Replace the configuration map with a typed object.

tests/standalone/status_expression_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 StatusExpressionTest;
+import "package:expect/expect.dart";
 
-import "package:expect/expect.dart";
+import "../../tools/testing/dart/environment.dart";
 import "../../tools/testing/dart/status_expression.dart";
 
+class TestEnvironment implements Environment {
+  final Map<String, String> _values;
+
+  TestEnvironment(this._values);
+
+  /// Looks up the value of the variable with [name].
+  String lookUp(String name) => _values[name];
+
+  operator []=(String key, String value) => _values[key] = value;
+}
+
 main() {
   testExpression();
   testSyntaxError();
   testBoolean();
   testNotEqual();
 }
 
 void testExpression() {
   var expression = Expression
       .parse(r" $mode == debug && ($arch == chromium || $arch == dartc) ");
   Expect.equals(
       r"(($mode == debug) && (($arch == chromium) || ($arch == dartc)))",
       expression.toString());
 
   // Test BooleanExpression.evaluate().
-  var environment = <String, dynamic>{"arch": "dartc", "mode": "debug"};
+  var environment = new TestEnvironment({"arch": "dartc", "mode": "debug"});
 
   Expect.isTrue(expression.evaluate(environment));
   environment["mode"] = "release";
   Expect.isFalse(expression.evaluate(environment));
   environment["arch"] = "ia32";
   Expect.isFalse(expression.evaluate(environment));
   environment["mode"] = "debug";
   Expect.isFalse(expression.evaluate(environment));
   environment["arch"] = "chromium";
   Expect.isTrue(expression.evaluate(environment));
 }
 
 void testSyntaxError() {
   var input = r"($arch == (-dartc || $arch == chromium) && $mode == release";
   Expect.throws(() {
     Expression.parse(input);
   }, (e) => e.toString() == "FormatException: Syntax error in '$input'");
 }
 
 void testBoolean() {
   var expression =
       Expression.parse(r"  $arch == ia32 && $checked || $mode == release    ");
   Expect.equals(r"((($arch == ia32) && (bool $checked)) || ($mode == release))",
       expression.toString());
 
   // Test BooleanExpression.evaluate().
-  var environment = <String, dynamic>{
-    "arch": "ia32",
-    "checked": true,
-    "mode": "debug"
-  };
+  var environment =
+      new TestEnvironment({"arch": "ia32", "checked": "true", "mode": "debug"});
 
   Expect.isTrue(expression.evaluate(environment));
   environment["mode"] = "release";
   Expect.isTrue(expression.evaluate(environment));
   environment["checked"] = false;
   Expect.isTrue(expression.evaluate(environment));
   environment["mode"] = "debug";
   Expect.isFalse(expression.evaluate(environment));
   environment["arch"] = "arm";
   Expect.isFalse(expression.evaluate(environment));
   environment["checked"] = true;
   Expect.isFalse(expression.evaluate(environment));
 }
 
 void testNotEqual() {
   // Test the != operator.
   var expression = Expression.parse(r"$compiler == dart2js && $runtime != ie9");
   Expect.equals(
       r"(($compiler == dart2js) && ($runtime != ie9))", expression.toString());
 
   // Test BooleanExpression.evaluate().
-  var environment = <String, dynamic>{
+  var environment = new TestEnvironment({
     "compiler": "none",
     "runtime": "ie9",
-  };
+  });
 
   Expect.isFalse(expression.evaluate(environment));
   environment["runtime"] = "chrome";
   Expect.isFalse(expression.evaluate(environment));
 
   environment["compiler"] = "dart2js";
   environment["runtime"] = "ie9";
   Expect.isFalse(expression.evaluate(environment));
   environment["runtime"] = "chrome";
   Expect.isTrue(expression.evaluate(environment));
 }