diff --git a/cartographer/pose_graph/internal/testing/test_helpers.h b/cartographer/pose_graph/internal/testing/test_helpers.h
new file mode 100644
index 0000000..13664d8
--- /dev/null
+++ b/cartographer/pose_graph/internal/testing/test_helpers.h
@@ -0,0 +1,40 @@
+/*
+ * Copyright 2018 The Cartographer Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef CARTOGRAPHER_POSE_GRAPH_INTERNAL_TESTING_TEST_HELPERS_H_
+#define CARTOGRAPHER_POSE_GRAPH_INTERNAL_TESTING_TEST_HELPERS_H_
+
+#include "gmock/gmock.h"
+#include "google/protobuf/text_format.h"
+#include "google/protobuf/util/message_differencer.h"
+
+namespace cartographer {
+namespace testing {
+
+MATCHER_P(EqualsProto, expected_proto_string, "") {
+  using ConstProtoType = typename std::remove_reference<decltype(arg)>::type;
+
+  typename std::remove_cv<ConstProtoType>::type expected_proto;
+  EXPECT_TRUE(google::protobuf::TextFormat::ParseFromString(
+      expected_proto_string, &expected_proto));
+  return google::protobuf::util::MessageDifferencer::Equals(arg,
+                                                            expected_proto);
+}
+
+}  // namespace testing
+}  // namespace cartographer
+
+#endif  // CARTOGRAPHER_POSE_GRAPH_INTERNAL_TESTING_TEST_HELPERS_H_
diff --git a/cartographer/pose_graph/pose_2d_test.cc b/cartographer/pose_graph/pose_2d_test.cc
index 1e40166..a8c57cc 100644
--- a/cartographer/pose_graph/pose_2d_test.cc
+++ b/cartographer/pose_graph/pose_2d_test.cc
@@ -16,10 +16,7 @@
 
 #include "cartographer/pose_graph/pose_2d.h"
 
-#include "gmock/gmock.h"
-#include "google/protobuf/text_format.h"
-#include "google/protobuf/util/message_differencer.h"
-#include "gtest/gtest.h"
+#include "cartographer/pose_graph/internal/testing/test_helpers.h"
 
 namespace cartographer {
 namespace pose_graph {
@@ -36,20 +33,9 @@ constexpr char kExpectedNode[] = R"PROTO(
   }
 )PROTO";
 
-// TODO(pifon): Move this to a separate header.
-MATCHER_P(EqualsProto, expected_proto_string, "") {
-  using ConstProtoType = typename std::remove_reference<decltype(arg)>::type;
-
-  typename std::remove_cv<ConstProtoType>::type expected_proto;
-  EXPECT_TRUE(google::protobuf::TextFormat::ParseFromString(
-      expected_proto_string, &expected_proto));
-  return google::protobuf::util::MessageDifferencer::Equals(arg,
-                                                            expected_proto);
-}
-
-TEST(Pose2DTest, SerializeToProto) {
+TEST(Pose2DTest, ToProto) {
   Pose2D pose_2d("flat_world", true, Eigen::Vector2d(1., 2.), 5.);
-  EXPECT_THAT(pose_2d.ToProto(), EqualsProto(kExpectedNode));
+  EXPECT_THAT(pose_2d.ToProto(), testing::EqualsProto(kExpectedNode));
 }
 
 }  // namespace