Fix the failure message emitted by XCTAssertNotNil

Author: briancroom

Sources/XCTest/XCTAssert.swift

@@ -358,7 +358,7 @@ public func XCTAssertNotEqualWithAccuracy<T: FloatingPointType>(@autoclosure exp
 }
 
 public func XCTAssertNotNil(@autoclosure expression: () throws -> Any?, @autoclosure _ message: () -> String = "", file: StaticString = #file, line: UInt = #line) {
-    _XCTEvaluateAssertion(.Nil, message: message, file: file, line: line) {
+    _XCTEvaluateAssertion(.NotNil, message: message, file: file, line: line) {
         let value = try expression()
         if value != nil {
             return .Success

Tests/Functional/FailureMessagesTestCase/main.swift

@@ -59,7 +59,7 @@
 // CHECK: test.swift:181: error: FailureMessagesTestCase.testAssertNotEqualWithAccuracy : XCTAssertNotEqualWithAccuracy failed: \("1\.0"\) is equal to \("1\.0"\) \+/- \("0\.1"\) - message
 // CHECK: Test Case 'FailureMessagesTestCase.testAssertNotEqualWithAccuracy' failed \(\d+\.\d+ seconds\).
 // CHECK: Test Case 'FailureMessagesTestCase.testAssertNotNil' started.
-// CHECK: test.swift:185: error: FailureMessagesTestCase.testAssertNotNil : XCTAssertNil failed - message
+// CHECK: test.swift:185: error: FailureMessagesTestCase.testAssertNotNil : XCTAssertNotNil failed - message
 // CHECK: Test Case 'FailureMessagesTestCase.testAssertNotNil' failed \(\d+\.\d+ seconds\).
 // CHECK: Test Case 'FailureMessagesTestCase.testAssertTrue' started.
 // CHECK: test.swift:189: error: FailureMessagesTestCase.testAssertTrue : XCTAssertTrue failed - message