vm/service/observatory: Add coverage for functions, some tests, and fix buggy filter

runtime/vm/coverage_test.cc

Index: runtime/vm/coverage_test.cc
diff --git a/runtime/vm/coverage_test.cc b/runtime/vm/coverage_test.cc
index 6219212f8c74ab80dd6d9c10107b1dc775438fd9..e37cf67f6f870cd6e163a7be7e08df2ffb52dd1c 100644
--- a/runtime/vm/coverage_test.cc
+++ b/runtime/vm/coverage_test.cc
@@ -8,7 +8,7 @@
 
 namespace dart {
 
-static void ExecuteScript(const char* script) {
+static RawObject* ExecuteScript(const char* script) {
   Dart_Handle h_lib = TestCase::LoadTestScript(script, NULL);
   EXPECT_VALID(h_lib);
   Library& lib = Library::Handle();
@@ -16,9 +16,24 @@ static void ExecuteScript(const char* script) {
   EXPECT(!lib.IsNull());
   Dart_Handle result = Dart_Invoke(h_lib, NewString("main"), 0, NULL);
   EXPECT_VALID(result);
+  return Api::UnwrapHandle(h_lib);
 }
 
 
+class FunctionCoverageFilter : public CoverageFilter {
+ public:
+  explicit FunctionCoverageFilter(const Function& func) : func_(func) {}
+  bool ShouldOutputCoverageFor(const Library& lib,
+                               const String& script_url,
+                               const Class& cls,
+                               const Function& func) const {
+    return func.raw() == func_.raw();
+  }
+ private:
+  const Function& func_;
+};
+
+
 TEST_CASE(Coverage_Empty) {
   const char* kScript =
       "main() {\n"
@@ -77,4 +92,40 @@ TEST_CASE(Coverage_MainWithClass) {
       "\"kind\":\"script\"},\"hits\":[10,1,11,1]}", js.ToCString());
 }
 
+
+TEST_CASE(Coverage_FilterFunction) {
+  const char* kScript =
+      "class Foo {\n"
+      "  var x;\n"
+      "  var y;\n"
+      "  Foo(this.x);\n"
+      "  Foo.other(this.x, this.y);\n"
+      "  Foo.yetAnother();\n"
+      "}\n"
+      "main() {\n"
+      "  var foo = new Foo(7);\n"
+      "}\n";
+
+  Isolate* isolate = Isolate::Current();
+  Library& lib = Library::Handle();
+  lib ^= ExecuteScript(kScript);
+  ASSERT(!lib.IsNull());
+  const Class& cls = Class::Handle(
+      lib.LookupClass(String::Handle(String::New("Foo"))));
+  ASSERT(!cls.IsNull());
+  const Function& func = Function::Handle(
+      cls.LookupFunction(String::Handle(String::New("Foo.yetAnother"))));
+  ASSERT(!func.IsNull());
+
+  JSONStream js;
+  FunctionCoverageFilter filter(func);
+  CodeCoverage::PrintJSON(isolate, &js, &filter);
+  // Only expect coverage data for Foo.yetAnother() on line 6.
+  EXPECT_SUBSTRING(
+      "{\"source\":\"test-lib\",\"script\":{"
+      "\"type\":\"@Script\",\"id\":\"scripts\\/test-lib\","
+      "\"name\":\"test-lib\",\"user_name\":\"test-lib\","
+      "\"kind\":\"script\"},\"hits\":[6,0]}", js.ToCString());
+}
+
 }  // namespace dart