LibTest/async/Future/catchError_A07_t01.dart

// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

/// @assertion Future catchError(Function onError, {bool test(Object error)})
///    If this future completes with an error, then test is first called with
/// the error value.
///    If test returns false, the exception is not handled by this catchError,
/// and the returned future completes with the same error and stack trace as
/// this future.
///    If test returns true, onError is called with the error and possibly stack
/// trace, and the returned future is completed with the result of this call in
/// exactly the same way as for then's onError.
///    If test is omitted, it defaults to a function that always returns true.
/// The test function should not throw, but if it does, it is handled as if
/// the onError function had thrown.
/// @description Checks that it is a runtime error if [onError] callback has more
/// than two parameters.
/// @author ilya

import "dart:async";
import "../../../Utils/expect.dart";

f() {
    // With sound null safety, registering incompatible callback is synchronous error,
    // future ends up with no error handler that will lead to async exception
    // with error object equal to 1.
    Expect.throws(() => new Future.error(1).catchError((x, y, z) {}));
}

main() {
  asyncStart();
  runZoned(f, onError: (e) {
    Expect.equals(1, e);
    asyncEnd();
  });
}