Language/Libraries_and_Scripts/Imports/deferred_import_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 The current library is the library currently being compiled. The
/// import modifies the import namespace of the current library in a manner that
/// is determined by the imported library and by the optional elements of the
/// import.
/// . . .
/// Let I be an import directive that refers to a URI via the string s1.
/// Evaluation of I proceeds as follows:
///
/// If I is a deferred import, no evaluation takes place. Instead, a mapping of
/// the name of the prefix, p to a deferred prefix object is added to the scope
/// of the current library L. The deferred prefix object has the following
/// methods:
/// • loadLibrary. This method returns a future f. When called, the method
///   causes an immediate import I to be executed at some future time, where
///   I is is derived from I by eliding the word deferred and adding a hide
///   loadLibrary combinator clause. When I executes without error, f completes
///   successfully. If I executes without error, we say that the call to
///   loadLibrary has succeeded, otherwise we say the call has failed.
/// • For every top level function f named id in the imported library B, a
///   corresponding method named id with the same signature as f. Calling
///   the method results in a runtime error.
/// • For every top level getter g named id in B, a corresponding getter named
///   id with the same signature as g. Calling the method results in a runtime
///    error.
/// • For every top level setter s named id in B, a corresponding setter named
///   id with the same signature as s. Calling the method results in a runtime
///   error.
/// • For every type T named id in B, a corresponding getter named id with
///   return type Type. Calling the method results in a runtime error.
/// . . .
/// After a call succeeds, the name p is mapped to a non-deferred prefix object
/// as described below. In addition, the prefix object also supports the
/// loadLibrary method, and so it is possible to call loadLibrary again. If
/// a call fails, nothing happens, and one again has the option to call
/// loadLibrary again. Whether a repeated call to loadLibrary succeeds will
/// vary as described below.
/// The effect of a repeated call to p.loadLibrary is as follows:
/// • If another call to p.loadLibrary has already succeeded, the repeated call
///   also succeeds. Otherwise,
/// • If another call to to p.loadLibrary has failed:
///   – If the failure is due to a compilation error, the repeated call fails
///     for the same reason.
///   – If the failure is due to other causes, the repeated call behaves as if
///     no previous call had been made.
/// In other words, one can retry a deferred load after a network failure or
/// because a file is absent, but once one finds some content and loads it, one
/// can no longer reload.
///
/// @description Checks that a deferred prefix object has a method loadLibrary,
/// returning a future f, and for every top-level declaration in the imported
/// library a corresponding declaration with the same name in the current
/// library. Calling the imported name results in a runtime error.
/// @Issue 33118
/// @issue 42491
/// @author ngl@unipro.ru

import "dart:async";
import "../../../Utils/expect.dart";
import "static_type_lib.dart" deferred as p;

main() {

  Expect.throws(() { p.someFunc(); }, (e) => e is NoSuchMethodError);
  Expect.throws(() { p.someGetter; }, (e) => e is NoSuchMethodError);
  Expect.throws(() { p.someSetter = 2; }, (e) => e is NoSuchMethodError);
  Expect.throws(() { p.Func; }, (e) => e is NoSuchMethodError);

  Expect.isTrue(p.loadLibrary() is Future);
  Expect.runtimeIsType<Future>(p.loadLibrary());
}