XCTestAssertNoThrow (#184)

* Added implementation of XCTAssetNoThrow to XCTAssert.swift and tests

Author: ArtSabintsev

Sources/XCTest/Public/XCTAssert.swift

@@ -25,6 +25,7 @@ private enum _XCTAssertion {
     case `false`
     case fail
     case throwsError
+    case noThrow
 
     var name: String? {
         switch(self) {
@@ -41,6 +42,7 @@ private enum _XCTAssertion {
         case .`true`: return "XCTAssertTrue"
         case .`false`: return "XCTAssertFalse"
         case .throwsError: return "XCTAssertThrowsError"
+        case .noThrow: return "XCTAssertNoThrow"
         case .fail: return nil
         }
     }
@@ -421,3 +423,14 @@ public func XCTAssertThrowsError<T>(_ expression: @autoclosure () throws -> T, _
         }
     }
 }
+
+public func XCTAssertNoThrow<T>(_ expression: @autoclosure () throws -> T, _ message: @autoclosure () -> String = "", file: StaticString = #file, line: UInt = #line) {
+    _XCTEvaluateAssertion(.noThrow, message: message, file: file, line: line) {
+        do {
+             _ = try expression()
+            return .success
+        } catch let error {
+            return .expectedFailure("threw error \"\(error)\"")
+        }
+    }
+}

Tests/Functional/ErrorHandling/main.swift

@@ -26,6 +26,10 @@ class ErrorHandling: XCTestCase {
 
             // Tests for throwing assertion expressions
             ("test_assertionExpressionCanThrow", test_assertionExpressionCanThrow),
+
+            // Tests for XCTAssertNoThrow
+            ("test_shouldNotThrowErrorDefiningSuccess", test_shouldNotThrowErrorDefiningSuccess),
+            ("test_shouldThrowErrorDefiningFailure", test_shouldThrowErrorDefiningFailure),
         ]
     }()
 
@@ -103,13 +107,28 @@ class ErrorHandling: XCTestCase {
     func test_assertionExpressionCanThrow() {
         XCTAssertEqual(try functionThatShouldReturnButThrows(), 1)
     }
+
+
+// CHECK: Test Case 'ErrorHandling.test_shouldNotThrowErrorDefiningSuccess' started at \d+:\d+:\d+\.\d+
+// CHECK: Test Case 'ErrorHandling.test_shouldNotThrowErrorDefiningSuccess' passed \(\d+\.\d+ seconds\)
+    func test_shouldNotThrowErrorDefiningSuccess() {
+        XCTAssertNoThrow(try functionThatDoesNotThrowError())
+    }
+
+// CHECK: Test Case 'ErrorHandling.test_shouldThrowErrorDefiningFailure' started at \d+:\d+:\d+\.\d+
+// CHECK: .*/ErrorHandling/main.swift:[[@LINE+3]]: error: ErrorHandling.test_shouldThrowErrorDefiningFailure : XCTAssertNoThrow failed: threw error "anError\("an error message"\)" -
+// CHECK: Test Case 'ErrorHandling.test_shouldThrowErrorDefiningFailure' failed \(\d+\.\d+ seconds\)
+    func test_shouldThrowErrorDefiningFailure() {
+        XCTAssertNoThrow(try functionThatDoesThrowError())
+    }
 }
+
 // CHECK: Test Suite 'ErrorHandling' failed at \d+:\d+:\d+\.\d+
-// CHECK: \t Executed 6 tests, with 4 failures \(2 unexpected\) in \d+\.\d+ \(\d+\.\d+\) seconds
+// CHECK: \t Executed \d+ tests, with \d+ failures \(2 unexpected\) in \d+\.\d+ \(\d+\.\d+\) seconds
 
 XCTMain([testCase(ErrorHandling.allTests)])
 
 // CHECK: Test Suite '.*\.xctest' failed at \d+:\d+:\d+\.\d+
-// CHECK: \t Executed 6 tests, with 4 failures \(2 unexpected\) in \d+\.\d+ \(\d+\.\d+\) seconds
+// CHECK: \t Executed \d+ tests, with \d+ failures \(2 unexpected\) in \d+\.\d+ \(\d+\.\d+\) seconds
 // CHECK: Test Suite 'All tests' failed at \d+:\d+:\d+\.\d+
-// CHECK: \t Executed 6 tests, with 4 failures \(2 unexpected\) in \d+\.\d+ \(\d+\.\d+\) seconds
+// CHECK: \t Executed \d+ tests, with \d+ failures \(2 unexpected\) in \d+\.\d+ \(\d+\.\d+\) seconds