Playground TDD

playground.swift

import XCTest

class PlaygroundTestObserver: NSObject, XCTestObservation {
  @objc func testCase(_ testCase: XCTestCase, didFailWithDescription description: String, inFile filePath: String?, atLine lineNumber: UInt) {
    print("Test failed on line \(lineNumber): \(testCase.name), \(description)")
  }
}

struct TestRunner {
  func runTests(testClass: AnyClass) {
    print("Running test suite \(testClass)")

    let tests = testClass as! XCTestCase.Type
    let testSuite = tests.defaultTestSuite()
    testSuite.run()
    let run = testSuite.testRun as! XCTestSuiteRun

    print("Ran \(run.executionCount) tests in \(run.testDuration) with \(run.totalFailureCount) failures")
  }
}

class ExampleTests: XCTestCase {
  func testShouldFail() {
    XCTFail("This will fail")
  }
  func testShouldPass() {
    XCTAssertEqual(1,1)
  }
}

let observer = PlaygroundTestObserver()
let center = XCTestObservationCenter.shared()
center.addTestObserver(observer)

TestRunner().runTests(testClass: ExampleTests.self)