Merge pull request #4 from antitypical/test-assertion-failures

Test assertion failures

AssertionsTests/AssertionsTests.swift

@@ -1,38 +1,120 @@
 //  Copyright (c) 2015 Rob Rix. All rights reserved.
 
-import Assertions
-import XCTest
-
 final class AssertionsTests: XCTestCase {
 	func testAssertingWithOptionalArrays() {
 		let array: [Int]? = [1, 2, 3]
 		assert(array, ==, [1, 2, 3])
 //		XCTAssertEqual(array, [1, 2, 3]) // => error: value of optional type '[Int]?' not unwrapped; did you mean to use '!' or '?'?
 	}
 
+	func testAssertingWithOptionalArraysFailure() {
+		let array: [Int]? = [1, 2, 3]
+		assertFailure {
+			assert(array, ==, [1, 2, 3, 4])
+		}
+	}
+
+
 	func testAssertingWithOptionalStrings() {
 		let string: String? = "hello"
 		assert(string, ==, "hello")
 //		XCTAssertEqual(string, "hello") // => error: cannot find an overload for 'XCTAssertEqual' that accepts an argument list of type '(String?, String)'
 	}
 
+	func testAssertingWithOptionalStringsFailure() {
+		let string: String? = "hello"
+		assertFailure {
+			assert(string, ==, "hello!")
+		}
+	}
+
+
 	func testAssertingWithMethods() {
 		let set: Set<Int>? = Set([1, 2, 3])
 		assert(set, Set.contains, 3)
 	}
 
+	func testAssertingWithMethodsFailure() {
+		let set: Set<Int>? = Set([1, 2, 3])
+		assertFailure {
+			assert(set, Set.contains, 4)
+		}
+	}
+
+
 	func testAssertingPropertyWithPredicate() {
 		let string: String? = ""
 		assert(string, { $0.isEmpty })
 	}
 
+	func testAssertingPropertyWithPredicateFailure() {
+		let string: String? = "1"
+		assertFailure {
+			assert(string, { $0.isEmpty })
+		}
+	}
+
+
 	func testAssertingNilOfEquatableType() {
 		let x: Int? = nil
 		assert(x, ==, nil)
 	}
 
+	func testAssertingNilOfEquatableTypeFailure() {
+		let x: Int? = 1
+		assertFailure {
+			assert(x, ==, nil)
+		}
+	}
+
 	func testAssertingNonNilOfEquatableType() {
 		let x: Int? = 1
 		assert(x, !=, nil)
 	}
+
+	func testAssertingNonNilOfEquatableTypeFailure() {
+		let x: Int? = nil
+		assertFailure(x, !=, nil)
+	}
+
+
+	// MARK: Testing assertion failures
+
+	/// Assert that `test` causes an assertion failure.
+	func assertFailure(file: String = __FILE__, line: UInt = __LINE__, @noescape _ test: () -> ()) -> (message: String, file: String, line: UInt, expected: Bool)? {
+		let previous = expectFailure
+		expectFailure = true
+		test()
+		expectFailure = previous
+		if let result = failure {
+			return result
+		} else {
+			XCTFail("expected the assertion to fail", file: file, line: line)
+			return nil
+		}
+	}
+
+	/// Workaround for http://www.openradar.me/19996972
+	func assertFailure<T>(@autoclosure expression1: () -> T, _ test: (T, T) -> Bool, @autoclosure _ expression2: () -> T, message: String = "", file: String = __FILE__, line: UInt = __LINE__) -> (message: String, file: String, line: UInt, expected: Bool)? {
+		return assertFailure {
+			assert(expression1(), test, expression2(), message: message, file: file, line: line)
+		}
+	}
+
+	private var expectFailure: Bool = false
+	private var failure: (message: String, file: String, line: UInt, expected: Bool)? = nil
+
+	override func recordFailureWithDescription(message: String!, inFile file: String!, atLine line: UInt, expected: Bool) {
+		if expectFailure {
+			failure = (message: message, file: file, line: line, expected: expected)
+		} else {
+			super.recordFailureWithDescription(message, inFile: file, atLine: line, expected: expected)
+		}
+	}
 }
+
+
+// MARK: - Imports
+
+import Assertions
+import XCTest