Convert shelf to use the string_scanner package.

pkg/string_scanner/test/error_test.dart

+// Copyright (c) 2014, 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 string_scanner.error_test;
+
+import 'package:string_scanner/string_scanner.dart';
+import 'package:unittest/unittest.dart';
+
+import 'utils.dart';
+
+void main() {
+  test('defaults to the last match', () {
+    var scanner = new StringScanner('foo bar baz');
+    scanner.expect('foo ');
+    scanner.expect('bar');
+    expect(() => scanner.error('oh no!'), throwsFormattedError('''
+Error on line 1, column 5: oh no!
+foo bar baz
+    ^^^'''));
+  });
+
+  group("with match", () {
+    test('supports an earlier match', () {
+      var scanner = new StringScanner('foo bar baz');
+      scanner.expect('foo ');
+      var match = scanner.lastMatch;
+      scanner.expect('bar');
+      expect(() => scanner.error('oh no!', match: match),
+          throwsFormattedError('''
+Error on line 1, column 1: oh no!
+foo bar baz
+^^^^'''));
+    });
+
+    test('supports a match on a previous line', () {
+      var scanner = new StringScanner('foo bar baz\ndo re mi\nearth fire water');
+      scanner.expect('foo bar baz\ndo ');
+      scanner.expect('re');
+      var match = scanner.lastMatch;
+      scanner.expect(' mi\nearth ');
+      expect(() => scanner.error('oh no!', match: match),
+          throwsFormattedError('''
+Error on line 2, column 4: oh no!
+do re mi
+   ^^'''));
+    });
+
+    test('supports a multiline match', () {
+      var scanner = new StringScanner('foo bar baz\ndo re mi\nearth fire water');
+      scanner.expect('foo bar ');
+      scanner.expect('baz\ndo');
+      var match = scanner.lastMatch;
+      scanner.expect(' re mi');
+      expect(() => scanner.error('oh no!', match: match),
+          throwsFormattedError('''
+Error on line 1, column 9: oh no!
+foo bar baz
+        ^^^'''));
+    });
+
+    test('supports a match after position', () {
+      var scanner = new StringScanner('foo bar baz');
+      scanner.expect('foo ');
+      scanner.expect('bar');
+      var match = scanner.lastMatch;
+      scanner.position = 0;
+      expect(() => scanner.error('oh no!', match: match),
+          throwsFormattedError('''
+Error on line 1, column 5: oh no!
+foo bar baz
+    ^^^'''));
+    });
+  });
+
+  group("with position and/or length", () {
+    test('defaults to length 1', () {
+      var scanner = new StringScanner('foo bar baz');
+      scanner.expect('foo ');
+      expect(() => scanner.error('oh no!', position: 1),
+          throwsFormattedError('''
+Error on line 1, column 2: oh no!
+foo bar baz
+ ^'''));
+    });
+
+    test('defaults to the current position', () {
+      var scanner = new StringScanner('foo bar baz');
+      scanner.expect('foo ');
+      expect(() => scanner.error('oh no!', length: 3),
+          throwsFormattedError('''
+Error on line 1, column 5: oh no!
+foo bar baz
+    ^^^'''));
+    });
+
+    test('supports an earlier position', () {
+      var scanner = new StringScanner('foo bar baz');
+      scanner.expect('foo ');
+      expect(() => scanner.error('oh no!', position: 1, length: 2),
+          throwsFormattedError('''
+Error on line 1, column 2: oh no!
+foo bar baz
+ ^^'''));
+    });
+
+    test('supports a position on a previous line', () {
+      var scanner = new StringScanner('foo bar baz\ndo re mi\nearth fire water');
+      scanner.expect('foo bar baz\ndo re mi\nearth');
+      expect(() => scanner.error('oh no!', position: 15, length: 2),
+          throwsFormattedError('''
+Error on line 2, column 4: oh no!
+do re mi
+   ^^'''));
+    });
+
+    test('supports a multiline length', () {
+      var scanner = new StringScanner('foo bar baz\ndo re mi\nearth fire water');
+      scanner.expect('foo bar baz\ndo re mi\nearth');
+      expect(() => scanner.error('oh no!', position: 8, length: 8),
+          throwsFormattedError('''
+Error on line 1, column 9: oh no!
+foo bar baz
+        ^^^'''));
+    });
+
+    test('supports a position after the current one', () {
+      var scanner = new StringScanner('foo bar baz');
+      expect(() => scanner.error('oh no!', position: 4, length: 3),
+          throwsFormattedError('''
+Error on line 1, column 5: oh no!
+foo bar baz
+    ^^^'''));
+    });
+  });
+
+  group("argument errors", () {
+    var scanner;
+    setUp(() {
+      scanner = new StringScanner('foo bar baz');
+      scanner.scan('foo');
+    });
+
+    test("if match is passed with position", () {
+      expect(
+          () => scanner.error("oh no!", match: scanner.lastMatch, position: 1),
+          throwsArgumentError);
+    });
+
+    test("if match is passed with length", () {
+      expect(
+          () => scanner.error("oh no!", match: scanner.lastMatch, length: 1),
+          throwsArgumentError);
+    });
+
+    test("if position is negative", () {
+      expect(() => scanner.error("oh no!", position: -1), throwsArgumentError);
+    });
+
+    test("if position is outside the string", () {
+      expect(() => scanner.error("oh no!", position: 100), throwsArgumentError);
+    });
+
+    test("if length is zero", () {
+      expect(() => scanner.error("oh no!", length: 0), throwsArgumentError);
+    });
+  });
+}