Merge pull request #166 from briancroom/discardable-result

Add @discardableResult annotation to applicable public API methods.

Author: briancroom

Sources/XCTest/Public/XCTestCase+Asynchronous.swift

@@ -39,7 +39,7 @@ public extension XCTestCase {
     ///   between these environments. To ensure compatibility of tests between
     ///   swift-corelibs-xctest and Apple XCTest, it is not recommended to pass
     ///   explicit values for `file` and `line`.
-    func expectation(description: String, file: StaticString = #file, line: UInt = #line) -> XCTestExpectation {
+    @discardableResult func expectation(description: String, file: StaticString = #file, line: UInt = #line) -> XCTestExpectation {
         let expectation = XCTestExpectation(
             description: description,
             file: file,
@@ -164,7 +164,7 @@ public extension XCTestCase {
     ///   notification is observed. It will not be invoked on timeout. Use the
     ///   handler to further investigate if the notification fulfills the
     ///   expectation.
-    func expectation(forNotification notificationName: String, object objectToObserve: AnyObject?, handler: XCNotificationExpectationHandler? = nil) -> XCTestExpectation {
+    @discardableResult func expectation(forNotification notificationName: String, object objectToObserve: AnyObject?, handler: XCNotificationExpectationHandler? = nil) -> XCTestExpectation {
         let objectDescription = objectToObserve == nil ? "any object" : "\(objectToObserve!)"
         let expectation = self.expectation(description: "Expect notification '\(notificationName)' from " + objectDescription)
         // Start observing the notification with specified name and object.
@@ -226,7 +226,7 @@ public extension XCTestCase {
     ///   first successful evaluation will fulfill the expectation. If provided,
     ///   the handler can override that behavior which leaves the caller
     ///   responsible for fulfilling the expectation.
-    func expectation(for predicate: NSPredicate, evaluatedWith object: AnyObject, file: StaticString = #file, line: UInt = #line, handler: XCPredicateExpectationHandler? = nil) -> XCTestExpectation {
+    @discardableResult func expectation(for predicate: NSPredicate, evaluatedWith object: AnyObject, file: StaticString = #file, line: UInt = #line, handler: XCPredicateExpectationHandler? = nil) -> XCTestExpectation {
         let expectation = XCPredicateExpectation(
             predicate: predicate,
             object: object,