Add the content of the package.

test/evaluate_test.dart

+// Copyright (c) 2016, 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.
+
+import 'package:test/test.dart';
+
+import 'package:boolean_selector/boolean_selector.dart';
+
+void main() {
+  group("operator:", () {
+    test("conditional", () {
+      _expectEval("true ? true : false", true);
+      _expectEval("true ? false : true", false);
+      _expectEval("false ? true : false", false);
+      _expectEval("false ? false : true", true);
+    });
+
+    test("or", () {
+      _expectEval("true || true", true);
+      _expectEval("true || false", true);
+      _expectEval("false || true", true);
+      _expectEval("false || false", false);
+    });
+
+    test("and", () {
+      _expectEval("true && true", true);
+      _expectEval("true && false", false);
+      _expectEval("false && true", false);
+      _expectEval("false && false", false);
+    });
+
+    test("not", () {
+      _expectEval("!true", false);
+      _expectEval("!false", true);
+    });
+  });
+
+  test("with a semantics function", () {
+    _expectEval("foo", false, semantics: (variable) => variable.contains("a"));
+    _expectEval("bar", true, semantics: (variable) => variable.contains("a"));
+    _expectEval("baz", true, semantics: (variable) => variable.contains("a"));
+  });
+}
+
+/// Asserts that [expression] evaluates to [result] against [semantics].
+///
+/// By default, "true" is true and all other variables are "false".
+void _expectEval(String expression, bool result, {semantics}) {
+  var reason = 
+  expect(_eval(expression, semantics: semantics), equals(result),
+      reason: 'Expected "$expression" to evaluate to $result.');
+}
+
+/// Returns the result of evaluating [expression] on [semantics].
+///
+/// By default, "true" is true and all other variables are "false".
+bool _eval(String expression, {semantics}) {
+  var selector = new BooleanSelector.parse(expression);
+  return selector.evaluate(semantics ?? ["true"]);
+}