Replace the configuration map with a typed object.

tests/standalone/status_expression_test.dart

Index: tests/standalone/status_expression_test.dart
diff --git a/tests/standalone/status_expression_test.dart b/tests/standalone/status_expression_test.dart
index 870670674ad5f7984f993eb63e555bb88962b311..98429ae5cbf922eb70082fd220b494a73c1e71d6 100644
--- a/tests/standalone/status_expression_test.dart
+++ b/tests/standalone/status_expression_test.dart
@@ -2,11 +2,22 @@
 // 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 "../../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();
@@ -22,7 +33,7 @@ void testExpression() {
       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";
@@ -49,11 +60,8 @@ void testBoolean() {
       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";
@@ -75,10 +83,10 @@ void testNotEqual() {
       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";