Add extra information to FormatException.

tests/corelib/format_exception_test.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.
+
+library format_exception_test;
+import "package:expect/expect.dart";
+
+test(exn, message, source, position, toString) {
+  Expect.equals(message, exn.message);
+  Expect.equals(source, exn.source);
+  Expect.equals(position, exn.position);
+  Expect.equals(toString, exn.toString());
+}
+
+main() {
+  var e;
+  e = new FormatException();
+  test(e, "", null, null, "FormatException");
+  e = new FormatException("");
+  test(e, "", null, null, "FormatException");
+  e = new FormatException(null);
+  test(e, null, null, null, "FormatException");
+
+  e = new FormatException("message");
+  test(e, "message", null, null, "FormatException: message");
+
+  e = new FormatException("message", "source");
+  test(e, "message", "source", null, "FormatException: message\nsource");
+
+  e = new FormatException("message", "source" * 25);
+  test(e, "message", "source" * 25, null, "FormatException: message\n" +
+                                          "source" * 12 + "sou...");
+  e = new FormatException("message", "source" * 25);
+  test(e, "message", "source" * 25, null, "FormatException: message\n" +
+                                          "source" * 12 + "sou...");
+  e = new FormatException("message", "s1\nsource\ns2");
+  test(e, "message", "s1\nsource\ns2", null, "FormatException: message\n" +
+                                             "s1\nsource\ns2");
+
+  var o = new Object();
+  e = new FormatException("message", o, 10);
+  test(e, "message", o, 10, "FormatException: message (at position 10)");
+
+  e = new FormatException("message", "source", 3);
+  test(e, "message", "source", 3,
+       "FormatException: message (at character 4)\nsource\n   ^\n");
+
+  e = new FormatException("message", "s1\nsource\ns2", 6);
+  test(e, "message", "s1\nsource\ns2", 6,
+       "FormatException: message (at line 2, character 4)\nsource\n   ^\n");
+
+  var longline = "watermelon cantaloupe " * 8 + "watermelon";  // Length > 160.
+  var longsource = (longline + "\n") * 25;
+  var line10 = (longline.length + 1) * 9;
+  e = new FormatException("message", longsource, line10);
+  test(e, "message", longsource, line10,
+       "FormatException: message (at line 10, character 1)\n"
+       "${longline.substring(0, 75)}...\n^\n");
+
+  e = new FormatException("message", longsource, line10 - 1);
+  test(e, "message", longsource, line10 - 1,
+       "FormatException: message (at line 9, "
+       "character ${longline.length + 1})\n"
+       "...${longline.substring(longline.length - 75)}\n"
+       "${' ' * 78}^\n");
+
+  var half = longline.length ~/ 2;
+  e = new FormatException("message", longsource, line10 + half);
+  test(e, "message", longsource, line10 + half,
+       "FormatException: message (at line 10, character ${half + 1})\n"
+       "...${longline.substring(half - 36, half + 36)}...\n"
+       "${' ' * 39}^\n");
+}