Change --benchmark_list_tests to respect the benchmark filter.

This behavior mirrors how GTest handles these two flags.

include/benchmark/benchmark_api.h

@@ -160,11 +160,14 @@ class BenchmarkReporter;
 
 void Initialize(int* argc, char** argv);
 
-// Run all benchmarks which match the specified --benchmark_filter flag.
+// Generate a list of benchmarks matching the specified --benchmark_filter flag
+// and if --benchmark_list_tests is specified return after printing the name
+// of each matching benchmark. Otherwise run each matching benchmark and
+// report the results.
+//
 // The second overload reports the results using the specified 'reporter'.
 //
-// RETURNS: The number of benchmarks run, not including repetitions. If
-// '--benchmark_list_tests' is specified '0' is returned.
+// RETURNS: The number of matching benchmarks.
 size_t RunSpecifiedBenchmarks();
 size_t RunSpecifiedBenchmarks(BenchmarkReporter* reporter);
 

src/benchmark.cc

@@ -853,24 +853,9 @@ void State::SetLabel(const char* label) {
 namespace internal {
 namespace {
 
-void PrintBenchmarkList() {
-  std::vector<Benchmark::Instance> benchmarks;
-  auto families = BenchmarkFamilies::GetInstance();
-  if (!families->FindBenchmarks(".", &benchmarks)) return;
-
-  for (const internal::Benchmark::Instance& benchmark : benchmarks) {
-    std::cout <<  benchmark.name << "\n";
-  }
-}
-
-size_t RunMatchingBenchmarks(const std::string& spec,
+void RunMatchingBenchmarks(const std::vector<Benchmark::Instance>& benchmarks,
                            BenchmarkReporter* reporter) {
   CHECK(reporter != nullptr);
-  CHECK(!spec.empty());
-
-  std::vector<Benchmark::Instance> benchmarks;
-  auto families = BenchmarkFamilies::GetInstance();
-  if (!families->FindBenchmarks(spec, &benchmarks)) return 0;
 
   // Determine the width of the name field using a minimum width of 10.
   size_t name_field_width = 10;
@@ -894,7 +879,6 @@ size_t RunMatchingBenchmarks(const std::string& spec,
       RunBenchmark(benchmark, reporter);
     }
   }
-  return benchmarks.size();
 }
 
 std::unique_ptr<BenchmarkReporter> GetDefaultReporter() {
@@ -919,22 +903,27 @@ size_t RunSpecifiedBenchmarks() {
 }
 
 size_t RunSpecifiedBenchmarks(BenchmarkReporter* reporter) {
-  if (FLAGS_benchmark_list_tests) {
-    internal::PrintBenchmarkList();
-    return 0;
-  }
   std::string spec = FLAGS_benchmark_filter;
   if (spec.empty() || spec == "all")
     spec = ".";  // Regexp that matches all benchmarks
 
+  std::vector<internal::Benchmark::Instance> benchmarks;
+  auto families = internal::BenchmarkFamilies::GetInstance();
+  if (!families->FindBenchmarks(spec, &benchmarks)) return 0;
+
+  if (FLAGS_benchmark_list_tests) {
+    for (auto const& benchmark : benchmarks)
+      std::cout <<  benchmark.name << "\n";
+  } else {
     std::unique_ptr<BenchmarkReporter> default_reporter;
     if (!reporter) {
       default_reporter = internal::GetDefaultReporter();
       reporter = default_reporter.get();
     }
-  size_t num_run = internal::RunMatchingBenchmarks(spec, reporter);
+    internal::RunMatchingBenchmarks(benchmarks, reporter);
     reporter->Finalize();
-  return num_run;
+  }
+  return benchmarks.size();
 }
 
 namespace internal {

test/CMakeLists.txt

@@ -14,6 +14,7 @@ add_test(benchmark benchmark_test --benchmark_min_time=0.01)
 compile_benchmark_test(filter_test)
 macro(add_filter_test name filter expect)
   add_test(${name} filter_test --benchmark_min_time=0.01 --benchmark_filter=${filter} ${expect})
+  add_test(${name}_list_only filter_test --benchmark_list_tests --benchmark_filter=${filter} ${expect})
 endmacro(add_filter_test)
 
 add_filter_test(filter_simple "Foo" 3)

test/filter_test.cc

@@ -68,7 +68,11 @@ BENCHMARK(BM_FooBa);
 
 
 
-int main(int argc, char* argv[]) {
+int main(int argc, char** argv) {
+  bool list_only = false;
+  for (int i=0; i < argc; ++i)
+    list_only |= std::string(argv[i]).find("--benchmark_list_tests") != std::string::npos;
+
   benchmark::Initialize(&argc, argv);
 
   TestReporter test_reporter;
@@ -77,15 +81,25 @@ int main(int argc, char* argv[]) {
   if (argc == 2) {
     // Make sure we ran all of the tests
     std::stringstream ss(argv[1]);
-    size_t expected;
-    ss >> expected;
+    size_t expected_return;
+    ss >> expected_return;
 
-    const size_t count = test_reporter.GetCount();
-    if (count != expected || returned_count != expected) {
-      std::cerr << "ERROR: Expected " << expected << " tests to be run but returned_count = "
-                << returned_count << " and reporter_count = " << count << std::endl;
+    if (returned_count != expected_return) {
+      std::cerr << "ERROR: Expected " << expected_return
+                << " tests to match the filter but returned_count = "
+                << returned_count << std::endl;
+      return -1;
+    }
+
+    const size_t expected_reports = list_only ? 0 : expected_return;
+    const size_t reports_count = test_reporter.GetCount();
+    if (reports_count != expected_reports) {
+      std::cerr << "ERROR: Expected " << expected_reports
+                << " tests to be run but reported_count = " << reports_count
+                << std::endl;
       return -1;
     }
   }
+
   return 0;
 }