrides a method in XCTestCase and must be marked with override to compile.

📝 Syntax

advanced

Which option correctly defines a test method in XCTest?

Choose the correct syntax for a test method in an XCTestCase subclass.

A func testAddition() { XCTAssertEqual(1+1, 2) }

B func testAddition() throws { XCTAssertEqual(1+1, 2) }

C func testAddition() -> Bool { XCTAssertEqual(1+1, 2); return true }

D func testAddition() async { XCTAssertEqual(1+1, 2) }

💡 Hint

Test methods should not return values or be async/throws by default.

Test methods in XCTest are void functions without async or throws unless explicitly supported.

🚀 Application

expert

How many tests will run and what is the output?

Given this XCTestCase subclass, how many tests will run and what will be printed?

Swift

class SampleTests: XCTestCase {
    override func setUp() {
        super.setUp()
        print("Setup")
    }

    func testOne() {
        print("Test One")
        XCTAssertTrue(true)
    }

    func testTwo() {
        print("Test Two")
        XCTAssertTrue(false)
    }

    func helper() {
        print("Helper")
    }
}

A 2 tests run; output: Setup, Test One, Setup, Test Two; testTwo fails

B 3 tests run; output: Setup, Test One, Setup, Test Two, Setup, Helper; testTwo fails

C 2 tests run; output: Setup, Test One, Setup, Test Two; all tests pass

D 1 test runs; output: Setup, Test One; testOne passes

💡 Hint

Only methods starting with 'test' run as tests. setUp runs before each test.

Only testOne and testTwo run. setUp prints before each. testTwo fails due to XCTAssertTrue(false). helper() is not a test.