Fix handling of null pointers in JS bindings.

mojo/apps/js/test/js_to_cpp_unittest.cc

Index: mojo/apps/js/test/js_to_cpp_unittest.cc
diff --git a/mojo/apps/js/test/js_to_cpp_unittest.cc b/mojo/apps/js/test/js_to_cpp_unittest.cc
index 527c81b0966da08ad6fdc4d78995b326cb54632f..64259df156faaf7c2b00c4229412aa2edda00162 100644
--- a/mojo/apps/js/test/js_to_cpp_unittest.cc
+++ b/mojo/apps/js/test/js_to_cpp_unittest.cc
@@ -65,54 +65,6 @@ bool IsRunningOnIsolatedBot() {
   return false;
 }
 
-// NOTE: Callers will need to have established an AllocationScope, or you're
-// gonna have a bad time.
-js_to_cpp::EchoArgs BuildSampleEchoArgs() {
-    js_to_cpp::EchoArgs::Builder builder;
-    builder.set_si64(kExpectedInt64Value);
-    builder.set_si32(kExpectedInt32Value);
-    builder.set_si16(kExpectedInt16Value);
-    builder.set_si8(kExpectedInt8Value);
-    builder.set_ui64(kExpectedUInt64Value);
-    builder.set_ui32(kExpectedUInt32Value);
-    builder.set_ui16(kExpectedUInt16Value);
-    builder.set_ui8(kExpectedUInt8Value);
-    builder.set_float_val(kExpectedFloatVal);
-    builder.set_float_inf(kExpectedFloatInf);
-    builder.set_float_nan(kExpectedFloatNan);
-    builder.set_double_val(kExpectedDoubleVal);
-    builder.set_double_inf(kExpectedDoubleInf);
-    builder.set_double_nan(kExpectedDoubleNan);
-    builder.set_name("coming");
-    mojo::Array<mojo::String>::Builder string_array(3);
-    string_array[0] = "one";
-    string_array[1] = "two";
-    string_array[2] = "three";
-    builder.set_string_array(string_array.Finish());
-    return builder.Finish();
-}
-
-void CheckSampleEchoArgs(const js_to_cpp::EchoArgs& arg) {
-    EXPECT_EQ(kExpectedInt64Value, arg.si64());
-    EXPECT_EQ(kExpectedInt32Value, arg.si32());
-    EXPECT_EQ(kExpectedInt16Value, arg.si16());
-    EXPECT_EQ(kExpectedInt8Value, arg.si8());
-    EXPECT_EQ(kExpectedUInt64Value, arg.ui64());
-    EXPECT_EQ(kExpectedUInt32Value, arg.ui32());
-    EXPECT_EQ(kExpectedUInt16Value, arg.ui16());
-    EXPECT_EQ(kExpectedUInt8Value, arg.ui8());
-    EXPECT_EQ(kExpectedFloatVal, arg.float_val());
-    EXPECT_EQ(kExpectedFloatInf, arg.float_inf());
-    EXPECT_NAN(arg.float_nan());
-    EXPECT_EQ(kExpectedDoubleVal, arg.double_val());
-    EXPECT_EQ(kExpectedDoubleInf, arg.double_inf());
-    EXPECT_NAN(arg.double_nan());
-    EXPECT_EQ(std::string("coming"), arg.name().To<std::string>());
-    EXPECT_EQ(std::string("one"), arg.string_array()[0].To<std::string>());
-    EXPECT_EQ(std::string("two"), arg.string_array()[1].To<std::string>());
-    EXPECT_EQ(std::string("three"), arg.string_array()[2].To<std::string>());
-}
-
 void CheckDataPipe(MojoHandle data_pipe_handle) {
   char buffer[100];
   uint32_t buffer_size = static_cast<uint32_t>(sizeof(buffer));
@@ -125,6 +77,68 @@ void CheckDataPipe(MojoHandle data_pipe_handle) {
   }
 }
 
+// NOTE: Callers will need to have established an AllocationScope, or you're
+// gonna have a bad time.
+js_to_cpp::EchoArgs BuildSampleEchoArgs() {
+  js_to_cpp::EchoArgs::Builder builder;
+  builder.set_si64(kExpectedInt64Value);
+  builder.set_si32(kExpectedInt32Value);
+  builder.set_si16(kExpectedInt16Value);
+  builder.set_si8(kExpectedInt8Value);
+  builder.set_ui64(kExpectedUInt64Value);
+  builder.set_ui32(kExpectedUInt32Value);
+  builder.set_ui16(kExpectedUInt16Value);
+  builder.set_ui8(kExpectedUInt8Value);
+  builder.set_float_val(kExpectedFloatVal);
+  builder.set_float_inf(kExpectedFloatInf);
+  builder.set_float_nan(kExpectedFloatNan);
+  builder.set_double_val(kExpectedDoubleVal);
+  builder.set_double_inf(kExpectedDoubleInf);
+  builder.set_double_nan(kExpectedDoubleNan);
+  builder.set_name("coming");
+  mojo::Array<mojo::String>::Builder string_array(3);
+  string_array[0] = "one";
+  string_array[1] = "two";
+  string_array[2] = "three";
+  builder.set_string_array(string_array.Finish());
+  return builder.Finish();
+}
+
+void CheckSampleEchoArgs(const js_to_cpp::EchoArgs& arg) {
+  EXPECT_EQ(kExpectedInt64Value, arg.si64());
+  EXPECT_EQ(kExpectedInt32Value, arg.si32());
+  EXPECT_EQ(kExpectedInt16Value, arg.si16());
+  EXPECT_EQ(kExpectedInt8Value, arg.si8());
+  EXPECT_EQ(kExpectedUInt64Value, arg.ui64());
+  EXPECT_EQ(kExpectedUInt32Value, arg.ui32());
+  EXPECT_EQ(kExpectedUInt16Value, arg.ui16());
+  EXPECT_EQ(kExpectedUInt8Value, arg.ui8());
+  EXPECT_EQ(kExpectedFloatVal, arg.float_val());
+  EXPECT_EQ(kExpectedFloatInf, arg.float_inf());
+  EXPECT_NAN(arg.float_nan());
+  EXPECT_EQ(kExpectedDoubleVal, arg.double_val());
+  EXPECT_EQ(kExpectedDoubleInf, arg.double_inf());
+  EXPECT_NAN(arg.double_nan());
+  EXPECT_EQ(std::string("coming"), arg.name().To<std::string>());
+  EXPECT_EQ(std::string("one"), arg.string_array()[0].To<std::string>());
+  EXPECT_EQ(std::string("two"), arg.string_array()[1].To<std::string>());
+  EXPECT_EQ(std::string("three"), arg.string_array()[2].To<std::string>());
+  CheckDataPipe(arg.data_handle().get().value());
+}
+
+js_to_cpp::EchoArgsList BuildSampleEchoArgsList() {
+  js_to_cpp::EchoArgsList::Builder builder;
+  builder.set_item(BuildSampleEchoArgs());
+  return builder.Finish();
+}
+
+void CheckSampleEchoArgsList(const js_to_cpp::EchoArgsList& list) {
+  if (list.is_null())
+    return;
+  CheckSampleEchoArgs(list.item());
+  CheckSampleEchoArgsList(list.next());
+}
+
 void CheckCorruptedString(const mojo::String& arg) {
   // The values don't matter so long as all accesses are within bounds.
   if (arg.is_null())
@@ -168,8 +182,7 @@ class CppSideConnection : public js_to_cpp::CppSide {
     NOTREACHED();
   }
 
-  virtual void EchoResponse(const js_to_cpp::EchoArgs& arg1,
-                            const js_to_cpp::EchoArgs& arg2) OVERRIDE {
+  virtual void EchoResponse(const js_to_cpp::EchoArgsList& list) OVERRIDE {
     NOTREACHED();
   }
 
@@ -222,19 +235,18 @@ class EchoCppSideConnection : public CppSideConnection {
   // js_to_cpp::CppSide:
   virtual void StartTest() OVERRIDE {
     AllocationScope scope;
-    js_side_->Echo(kExpectedMessageCount, BuildSampleEchoArgs());
+    js_side_->Echo(kExpectedMessageCount, BuildSampleEchoArgsList());
   }
 
-  virtual void EchoResponse(const js_to_cpp::EchoArgs& arg1,
-                            const js_to_cpp::EchoArgs& arg2) OVERRIDE {
+  virtual void EchoResponse(const js_to_cpp::EchoArgsList& list) OVERRIDE {
+    const js_to_cpp::EchoArgs& special_arg = list.item();
     message_count_ += 1;
-    CheckSampleEchoArgs(arg1);
-    EXPECT_EQ(-1, arg2.si64());
-    EXPECT_EQ(-1, arg2.si32());
-    EXPECT_EQ(-1, arg2.si16());
-    EXPECT_EQ(-1, arg2.si8());
-    EXPECT_EQ(std::string("going"), arg2.name().To<std::string>());
-    CheckDataPipe(arg2.data_handle().get().value());
+    EXPECT_EQ(-1, special_arg.si64());
+    EXPECT_EQ(-1, special_arg.si32());
+    EXPECT_EQ(-1, special_arg.si16());
+    EXPECT_EQ(-1, special_arg.si8());
+    EXPECT_EQ(std::string("going"), special_arg.name().To<std::string>());
+    CheckSampleEchoArgsList(list.next());
   }
 
   virtual void TestFinished() OVERRIDE {