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diff --git a/runtime/metrics/metrics_test.h b/runtime/metrics/metrics_test.h
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+++ b/runtime/metrics/metrics_test.h
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+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * 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 ART_RUNTIME_METRICS_METRICS_TEST_H_
+#define ART_RUNTIME_METRICS_METRICS_TEST_H_
+
+#include "metrics.h"
+
+#pragma clang diagnostic push
+#pragma clang diagnostic error "-Wconversion"
+
+namespace art {
+namespace metrics {
+namespace test {
+
+// This namespace contains functions that are helpful for testing metrics but should not be used in
+// production code.
+
+// A trivial MetricsBackend that does nothing for all of the members. This can be overridden by
+// test cases to test specific behaviors.
+class TestBackendBase : public MetricsBackend {
+ public:
+  void BeginSession([[maybe_unused]] const SessionData& session_data) override {}
+  void EndSession() override {}
+
+  void ReportCounter([[maybe_unused]] DatumId counter_type,
+                     [[maybe_unused]] uint64_t value) override {}
+
+  void ReportHistogram([[maybe_unused]] DatumId histogram_type,
+                       [[maybe_unused]] int64_t low_value_,
+                       [[maybe_unused]] int64_t high_value,
+                       [[maybe_unused]] const std::vector<uint32_t>& buckets) override {}
+};
+
+template <DatumId counter_type>
+uint64_t CounterValue(const MetricsCounter<counter_type>& counter) {
+  uint64_t counter_value{0};
+  struct CounterBackend : public TestBackendBase {
+    explicit CounterBackend(uint64_t* counter_value) : counter_value_{counter_value} {}
+
+    void ReportCounter(DatumId, uint64_t value) override { *counter_value_ = value; }
+
+    uint64_t* counter_value_;
+  } backend{&counter_value};
+  counter.Report(&backend);
+  return counter_value;
+}
+
+template <DatumId histogram_type, size_t num_buckets, int64_t low_value, int64_t high_value>
+std::vector<uint32_t> GetBuckets(
+    const MetricsHistogram<histogram_type, num_buckets, low_value, high_value>& histogram) {
+  std::vector<uint32_t> buckets;
+  struct HistogramBackend : public TestBackendBase {
+    explicit HistogramBackend(std::vector<uint32_t>* buckets) : buckets_{buckets} {}
+
+    void ReportHistogram(DatumId, int64_t, int64_t, const std::vector<uint32_t>& buckets) override {
+      *buckets_ = buckets;
+    }
+
+    std::vector<uint32_t>* buckets_;
+  } backend{&buckets};
+  histogram.Report(&backend);
+  return buckets;
+}
+
+}  // namespace test
+}  // namespace metrics
+}  // namespace art
+
+#pragma clang diagnostic pop  // -Wconversion
+
+#endif  // ART_RUNTIME_METRICS_METRICS_TEST_H_