Unit Test 관련

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Intro

• Unit tests are means of testing small bits of code
• This works well to reduce bugs in new and existing features
• A unit test is essentially a function that invokes some code and asserts that certain conditions are satisfied during code execution

xctest

• Xcode's testing framework for unit testing
• Integerates seamlessly with Xcode's testing workflow
• XCTests can be added when creating a new project or through [File] > [New] > [Target] > [Unit Testing Bundle]

xctest class

• Adding @testable attribute to import statement provides elevated access
• setUp() is called before each tests are run
• tearDownWithError() provides an opportunity to perform cleanup and to throw errors after each test

import XCTest
@testable import BMI_Calculator

class PROJECTNAMETests: XCTestCase {
    override func setUpWithError() throws {
        
    }
    override func tearDownWithError() throws {
        
    }
}

Example

• Test should be written as functions, the below struct calculates a user BMI - function need to be named as test..()

struct BMICalculator {
    var weightKG: Int
    var heightM: Double
    func returnBMI() -> Double {
        return Double(weightKG) / (heightM * heightM)
    }
}

class BMI_CalculatorTests: XCTestCase {
    func testBMI() {
        let bmiTest = BMICalculator(weightKG: 68, heightM: 1.77)
        let result = bmiTest.returnBMI()
        XCTAssertEqual(result, 21.70512943279896)
    }
}

Notable XCTAssert

• There are seeveral XCTAsserts worth using, the xample below highlights a few of them:

func testNotableXCTAssert() {
    // Bool
    let falseBoolResult = false
    XCTAssertFalse(falseBoolResult)

    // Nil
    let nilResult: String? = nil
    XCTAssertNil(nilResult)

    // Greater Than / Less Than
    let greaterThanResult = 12
    XCTAssertGreaterThanOrEqual(graterThanResult, 11)

    // Strings
    let notEqualString = "Example"
    XCTAssertNotEqual(notEqualString, "Test?")
}

Summary

• Testing reduces bugs - especially on larger project with several developers
• Unit tests CAN be skipped or disabled
• All unit tests are functions that MUST include "test" in the function name
• Keep tests simple so that you're only testing a unit.