--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libcxx/utils/google-benchmark/test/display_aggregates_only_test.cc	Thu Feb 13 15:10:13 2020 +0900
@@ -0,0 +1,43 @@
+
+#undef NDEBUG
+#include <cstdio>
+#include <string>
+
+#include "benchmark/benchmark.h"
+#include "output_test.h"
+
+// Ok this test is super ugly. We want to check what happens with the file
+// reporter in the presence of DisplayAggregatesOnly().
+// We do not care about console output, the normal tests check that already.
+
+void BM_SummaryRepeat(benchmark::State& state) {
+  for (auto _ : state) {
+  }
+}
+BENCHMARK(BM_SummaryRepeat)->Repetitions(3)->DisplayAggregatesOnly();
+
+int main(int argc, char* argv[]) {
+  const std::string output = GetFileReporterOutput(argc, argv);
+
+  if (SubstrCnt(output, "\"name\": \"BM_SummaryRepeat/repeats:3") != 6 ||
+      SubstrCnt(output, "\"name\": \"BM_SummaryRepeat/repeats:3\"") != 3 ||
+      SubstrCnt(output, "\"name\": \"BM_SummaryRepeat/repeats:3_mean\"") != 1 ||
+      SubstrCnt(output, "\"name\": \"BM_SummaryRepeat/repeats:3_median\"") !=
+          1 ||
+      SubstrCnt(output, "\"name\": \"BM_SummaryRepeat/repeats:3_stddev\"") !=
+          1) {
+    std::cout << "Precondition mismatch. Expected to only find 6 "
+                 "occurrences of \"BM_SummaryRepeat/repeats:3\" substring:\n"
+                 "\"name\": \"BM_SummaryRepeat/repeats:3\", "
+                 "\"name\": \"BM_SummaryRepeat/repeats:3\", "
+                 "\"name\": \"BM_SummaryRepeat/repeats:3\", "
+                 "\"name\": \"BM_SummaryRepeat/repeats:3_mean\", "
+                 "\"name\": \"BM_SummaryRepeat/repeats:3_median\", "
+                 "\"name\": \"BM_SummaryRepeat/repeats:3_stddev\"\nThe entire "
+                 "output:\n";
+    std::cout << output;
+    return 1;
+  }
+
+  return 0;
+}