Add logging to .unwrapped() and move it to Utilities.

Author: millenomi

TestFoundation/TestNSCalendar.swift

@@ -7,21 +7,6 @@
 // See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 //
 
-enum TestError: Error {
-    case unexpectedNil
-}
-
-extension Optional {
-    func unwrapped() throws -> Wrapped {
-        if let x = self {
-            return x
-        } else {
-            XCTFail()
-            throw TestError.unexpectedNil
-        }
-    }
-}
-
 class TestNSCalendar: XCTestCase {
     func test_initWithCalendarIdentifier() {
         var calMaybe = NSCalendar(calendarIdentifier: NSCalendar.Identifier("Not a calendar"))

TestFoundation/Utilities.swift

@@ -113,3 +113,18 @@ func _checkHashing<Source: Hashable, Target: Hashable, S: Sequence>(
             file: file, line: line)
     }
 }
+
+enum TestError: Error {
+    case unexpectedNil
+}
+
+extension Optional {
+    func unwrapped(_ fn: String = #function, file: StaticString = #file, line: UInt = #line) throws -> Wrapped {
+        if let x = self {
+            return x
+        } else {
+            XCTFail("Tried to invoke .unwrapped() on nil in \(file):\(line):\(fn)")
+            throw TestError.unexpectedNil
+        }
+    }
+}