Implement function entry breakpoints in Observatory debugger.

runtime/observatory/test/debugging_test.dart

Index: runtime/observatory/test/debugging_test.dart
diff --git a/runtime/observatory/test/debugging_test.dart b/runtime/observatory/test/debugging_test.dart
index 070d9952bfd9040cc29c0a23271505e76142c807..51204e7dbab7c4f10b69a88dfb75beb443ce6d2d 100644
--- a/runtime/observatory/test/debugging_test.dart
+++ b/runtime/observatory/test/debugging_test.dart
@@ -7,11 +7,15 @@ import 'package:unittest/unittest.dart';
 import 'test_helper.dart';
 import 'dart:async';
 
+void helper(i) {
+  print(i);
+}
+
 void testFunction() {
   int i = 0;
   while (true) {
     if (++i % 100000000 == 0) {
-      print(i);   // line 14
+      helper(i);  // line 18
     }
   }
 }
@@ -43,13 +47,15 @@ var tests = [
       // Set up a listener to wait for breakpoint events.
       Completer completer = new Completer();
       List events = [];
-      isolate.vm.events.stream.listen((ServiceEvent event) {
+      var subscription;
+      subscription = isolate.vm.events.stream.listen((ServiceEvent event) {
         if (event.eventType.startsWith('Breakpoint')) {
           events.add(event);
           if (events.length == 2) {
             expect(events[0].eventType, equals('BreakpointResolved'));
             expect(events[1].eventType, equals('BreakpointReached'));
             print('Breakpoint reached');
+            subscription.cancel();
             completer.complete();
           }
         }
@@ -57,12 +63,12 @@ var tests = [
 
       // Add the breakpoint.
       var script = isolate.rootLib.scripts[0];
-      return isolate.addBreakpoint(script, 14).then((result) {
+      return isolate.addBreakpoint(script, 18).then((result) {
           expect(result is Breakpoint, isTrue);
           Breakpoint bpt = result;
           expect(bpt.type, equals('Breakpoint'));
           expect(bpt.script.id, equals(script.id));
-          expect(bpt.tokenPos, equals(51));
+          expect(bpt.tokenPos, equals(67));
           expect(isolate.breakpoints.length, equals(1));
           return completer.future;  // Wait for breakpoint events.
       });
@@ -83,10 +89,11 @@ var tests = [
   // Set up a listener to wait for breakpoint events.
   Completer completer = new Completer();
   List events = [];
-  isolate.vm.events.stream.listen((ServiceEvent event) {
-    if (event.eventType.startsWith('Breakpoint')) {
-      expect(event.eventType, equals('BreakpointReached'));
+  var subscription;
+  subscription = isolate.vm.events.stream.listen((ServiceEvent event) {
+    if (event.eventType.startsWith('BreakpointReached')) {
       print('Breakpoint reached');
+      subscription.cancel();
       completer.complete();
     }
   });
@@ -96,12 +103,12 @@ var tests = [
   });
 },
 
-// Get the stack trace again.  We are in 'print'.
+// Get the stack trace again.  We are in 'helper'.
 (Isolate isolate) {
   return isolate.getStack().then((ServiceMap stack) {
       expect(stack.type, equals('Stack'));
       expect(stack['frames'].length, greaterThanOrEqualTo(2));
-      expect(stack['frames'][0]['function'].name, equals('print'));
+      expect(stack['frames'][0]['function'].name, equals('helper'));
   });
 },
 
@@ -114,6 +121,44 @@ var tests = [
   });
 },
 
+// Resume
+(Isolate isolate) {
+  return isolate.resume().then((_) {
+      expect(isolate.pauseEvent == null, isTrue);
+  });
+},
+
+// Add breakpoint at function entry
+(Isolate isolate) {
+  // Set up a listener to wait for breakpoint events.
+  Completer completer = new Completer();
+  List events = [];
+  var subscription;
+  subscription = isolate.vm.events.stream.listen((ServiceEvent event) {
+    if (event.eventType.startsWith('BreakpointReached')) {
+      print('Breakpoint reached');
+      subscription.cancel();
+      completer.complete();
+    }
+  });
+  
+  // Find a specific function.
+  ServiceFunction function = isolate.rootLib.functions.firstWhere(
+      (f) => f.name == 'helper');
+  expect(function, isNotNull);
+
+  // Add the breakpoint at function entry
+  return isolate.addBreakpointAtEntry(function).then((result) {
+    expect(result is Breakpoint, isTrue);
+    Breakpoint bpt = result;
+    expect(bpt.type, equals('Breakpoint'));
+    expect(bpt.script.name, equals('debugging_test.dart'));
+    expect(bpt.tokenPos, equals(29));
+    expect(isolate.breakpoints.length, equals(1));
+    return completer.future;  // Wait for breakpoint events.
+  });
+},
+
 ];
 
 main(args) => runIsolateTests(args, tests, testeeConcurrent: testFunction);