Tests for an extension to 'Int' with a built in NumberFormatter()

CurrencyFormattingDemoTests.swift

//
//  CurrencyFormattingDemoTests.swift
//  CurrencyFormattingDemoTests
//
//  Created by Brian Manning on 2/28/23.
//

import XCTest
@testable import CurrencyFormattingDemo

final class CurrencyFormattingDemoTests: XCTestCase {

    // fails to compile: "'nil' cannot initialize specified type 'Int'"
//    func test_toCurrencyFormattedString_withNil_returnsZero() throws {
//        let testInt: Int = nil
//        let testString = testInt.toCurrencyFormattedString()
//        XCTAssertEqual("0.00", testString)
//    }

    func test_toCurrencyFormattedString_withZero_returnsZero() throws {
        let testInt = 0
        let testString = testInt.toCurrencyFormattedString()
        XCTAssertEqual("0.00", testString)
    }

    func test_toCurrencyFormattedString_withNegativeOne_returnsNegativePointZeroOne() {
        let testInt = -1
        let testString = testInt.toCurrencyFormattedString()
        XCTAssertEqual("-0.01", testString)
    }

    func test_toCurrencyFormattedString_withBigInt_returnsNegativePointZeroOne() {
        let testInt = 2_147_483_648
        let testString = testInt.toCurrencyFormattedString()
        XCTAssertEqual("21,474,836.48", testString)
    }

    func test_toCurrencyFormattedString_withBigNegativeInt_returnsNegativePointZeroOne() {
        let testInt: Int = -2_147_483_648
        let testString = testInt.toCurrencyFormattedString()
        XCTAssertEqual("-21,474,836.48", testString)
    }

    func test_toCurrencyFormattedString_withMaxInt_returnsNegativePointZeroOne() {
        let testInt = Int(Int64.max)
        let testString = testInt.toCurrencyFormattedString()
        XCTAssertEqual("92,233,720,368,547,760.00", testString)
    }

    func test_toCurrencyFormattedString_withMinInt_returnsNegativePointZeroOne() {
        let testInt = Int(Int64.min)
        let testString = testInt.toCurrencyFormattedString()
        XCTAssertEqual("-92,233,720,368,547,760.00", testString)
    }

    // fails to compile; "arithmetic overflow"
//    func test_toCurrencyFormattedString_withMaxIntPlusOne_failsToCompile() {
//        let testInt = Int(Int64.max) + 1
//        let testString = testInt.toCurrencyFormattedString()
//        XCTAssertEqual("92,233,720,368,547,760.00", testString)
//    }

}