Add a string_scanner package.

pkg/string_scanner/test/string_scanner_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.string_scanner_test;
+
+import 'package:string_scanner/string_scanner.dart';
+import 'package:unittest/unittest.dart';
+
+void main() {
+  group('with an empty string', () {
+    var scanner;
+    setUp(() {
+      scanner = new StringScanner('');
+    });
+
+    test('is done', () {
+      expect(scanner.isDone, isTrue);
+      expect(scanner.expectDone, isNot(throwsFormatException));
+    });
+
+    test('rest is empty', () {
+      expect(scanner.rest, isEmpty);
+    });
+
+    test('lastMatch is null', () {
+      expect(scanner.lastMatch, isNull);
+    });
+
+    test('position is zero', () {
+      expect(scanner.position, equals(0));
+    });
+
+    test("scan returns false and doesn't change the state", () {
+      expect(scanner.scan(new RegExp('.')), isFalse);
+      expect(scanner.lastMatch, isNull);
+      expect(scanner.position, equals(0));
+    });
+
+    test("expect throws a FormatException and doesn't change the state", () {
+      expect(() => scanner.expect(new RegExp('.')), throwsFormatException);
+      expect(scanner.lastMatch, isNull);
+      expect(scanner.position, equals(0));
+    });
+
+    test("matches returns false and doesn't change the state", () {
+      expect(scanner.matches(new RegExp('.')), isFalse);
+      expect(scanner.lastMatch, isNull);
+      expect(scanner.position, equals(0));
+    });
+
+    test('setting position to 1 throws an ArgumentError', () {
+      expect(() {
+        scanner.position = 1;
+      }, throwsArgumentError);
+    });
+
+    test('setting position to -1 throws an ArgumentError', () {
+      expect(() {
+        scanner.position = -1;
+      }, throwsArgumentError);
+    });
+  });
+
+  group('at the beginning of a string', () {
+    var scanner;
+    setUp(() {
+      scanner = new StringScanner('foo bar');
+    });
+
+    test('is not done', () {
+      expect(scanner.isDone, isFalse);
+      expect(scanner.expectDone, throwsFormatException);
+    });
+
+    test('rest is the whole string', () {
+      expect(scanner.rest, equals('foo bar'));
+    });
+
+    test('lastMatch is null', () {
+      expect(scanner.lastMatch, isNull);
+    });
+
+    test('position is zero', () {
+      expect(scanner.position, equals(0));
+    });
+
+    test("a matching scan returns true and changes the state", () {
+      expect(scanner.scan(new RegExp('f(..)')), isTrue);
+      expect(scanner.lastMatch[1], equals('oo'));
+      expect(scanner.position, equals(3));
+      expect(scanner.rest, equals(' bar'));
+    });
+
+    test("a non-matching scan returns false and sets lastMatch to null", () {
+      expect(scanner.matches(new RegExp('f(..)')), isTrue);
+      expect(scanner.lastMatch, isNotNull);
+
+      expect(scanner.scan(new RegExp('b(..)')), isFalse);
+      expect(scanner.lastMatch, isNull);
+      expect(scanner.position, equals(0));
+      expect(scanner.rest, equals('foo bar'));
+    });
+
+    test("a matching expect changes the state", () {
+      scanner.expect(new RegExp('f(..)'));
+      expect(scanner.lastMatch[1], equals('oo'));
+      expect(scanner.position, equals(3));
+      expect(scanner.rest, equals(' bar'));
+    });
+
+    test("a non-matching expect throws a FormatException and sets lastMatch to "
+        "null", () {
+      expect(scanner.matches(new RegExp('f(..)')), isTrue);
+      expect(scanner.lastMatch, isNotNull);
+
+      expect(() => scanner.expect(new RegExp('b(..)')), throwsFormatException);
+      expect(scanner.lastMatch, isNull);
+      expect(scanner.position, equals(0));
+      expect(scanner.rest, equals('foo bar'));
+    });
+
+    test("a matching matches returns true and only changes lastMatch", () {
+      expect(scanner.matches(new RegExp('f(..)')), isTrue);
+      expect(scanner.lastMatch[1], equals('oo'));
+      expect(scanner.position, equals(0));
+      expect(scanner.rest, equals('foo bar'));
+    });
+
+    test("a non-matching matches returns false and doesn't change the state",
+        () {
+      expect(scanner.matches(new RegExp('b(..)')), isFalse);
+      expect(scanner.lastMatch, isNull);
+      expect(scanner.position, equals(0));
+      expect(scanner.rest, equals('foo bar'));
+    });
+
+    test('setting position to 1 moves the cursor forward', () {
+      scanner.position = 1;
+      expect(scanner.position, equals(1));
+      expect(scanner.rest, equals('oo bar'));
+
+      expect(scanner.scan(new RegExp('oo.')), isTrue);
+      expect(scanner.lastMatch[0], equals('oo '));
+      expect(scanner.position, equals(4));
+      expect(scanner.rest, equals('bar'));
+    });
+
+    test('setting position beyond the string throws an ArgumentError', () {
+      expect(() {
+        scanner.position = 8;
+      }, throwsArgumentError);
+    });
+
+    test('setting position to -1 throws an ArgumentError', () {
+      expect(() {
+        scanner.position = -1;
+      }, throwsArgumentError);
+    });
+
+    test('scan accepts any Pattern', () {
+      expect(scanner.scan('foo'), isTrue);
+      expect(scanner.lastMatch[0], equals('foo'));
+      expect(scanner.position, equals(3));
+      expect(scanner.rest, equals(' bar'));
+    });
+
+    test('scans multiple times', () {
+      expect(scanner.scan(new RegExp('f(..)')), isTrue);
+      expect(scanner.lastMatch[1], equals('oo'));
+      expect(scanner.position, equals(3));
+      expect(scanner.rest, equals(' bar'));
+
+      expect(scanner.scan(new RegExp(' b(..)')), isTrue);
+      expect(scanner.lastMatch[1], equals('ar'));
+      expect(scanner.position, equals(7));
+      expect(scanner.rest, equals(''));
+      expect(scanner.isDone, isTrue);
+      expect(scanner.expectDone, isNot(throwsFormatException));
+    });
+  });
+
+  group('at the end of a string', () {
+    var scanner;
+    setUp(() {
+      scanner = new StringScanner('foo bar');
+      expect(scanner.scan('foo bar'), isTrue);
+    });
+
+    test('is done', () {
+      expect(scanner.isDone, isTrue);
+      expect(scanner.expectDone, isNot(throwsFormatException));
+    });
+
+    test('rest is empty', () {
+      expect(scanner.rest, isEmpty);
+    });
+
+    test('position is zero', () {
+      expect(scanner.position, equals(7));
+    });
+
+    test("scan returns false and sets lastMatch to null", () {
+      expect(scanner.scan(new RegExp('.')), isFalse);
+      expect(scanner.lastMatch, isNull);
+      expect(scanner.position, equals(7));
+    });
+
+    test("expect throws a FormatException and sets lastMatch to null", () {
+      expect(() => scanner.expect(new RegExp('.')), throwsFormatException);
+      expect(scanner.lastMatch, isNull);
+      expect(scanner.position, equals(7));
+    });
+
+    test("matches returns false sets lastMatch to null", () {
+      expect(scanner.matches(new RegExp('.')), isFalse);
+      expect(scanner.lastMatch, isNull);
+      expect(scanner.position, equals(7));
+    });
+
+    test('setting position to 1 moves the cursor backward', () {
+      scanner.position = 1;
+      expect(scanner.position, equals(1));
+      expect(scanner.rest, equals('oo bar'));
+
+      expect(scanner.scan(new RegExp('oo.')), isTrue);
+      expect(scanner.lastMatch[0], equals('oo '));
+      expect(scanner.position, equals(4));
+      expect(scanner.rest, equals('bar'));
+    });
+
+    test('setting position beyond the string throws an ArgumentError', () {
+      expect(() {
+        scanner.position = 8;
+      }, throwsArgumentError);
+    });
+
+    test('setting position to -1 throws an ArgumentError', () {
+      expect(() {
+        scanner.position = -1;
+      }, throwsArgumentError);
+    });
+  });
+
+  group('a scanner constructed with a custom position', () {
+    test('starts scanning from that position', () {
+      var scanner = new StringScanner('foo bar', position: 1);
+      expect(scanner.position, equals(1));
+      expect(scanner.rest, equals('oo bar'));
+
+      expect(scanner.scan(new RegExp('oo.')), isTrue);
+      expect(scanner.lastMatch[0], equals('oo '));
+      expect(scanner.position, equals(4));
+      expect(scanner.rest, equals('bar'));
+    });
+
+    test('throws an ArgumentError if the position is -1', () {
+      expect(() => new StringScanner('foo bar', position: -1),
+          throwsArgumentError);
+    });
+
+    test('throws an ArgumentError if the position is beyond the string', () {
+      expect(() => new StringScanner('foo bar', position: 8),
+          throwsArgumentError);
+    });
+  });
+}