Add output_type_test

pkg/compiler/lib/src/tracer.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 tracer;
 
 import 'dart:async' show EventSink;
 
 import '../compiler.dart' as api;
 import 'js_backend/namer.dart' show Namer;
 import 'ssa/nodes.dart' as ssa show HGraph;
 import 'ssa/ssa_tracer.dart' show HTracer;
 import 'util/util.dart' show Indentation;
 import 'world.dart' show ClosedWorld;
 
 /**
  * If non-null, we only trace methods whose name match the regexp defined by the
  * given pattern.
  */
-const String TRACE_FILTER_PATTERN = const String.fromEnvironment("DUMP_IR");
+String get TRACE_FILTER_PATTERN =>
+    TRACE_FILTER_PATTERN_FROM_ENVIRONMENT ?? TRACE_FILTER_PATTERN_FOR_TEST;
 
-final RegExp TRACE_FILTER =
-    TRACE_FILTER_PATTERN == null ? null : new RegExp(TRACE_FILTER_PATTERN);
+const String TRACE_FILTER_PATTERN_FROM_ENVIRONMENT =
+    const String.fromEnvironment("DUMP_IR");
+String TRACE_FILTER_PATTERN_FOR_TEST;
 
 /**
  * Dumps the intermediate representation after each phase in a format
  * readable by IR Hydra.
  */
 class Tracer extends TracerUtil {
   final ClosedWorld closedWorld;
   final Namer namer;
   bool traceActive = false;
   final EventSink<String> output;
-  final bool isEnabled = TRACE_FILTER != null;
+  final RegExp traceFilter;
 
   Tracer(
       this.closedWorld, this.namer, api.CompilerOutputProvider outputProvider)
-      : output = TRACE_FILTER != null ? outputProvider('dart', 'cfg') : null;
+      : traceFilter = TRACE_FILTER_PATTERN == null
+            ? null
+            : new RegExp(TRACE_FILTER_PATTERN),
+        output =
+            TRACE_FILTER_PATTERN != null ? outputProvider('dart', 'cfg') : null;
+
+  bool get isEnabled => traceFilter != null;
 
   void traceCompilation(String methodName) {
     if (!isEnabled) return;
-    traceActive = TRACE_FILTER.hasMatch(methodName);
+    traceActive = traceFilter.hasMatch(methodName);
     if (!traceActive) return;
     tag("compilation", () {
       printProperty("name", methodName);
       printProperty("method", methodName);
       printProperty("date", new DateTime.now().millisecondsSinceEpoch);
     });
   }
 
   void traceGraph(String name, var irObject) {
     if (!traceActive) return;
@@ skipping 46 matching lines @@
   }
 
   void add(String string) {
     output.add(string);
   }
 
   void addIndent() {
     add(_ind.indentation);
   }
 }