Add option to get the verbosity provided by commandline flag -v (#1330) (#1397)

* Add option to get the verbosity provided by commandline flag -v (#1330)

* replace assert with test failure

asserts are stripped out in non debug builds, and we run tests in non-debug CI bots.

* clang-format my own tweak

Co-authored-by: Dominic Hamon <dominichamon@users.noreply.github.com>

include/benchmark/benchmark.h

@@ -308,6 +308,9 @@ BENCHMARK_EXPORT std::string GetBenchmarkFilter();
 // `benchmark::Initialize()` will override the flag's value.
 BENCHMARK_EXPORT void SetBenchmarkFilter(std::string value);
 
+// Returns the current value of --v (command line value for verbosity).
+BENCHMARK_EXPORT int32_t GetBenchmarkVerbosity();
+
 // Creates a default display reporter. Used by the library when no display
 // reporter is provided, but also made available for external use in case a
 // custom reporter should respect the `--benchmark_format` flag as a fallback

src/benchmark.cc

@@ -539,6 +539,8 @@ void SetBenchmarkFilter(std::string value) {
   FLAGS_benchmark_filter = std::move(value);
 }
 
+int32_t GetBenchmarkVerbosity() { return FLAGS_v; }
+
 void RegisterMemoryManager(MemoryManager* manager) {
   internal::memory_manager = manager;
 }

test/BUILD

@@ -23,6 +23,7 @@ PER_SRC_TEST_ARGS = ({
     "user_counters_tabular_test.cc": ["--benchmark_counters_tabular=true"],
     "repetitions_test.cc": [" --benchmark_repetitions=3"],
     "spec_arg_test.cc" : ["--benchmark_filter=BM_NotChosen"],
+    "spec_arg_verbosity_test.cc" : ["--v=42"],
 })
 
 load("@rules_cc//cc:defs.bzl", "cc_library", "cc_test")

test/CMakeLists.txt

@@ -62,6 +62,9 @@ add_test(NAME benchmark COMMAND benchmark_test --benchmark_min_time=0.01)
 compile_benchmark_test(spec_arg_test)
 add_test(NAME spec_arg COMMAND spec_arg_test --benchmark_filter=BM_NotChosen)
 
+compile_benchmark_test(spec_arg_verbosity_test)
+add_test(NAME spec_arg_verbosity COMMAND spec_arg_verbosity_test --v=42)
+
 compile_benchmark_test(benchmark_setup_teardown_test)
 add_test(NAME benchmark_setup_teardown COMMAND benchmark_setup_teardown_test)
 

test/spec_arg_verbosity_test.cc

@@ -0,0 +1,43 @@
+#include <string.h>
+
+#include <iostream>
+
+#include "benchmark/benchmark.h"
+
+// Tests that the user specified verbosity level can be get.
+static void BM_Verbosity(benchmark::State& state) {
+  for (auto _ : state) {
+  }
+}
+BENCHMARK(BM_Verbosity);
+
+int main(int argc, char** argv) {
+  const int32_t flagv = 42;
+
+  // Verify that argv specify --v=42.
+  bool found = false;
+  for (int i = 0; i < argc; ++i) {
+    if (strcmp("--v=42", argv[i]) == 0) {
+      found = true;
+      break;
+    }
+  }
+  if (!found) {
+    std::cerr << "This test requires '--v=42' to be passed as a command-line "
+              << "argument.\n";
+    return 1;
+  }
+
+  benchmark::Initialize(&argc, argv);
+
+  // Check that the current flag value is reported accurately via the
+  // GetBenchmarkVerbosity() function.
+  if (flagv != benchmark::GetBenchmarkVerbosity()) {
+    std::cerr
+        << "Seeing different value for flags. GetBenchmarkVerbosity() returns ["
+        << benchmark::GetBenchmarkVerbosity() << "] expected flag=[" << flagv
+        << "]\n";
+    return 1;
+  }
+  return 0;
+}