neverCalled top-level property

Null Function([Object, Object, Object, Object, Object, Object, Object, Object, Object, Object ]) neverCalled

Returns a function that causes the test to fail if it's called.

This can safely be passed in place of any callback that takes ten or fewer positional parameters. For example:

// Asserts that the stream never emits an event.
stream.listen(neverCalled);

This also ensures that the test doesn't complete until a call to pumpEventQueue finishes, so that the callback has a chance to be called.

Implementation 

Null Function(
    [Object,
    Object,
    Object,
    Object,
    Object,
    Object,
    Object,
    Object,
    Object,
    Object]) get neverCalled {
  // Make sure the test stays alive long enough to call the function if it's
  // going to.
  expect(pumpEventQueue(), completes);

  var zone = Zone.current;
  return (
      [a1 = placeholder,
      a2 = placeholder,
      a3 = placeholder,
      a4 = placeholder,
      a5 = placeholder,
      a6 = placeholder,
      a7 = placeholder,
      a8 = placeholder,
      a9 = placeholder,
      a10 = placeholder]) {
    var arguments = [a1, a2, a3, a4, a5, a6, a7, a8, a9, a10]
        .where((argument) => argument != placeholder)
        .toList();

    zone.handleUncaughtError(
        TestFailure(
            "Callback should never have been called, but it was called with" +
                (arguments.isEmpty
                    ? " no arguments."
                    : ":\n${bullet(arguments.map(prettyPrint))}")),
        zone.run(() => Chain.current()));
    return null;
  };
}