Language/Statements/Try/exception_handler_t02.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 A try statement try s1 on − catch1 ... on − catchn finally sf
/// defines an exception handler h that executes as follows:
///   The on-catch clauses are examined in order, starting with catch1, until
/// either an on-catch clause that matches the current exception is found,
/// or the list of on-catch clauses has been exhausted. If an on-catch clause
/// on−catchk is found, then pk1 is bound to the current exception, pk2, if
/// declared, is bound to the active stack trace, and then catchk is executed.
/// If no on-catch clause is found, the finally clause is executed. Then,
/// execution resumes at the end of the try statement.
///   A finally clause finally s defines an exception handler h that executes
/// as follows:
///   Let r be the current return value. Then the current return value becomes
/// undefined. Any open streams associated with any asynchronous for loops and
/// yield-each statements executing within the dynamic scope of h are canceled,
/// in the order of their nesting, innermost first.
///   Streams left open by for loops that were escaped for whatever reason would
/// be canceled at function termination, but it is best to cancel them as soon as
/// possible.
///   Then the finally clause is executed. Let m be the immediately enclosing
/// function. If r is defined then the current return value is set to r and then:
///  • if there is a dynamically enclosing error handler g defined by a finally
///    clause in m, control is transferred to g.
///  • Otherwise m terminates.
///  Otherwise, execution resumes at the end of the try statement.
/// @description Checks that the finally clause is executed regardless of whether
/// or not a matching catch clause was found and whether or not there were any to
/// begin with. Implicitly checks that execution resumes at the end of the try
/// statement or is transferred to the nearest dynamically enclosing exception
/// handler depending on whether or not the current exception was made undefined
/// by an executed catch clause.
/// @author rodionov

import '../../../Utils/expect.dart';


void main() {
  bool isFinallyExecuted = false;
  var ex = "fail";
  try {
    try {
      throw ex;
    } on int catch (i) {
    } on bool catch (b) {
    } finally {
      isFinallyExecuted = true;
    }
    Expect.fail("This code shouldn't be executed");
  } on String catch (s) {
    Expect.equals(ex, s);
  }
  Expect.equals(true, isFinallyExecuted);

  isFinallyExecuted = false;
  try {
    throw ex;
  } on int catch (i) {
  } on String catch (s) {
  } on bool catch (b) {
  } finally {
    isFinallyExecuted = true;
  }
  Expect.equals(true, isFinallyExecuted);

  isFinallyExecuted = false;
  try {
    try {
      throw ex;
    } finally {
      isFinallyExecuted = true;
    }
    Expect.fail("This code shouldn't be executed");
  } on String catch (s) {
    Expect.equals(ex, s);
  }
  Expect.equals(true, isFinallyExecuted);
}