diff --git a/TestFoundation/TestFileManager.swift b/TestFoundation/TestFileManager.swift
index ccf4625edf..e0c30ee92c 100644
--- a/TestFoundation/TestFileManager.swift
+++ b/TestFoundation/TestFileManager.swift
@@ -1321,81 +1321,81 @@ VIDEOS=StopgapVideos
         XCTAssertNil(NSHomeDirectoryForUser(""))
 
         XCTAssertThrowsError(try fm.contentsOfDirectory(atPath: "")) {
-            let code = CocoaError.Code(rawValue: ($0 as? NSError)!.code)
+            let code = CocoaError.Code(rawValue: $0.asNSError().code)
             XCTAssertEqual(code, .fileReadInvalidFileName)
         }
 
         XCTAssertNil(fm.enumerator(atPath: ""))
         XCTAssertNil(fm.subpaths(atPath: ""))
         XCTAssertThrowsError(try fm.subpathsOfDirectory(atPath: "")) {
-            let code = CocoaError.Code(rawValue: ($0 as? NSError)!.code)
+            let code = CocoaError.Code(rawValue: $0.asNSError().code)
             XCTAssertEqual(code, .fileReadInvalidFileName)
         }
 
         XCTAssertThrowsError(try fm.createDirectory(atPath: "", withIntermediateDirectories: true)) {
-            let code = CocoaError.Code(rawValue: ($0 as? NSError)!.code)
+            let code = CocoaError.Code(rawValue: $0.asNSError().code)
             XCTAssertEqual(code, .fileReadInvalidFileName)
         }
         XCTAssertFalse(fm.createFile(atPath: "", contents: Data()))
         XCTAssertThrowsError(try fm.removeItem(atPath: "")) {
-            let code = CocoaError.Code(rawValue: ($0 as? NSError)!.code)
+            let code = CocoaError.Code(rawValue: $0.asNSError().code)
             XCTAssertEqual(code, .fileReadInvalidFileName)
         }
 
         XCTAssertThrowsError(try fm.copyItem(atPath: "", toPath: "/tmp/t"))  {
-            let code = CocoaError.Code(rawValue: ($0 as? NSError)!.code)
+            let code = CocoaError.Code(rawValue: $0.asNSError().code)
             XCTAssertEqual(code, .fileReadInvalidFileName)
         }
         XCTAssertThrowsError(try fm.copyItem(atPath: "", toPath: ""))  {
-            let code = CocoaError.Code(rawValue: ($0 as? NSError)!.code)
+            let code = CocoaError.Code(rawValue: $0.asNSError().code)
             XCTAssertEqual(code, .fileReadInvalidFileName)
         }
         XCTAssertThrowsError(try fm.copyItem(atPath: "/tmp/t", toPath: "")) {
-            let code = CocoaError.Code(rawValue: ($0 as? NSError)!.code)
+            let code = CocoaError.Code(rawValue: $0.asNSError().code)
             XCTAssertEqual(code, .fileReadNoSuchFile)
         }
 
         XCTAssertThrowsError(try fm.moveItem(atPath: "", toPath: "/tmp/t")) {
-            let code = CocoaError.Code(rawValue: ($0 as? NSError)!.code)
+            let code = CocoaError.Code(rawValue: $0.asNSError().code)
             XCTAssertEqual(code, .fileReadInvalidFileName)
         }
         XCTAssertThrowsError(try fm.moveItem(atPath: "", toPath: "")) {
-            let code = CocoaError.Code(rawValue: ($0 as? NSError)!.code)
+            let code = CocoaError.Code(rawValue: $0.asNSError().code)
             XCTAssertEqual(code, .fileReadInvalidFileName)
         }
         XCTAssertThrowsError(try fm.moveItem(atPath: "/tmp/t", toPath: "")) {
-            let code = CocoaError.Code(rawValue: ($0 as? NSError)!.code)
+            let code = CocoaError.Code(rawValue: $0.asNSError().code)
             XCTAssertEqual(code, .fileReadInvalidFileName)
         }
 
         XCTAssertThrowsError(try fm.linkItem(atPath: "", toPath: "/tmp/t")) {
-            let code = CocoaError.Code(rawValue: ($0 as? NSError)!.code)
+            let code = CocoaError.Code(rawValue: $0.asNSError().code)
             XCTAssertEqual(code, .fileReadInvalidFileName)
         }
         XCTAssertThrowsError(try fm.linkItem(atPath: "", toPath: "")) {
-            let code = CocoaError.Code(rawValue: ($0 as? NSError)!.code)
+            let code = CocoaError.Code(rawValue: $0.asNSError().code)
             XCTAssertEqual(code, .fileReadInvalidFileName)
         }
         XCTAssertThrowsError(try fm.linkItem(atPath: "/tmp/t", toPath: "")) {
-            let code = CocoaError.Code(rawValue: ($0 as? NSError)!.code)
+            let code = CocoaError.Code(rawValue: $0.asNSError().code)
             XCTAssertEqual(code, .fileReadNoSuchFile)
         }
 
         XCTAssertThrowsError(try fm.createSymbolicLink(atPath: "", withDestinationPath: "")) {
-            let code = CocoaError.Code(rawValue: ($0 as? NSError)!.code)
+            let code = CocoaError.Code(rawValue: $0.asNSError().code)
             XCTAssertEqual(code, .fileReadInvalidFileName)
         }
         XCTAssertThrowsError(try fm.createSymbolicLink(atPath: "", withDestinationPath: "/tmp/t")) {
-            let code = CocoaError.Code(rawValue: ($0 as? NSError)!.code)
+            let code = CocoaError.Code(rawValue: $0.asNSError().code)
             XCTAssertEqual(code, .fileReadInvalidFileName)
         }
         XCTAssertThrowsError(try fm.createSymbolicLink(atPath: "/tmp/t", withDestinationPath: "")) {
-            let code = CocoaError.Code(rawValue: ($0 as? NSError)!.code)
+            let code = CocoaError.Code(rawValue: $0.asNSError().code)
             XCTAssertEqual(code, .fileReadInvalidFileName)
         }
 
         XCTAssertThrowsError(try fm.destinationOfSymbolicLink(atPath: "")) {
-            let code = CocoaError.Code(rawValue: ($0 as? NSError)!.code)
+            let code = CocoaError.Code(rawValue: $0.asNSError().code)
             XCTAssertEqual(code, .fileReadInvalidFileName)
         }
         XCTAssertFalse(fm.fileExists(atPath: ""))
@@ -1406,15 +1406,15 @@ VIDEOS=StopgapVideos
         XCTAssertTrue(fm.isDeletableFile(atPath: ""))
 
         XCTAssertThrowsError(try fm.attributesOfItem(atPath: "")) {
-            let code = CocoaError.Code(rawValue: ($0 as? NSError)!.code)
+            let code = CocoaError.Code(rawValue: $0.asNSError().code)
             XCTAssertEqual(code, .fileReadInvalidFileName)
         }
         XCTAssertThrowsError(try fm.attributesOfFileSystem(forPath: "")) {
-            let code = CocoaError.Code(rawValue: ($0 as? NSError)!.code)
+            let code = CocoaError.Code(rawValue: $0.asNSError().code)
             XCTAssertEqual(code, .fileReadInvalidFileName)
         }
         XCTAssertThrowsError(try fm.setAttributes([:], ofItemAtPath: "")) {
-            let code = CocoaError.Code(rawValue: ($0 as? NSError)!.code)
+            let code = CocoaError.Code(rawValue: $0.asNSError().code)
             XCTAssertEqual(code, .fileReadInvalidFileName)
         }
 
diff --git a/TestFoundation/TestNSError.swift b/TestFoundation/TestNSError.swift
index 317cf84590..f3886f7ab3 100644
--- a/TestFoundation/TestNSError.swift
+++ b/TestFoundation/TestNSError.swift
@@ -46,7 +46,7 @@ class TestNSError : XCTestCase {
         let nsdictionary = ["error": error] as NSDictionary
         let dictionary = nsdictionary as? Dictionary<String, Error>
         XCTAssertNotNil(dictionary)
-        XCTAssertEqual(error, dictionary?["error"] as? NSError)
+        XCTAssertEqual(error, dictionary?["error"]?.asNSError())
     }
 
     func test_CustomNSError_domain() {
@@ -94,14 +94,11 @@ class TestNSError : XCTestCase {
     func test_errorConvenience() {
         let error = CocoaError.error(.fileReadNoSuchFile, url: URL(fileURLWithPath: #file))
 
-        if let nsError = error as? NSError {
-            XCTAssertEqual(nsError._domain, NSCocoaErrorDomain)
-            XCTAssertEqual(nsError._code, CocoaError.fileReadNoSuchFile.rawValue)
-            if let filePath = nsError.userInfo[NSURLErrorKey] as? URL {
-                XCTAssertEqual(filePath, URL(fileURLWithPath: #file))
-            } else {
-                XCTFail()
-            }
+        let nsError = error.asNSError()
+        XCTAssertEqual(nsError.domain, NSCocoaErrorDomain)
+        XCTAssertEqual(nsError.code, CocoaError.fileReadNoSuchFile.rawValue)
+        if let filePath = nsError.userInfo[NSURLErrorKey] as? URL {
+            XCTAssertEqual(filePath, URL(fileURLWithPath: #file))
         } else {
             XCTFail()
         }
diff --git a/TestFoundation/TestURL.swift b/TestFoundation/TestURL.swift
index f6ce2bace5..fba62f9a4f 100644
--- a/TestFoundation/TestURL.swift
+++ b/TestFoundation/TestURL.swift
@@ -297,7 +297,7 @@ class TestURL : XCTestCase {
           try FileManager.default.removeItem(atPath: gFileDoesNotExistPath)
         } catch {
           // The error code is a CocoaError
-          if (error as? NSError)?.code != CocoaError.fileNoSuchFile.rawValue {
+          if error.asNSError().code != CocoaError.fileNoSuchFile.rawValue {
             return false
           }
         }
@@ -306,7 +306,7 @@ class TestURL : XCTestCase {
           try FileManager.default.createDirectory(atPath: gDirectoryExistsPath, withIntermediateDirectories: false)
         } catch {
             // The error code is a CocoaError
-            if (error as? NSError)?.code != CocoaError.fileWriteFileExists.rawValue {
+            if error.asNSError().code != CocoaError.fileWriteFileExists.rawValue {
                 return false
             }
         }
@@ -315,7 +315,7 @@ class TestURL : XCTestCase {
           try FileManager.default.removeItem(atPath: gDirectoryDoesNotExistPath)
         } catch {
             // The error code is a CocoaError
-            if (error as? NSError)?.code != CocoaError.fileNoSuchFile.rawValue {
+            if error.asNSError().code != CocoaError.fileNoSuchFile.rawValue {
                 return false
             }
         }
@@ -624,11 +624,8 @@ class TestURL : XCTestCase {
                 assertRelevantValuesAreEqual(in: newValues)
             }
         } catch {
-            if let error = error as? NSError {
-                print("error: \(error.description) - \(error.userInfo)")
-            } else {
-                print("error: \(error)")
-            }
+            let error = error.asNSError()
+            print("error: \(error.description) - \(error.userInfo)")
             throw error
         }
     }
diff --git a/TestFoundation/Utilities.swift b/TestFoundation/Utilities.swift
index 7cf325347a..a3cbf1e406 100644
--- a/TestFoundation/Utilities.swift
+++ b/TestFoundation/Utilities.swift
@@ -133,6 +133,17 @@ func _checkHashing<Source: Hashable, Target: Hashable, S: Sequence>(
     }
 }
 
+extension Error {
+    func asNSError() -> NSError {
+        // The cast will never fail, and this will create a warning during
+        // compilation, but since it is SwiftFoundation.NSError (and not ObjC
+        // NSError) the macOS build cannot detect that and might fail indicating
+        // some catch is not exhaustive. This avoid the compilation problem,
+        // but centralizes all the warnings in only this point.
+        return (self as? NSError)!
+    }
+}
+
 enum TestError: Error {
     case unexpectedNil
 }