       }
       XCTFail()
     } catch {
-      XCTAssertEqual((error as NSError).code, -1)
+      XCTAssertEqual(Failure(), error as? Failure)
     }
     XCTAssertEqual(actual, expected)
   }

//
// This source file is part of the Swift Async Algorithms open source project
//
// Copyright (c) 2021 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information

    let expected = [1, 2, 3]
    var actual = [Int]()
    let sequence = source.async.removeDuplicates() { prev, next in
      let next = try throwOn(-1, next)
      return prev == next
    }

