Test the failure messages for optional and non-optional XCTAssertEqual variants

Author: briancroom

validation-test/stdlib/XCTest.swift

@@ -21,8 +21,24 @@ var XCTestTestSuite = TestSuite("XCTest")
 //       instantiate an NSInvocation with the given selector.
 
 
-func execute(_ run: () -> ()) {
+func execute(observers: [XCTestObservation] = [], _ run: () -> Void) {
+  for observer in observers {
+    XCTestObservationCenter.shared().addTestObserver(observer)
+  }
+
   run()
+
+  for observer in observers {
+    XCTestObservationCenter.shared().removeTestObserver(observer)
+  }
+}
+
+class FailureDescriptionObserver: NSObject, XCTestObservation {
+  var failureDescription: String?
+
+  func testCase(_ testCase: XCTestCase, didFailWithDescription description: String, inFile filePath: String?, atLine lineNumber: UInt) {
+    failureDescription = description
+  }
 }
 
 XCTestTestSuite.test("exceptions") {
@@ -44,6 +60,31 @@ XCTestTestSuite.test("exceptions") {
   expectFalse(testRun.hasSucceeded)
 }
 
+XCTestTestSuite.test("XCTAssertEqual/T") {
+  class AssertEqualTestCase: XCTestCase {
+    dynamic func test_whenEqual_passes() {
+      XCTAssertEqual(1, 1)
+    }
+
+    dynamic func test_whenNotEqual_fails() {
+      XCTAssertEqual(1, 2)
+    }
+  }
+
+  let passingTestCase = AssertEqualTestCase(selector: #selector(AssertEqualTestCase.test_whenEqual_passes))
+  execute(passingTestCase.run)
+  let passingTestRun = passingTestCase.testRun!
+  expectTrue(passingTestRun.hasSucceeded)
+
+  let failingTestCase = AssertEqualTestCase(selector: #selector(AssertEqualTestCase.test_whenNotEqual_fails))
+  let observer = FailureDescriptionObserver()
+  execute(observers: [observer], failingTestCase.run)
+  let failingTestRun = failingTestCase.testRun!
+  expectEqual(1, failingTestRun.failureCount)
+  expectEqual(0, failingTestRun.unexpectedExceptionCount)
+  expectEqual(observer.failureDescription, "XCTAssertEqual failed: (\"1\") is not equal to (\"2\") - ")
+}
+
 XCTestTestSuite.test("XCTAssertEqual/Optional<T>") {
   class AssertEqualOptionalTestCase: XCTestCase {
     dynamic func test_whenOptionalsAreEqual_passes() {
@@ -66,14 +107,16 @@ XCTestTestSuite.test("XCTAssertEqual/Optional<T>") {
   expectTrue(passingTestRun.hasSucceeded)
 
   let failingTestCase = AssertEqualOptionalTestCase(selector: #selector(AssertEqualOptionalTestCase.test_whenOptionalsAreNotEqual_fails))
-  execute(failingTestCase.run)
+  let observer = FailureDescriptionObserver()
+  execute(observers: [observer], failingTestCase.run)
   let failingTestRun = failingTestCase.testRun!
   expectEqual(1, failingTestRun.testCaseCount)
   expectEqual(1, failingTestRun.executionCount)
   expectEqual(1, failingTestRun.failureCount)
   expectEqual(0, failingTestRun.unexpectedExceptionCount)
   expectEqual(1, failingTestRun.totalFailureCount)
   expectFalse(failingTestRun.hasSucceeded)
+  expectEqual(observer.failureDescription, "XCTAssertEqual failed: (\"Optional(1)\") is not equal to (\"Optional(2)\") - ")
 }
 
 XCTestTestSuite.test("XCTAssertEqual/Array<T>") {