feat: benchmark_list_tests benchmark-format=json

include/benchmark/benchmark.h

@@ -1878,6 +1878,20 @@ class BENCHMARK_EXPORT BenchmarkReporter {
   // REQUIRES: 'out' is non-null.
   static void PrintBasicContext(std::ostream* out, Context const& context);
 
+  /**
+   * @brief Lists and describes the provided benchmarks.
+   *
+   * This virtual method is intended to be overridden by derived classes
+   * to provide specific implementations for listing benchmarks.
+   * It can be used for outputting, logging, or any other operation
+   * needed to handle or display the benchmarks' names and metadata.
+   *
+   * @param benchmarks A vector containing names and details of benchmarks
+   *                   that need to be listed or processed.
+   */
+  virtual void List(
+      const std::vector<internal::BenchmarkInstance>& benchmarks) = 0;
+
  private:
   std::ostream* output_stream_;
   std::ostream* error_stream_;
@@ -1899,6 +1913,8 @@ class BENCHMARK_EXPORT ConsoleReporter : public BenchmarkReporter {
 
   bool ReportContext(const Context& context) BENCHMARK_OVERRIDE;
   void ReportRuns(const std::vector<Run>& reports) BENCHMARK_OVERRIDE;
+  void List(const std::vector<internal::BenchmarkInstance>& benchmarks)
+      BENCHMARK_OVERRIDE;
 
  protected:
   virtual void PrintRunData(const Run& report);
@@ -1916,6 +1932,8 @@ class BENCHMARK_EXPORT JSONReporter : public BenchmarkReporter {
   bool ReportContext(const Context& context) BENCHMARK_OVERRIDE;
   void ReportRuns(const std::vector<Run>& reports) BENCHMARK_OVERRIDE;
   void Finalize() BENCHMARK_OVERRIDE;
+  void List(const std::vector<internal::BenchmarkInstance>& benchmarks)
+      BENCHMARK_OVERRIDE;
 
  private:
   void PrintRunData(const Run& report);
@@ -1930,6 +1948,8 @@ class BENCHMARK_EXPORT BENCHMARK_DEPRECATED_MSG(
   CSVReporter() : printed_header_(false) {}
   bool ReportContext(const Context& context) BENCHMARK_OVERRIDE;
   void ReportRuns(const std::vector<Run>& reports) BENCHMARK_OVERRIDE;
+  void List(const std::vector<internal::BenchmarkInstance>& benchmarks)
+      BENCHMARK_OVERRIDE;
 
  private:
   void PrintRunData(const Run& report);

src/benchmark.cc

@@ -556,7 +556,6 @@ size_t RunSpecifiedBenchmarks(BenchmarkReporter* display_reporter,
     default_display_reporter.reset(CreateDefaultDisplayReporter());
     display_reporter = default_display_reporter.get();
   }
-  auto& Out = display_reporter->GetOutputStream();
   auto& Err = display_reporter->GetErrorStream();
 
   std::string const& fname = FLAGS_benchmark_out;
@@ -592,8 +591,13 @@ size_t RunSpecifiedBenchmarks(BenchmarkReporter* display_reporter,
   }
 
   if (FLAGS_benchmark_list_tests) {
-    for (auto const& benchmark : benchmarks)
-      Out << benchmark.name().str() << "\n";
+    if (FLAGS_benchmark_format == "json") {
+      JSONReporter json_reporter;
+      json_reporter.List(benchmarks);
+    } else {
+      benchmark::ConsoleReporter console_reporter;
+      console_reporter.List(benchmarks);
+    }
   } else {
     internal::RunBenchmarks(benchmarks, display_reporter, file_reporter);
   }

src/console_reporter.cc

@@ -21,7 +21,7 @@
 #include <tuple>
 #include <vector>
 
-#include "benchmark/benchmark.h"
+#include "benchmark_api_internal.h"
 #include "check.h"
 #include "colorprint.h"
 #include "commandlineflags.h"
@@ -203,4 +203,13 @@ void ConsoleReporter::PrintRunData(const Run& result) {
   printer(Out, COLOR_DEFAULT, "\n");
 }
 
+BENCHMARK_EXPORT
+void ConsoleReporter::List(
+    const std::vector<internal::BenchmarkInstance>& benchmarks) {
+  std::ostream& Out = GetOutputStream();
+  for (auto const& benchmark : benchmarks) {
+    Out << benchmark.name().str() << "\n";
+  }
+}
+
 }  // end namespace benchmark

src/csv_reporter.cc

@@ -19,7 +19,7 @@
 #include <tuple>
 #include <vector>
 
-#include "benchmark/benchmark.h"
+#include "benchmark_api_internal.h"
 #include "check.h"
 #include "complexity.h"
 #include "string_util.h"
@@ -158,4 +158,11 @@ void CSVReporter::PrintRunData(const Run& run) {
   Out << '\n';
 }
 
+void CSVReporter::List(
+    const std::vector<internal::BenchmarkInstance>& benchmarks) {
+  (void)benchmarks;  // Suppress unused parameter warning
+  std::ostream& err = GetErrorStream();
+  err << "List() method is not implemented for CSVReporter.\n";
+}
+
 }  // end namespace benchmark

src/json_reporter.cc

@@ -22,7 +22,7 @@
 #include <tuple>
 #include <vector>
 
-#include "benchmark/benchmark.h"
+#include "benchmark_api_internal.h"
 #include "complexity.h"
 #include "string_util.h"
 #include "timers.h"
@@ -317,4 +317,18 @@ void JSONReporter::PrintRunData(Run const& run) {
 const int64_t MemoryManager::TombstoneValue =
     std::numeric_limits<int64_t>::max();
 
+void JSONReporter::List(
+    const std::vector<internal::BenchmarkInstance>& benchmarks) {
+  std::ostream& Out = GetOutputStream();
+  Out << "[";
+  for (size_t i = 0; i < benchmarks.size(); ++i) {
+    const auto& benchmark = benchmarks[i];
+    Out << "{ \"name\": \"" << benchmark.name().str() << "\" }";
+    if (i != benchmarks.size() - 1) {
+      Out << ", ";
+    }
+  }
+  Out << "]";
+}
+
 }  // end namespace benchmark

test/benchmark_random_interleaving_gtest.cc

@@ -40,6 +40,8 @@ class NullReporter : public BenchmarkReporter {
  public:
   bool ReportContext(const Context& /*context*/) override { return true; }
   void ReportRuns(const std::vector<Run>& /* report */) override {}
+  void List(
+      const std::vector<benchmark::internal::BenchmarkInstance>&) override {}
 };
 
 class BenchmarkTest : public testing::Test {

test/output_test_helper.cc

@@ -164,6 +164,14 @@ class TestReporter : public benchmark::BenchmarkReporter {
     for (auto rep : reporters_) rep->Finalize();
   }
 
+  void List(const std::vector<benchmark::internal::BenchmarkInstance>&
+                benchmarks) override {
+    // simply logging the status
+    for (const auto& benchmark : benchmarks) {
+      std::cout << benchmark.name().str() << std::endl;
+    }
+  }
+
  private:
   std::vector<benchmark::BenchmarkReporter*> reporters_;
 };