Add test for stats stdout exporter. (#158)

Author: g-easy

opencensus/exporters/stats/stdout/BUILD

@@ -31,3 +31,16 @@ cc_library(
         "@com_google_absl//absl/time",
     ],
 )
+
+cc_test(
+    name = "stdout_exporter_test",
+    srcs = ["internal/stdout_exporter_test.cc"],
+    copts = TEST_COPTS,
+    deps = [
+        ":stdout_exporter",
+        "//opencensus/stats",
+        "//opencensus/stats:test_utils",
+        "@com_google_absl//absl/time",
+        "@com_google_googletest//:gtest_main",
+    ],
+)

opencensus/exporters/stats/stdout/internal/stdout_exporter.cc

@@ -45,11 +45,10 @@ std::string DataToString(const opencensus::stats::Distribution& data) {
   return output;
 }
 
-}  // namespace
-
-class StdoutExporter::Handler
-    : public opencensus::stats::StatsExporter::Handler {
+class Handler : public opencensus::stats::StatsExporter::Handler {
  public:
+  Handler(std::ostream* stream) : stream_(stream) {}
+
   void ExportViewData(
       const std::vector<std::pair<opencensus::stats::ViewDescriptor,
                                   opencensus::stats::ViewData>>& data) override;
@@ -61,15 +60,11 @@ class StdoutExporter::Handler
       const opencensus::stats::ViewDescriptor& descriptor,
       absl::Time start_time, absl::Time end_time,
       const opencensus::stats::ViewData::DataMap<DataValueT>& data);
-};
 
-// static
-void StdoutExporter::Register() {
-  opencensus::stats::StatsExporter::RegisterPushHandler(
-      absl::make_unique<StdoutExporter::Handler>());
-}
+  std::ostream* stream_;
+};
 
-void StdoutExporter::Handler::ExportViewData(
+void Handler::ExportViewData(
     const std::vector<std::pair<opencensus::stats::ViewDescriptor,
                                 opencensus::stats::ViewData>>& data) {
   for (const auto& datum : data) {
@@ -92,18 +87,17 @@ void StdoutExporter::Handler::ExportViewData(
 }
 
 template <typename DataValueT>
-void StdoutExporter::Handler::ExportViewDataImpl(
+void Handler::ExportViewDataImpl(
     const opencensus::stats::ViewDescriptor& descriptor, absl::Time start_time,
     absl::Time end_time,
     const opencensus::stats::ViewData::DataMap<DataValueT>& data) {
   if (data.size() == 0) {
-    std::cout << absl::StrCat("No data for view \"", descriptor.name(),
-                              "\" from ", absl::FormatTime(start_time),
-                              ".\n\n");
+    *stream_ << absl::StrCat("No data for view \"", descriptor.name(),
+                             "\" from ", absl::FormatTime(start_time), ".\n\n");
     return;
   }
-  // Build a string so we can write it to cout in one shot to minimize crosstalk
-  // if multiple threads write to cout simultaneously.
+  // Build a string so we can write it in one shot to minimize crosstalk if
+  // multiple threads write to stream_ simultaneously.
   std::string output = absl::StrCat("Data for view \"", descriptor.name(),
                                     "\" from ", absl::FormatTime(start_time),
                                     " to ", absl::FormatTime(end_time), ":\n");
@@ -116,7 +110,15 @@ void StdoutExporter::Handler::ExportViewDataImpl(
     absl::StrAppend(&output, DataToString(row.second));
   }
   absl::StrAppend(&output, "\n");
-  std::cout << output;
+  *stream_ << output;
+}
+
+}  // namespace
+
+// static
+void StdoutExporter::Register(std::ostream* stream) {
+  opencensus::stats::StatsExporter::RegisterPushHandler(
+      absl::make_unique<Handler>(stream));
 }
 
 }  // namespace stats

opencensus/exporters/stats/stdout/internal/stdout_exporter_test.cc

@@ -0,0 +1,67 @@
+// Copyright 2018, OpenCensus Authors
+//
+// 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.
+
+#include "opencensus/exporters/stats/stdout/stdout_exporter.h"
+
+#include <iostream>
+#include <sstream>
+
+#include "absl/time/clock.h"
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "opencensus/stats/stats.h"
+#include "opencensus/stats/stats_exporter.h"
+#include "opencensus/stats/testing/test_utils.h"
+
+namespace opencensus {
+namespace stats {
+
+class StatsExporterTest {
+ public:
+  static constexpr auto& ExportForTesting = StatsExporter::ExportForTesting;
+};
+
+}  // namespace stats
+}  // namespace opencensus
+
+namespace {
+
+using ::testing::HasSubstr;
+
+TEST(StdoutExporterTest, Export) {
+  std::stringstream s;
+  ::opencensus::exporters::stats::StdoutExporter::Register(&s);
+
+  auto key = ::opencensus::stats::TagKey::Register("test_key");
+  auto measure = ::opencensus::stats::MeasureDouble::Register(
+      "example.com/Test/Measure", "Test description.", "1");
+  auto descriptor = ::opencensus::stats::ViewDescriptor()
+                        .set_name("example.com/Test/View")
+                        .set_measure("example.com/Test/Measure")
+                        .set_aggregation(opencensus::stats::Aggregation::Sum())
+                        .add_column(key);
+  descriptor.RegisterForExport();
+  ::opencensus::stats::Record({{measure, 123456.}}, {{key, "value1"}});
+
+  ::opencensus::stats::testing::TestUtils::Flush();
+  ::opencensus::stats::StatsExporterTest::ExportForTesting();
+
+  const std::string str = s.str();
+  std::cout << str;
+  EXPECT_THAT(str, HasSubstr("test_key"));
+  EXPECT_THAT(str, HasSubstr("value1"));
+  EXPECT_THAT(str, HasSubstr("123456"));
+}
+
+}  // namespace

opencensus/exporters/stats/stdout/stdout_exporter.h

@@ -15,18 +15,17 @@
 #ifndef OPENCENSUS_EXPORTERS_STATS_STDOUT_STDOUT_EXPORTER_H_
 #define OPENCENSUS_EXPORTERS_STATS_STDOUT_STDOUT_EXPORTER_H_
 
+#include <iostream>
+
 namespace opencensus {
 namespace exporters {
 namespace stats {
 
-// A stats exporter that exports views registered with StatsExporter to stdout.
-// StdoutExporter is immutable.
+// A stats exporter that writes to stdout.
 class StdoutExporter {
  public:
-  static void Register();
-
- private:
-  class Handler;
+  StdoutExporter() = delete;
+  static void Register(std::ostream* stream = &std::cout);
 };
 
 }  // namespace stats

opencensus/exporters/trace/stdout/internal/stdout_exporter.cc

@@ -44,6 +44,7 @@ class Handler : public ::opencensus::trace::exporter::SpanExporter::Handler {
 
 }  // namespace
 
+// static
 void StdoutExporter::Register(std::ostream* stream) {
   ::opencensus::trace::exporter::SpanExporter::RegisterHandler(
       absl::make_unique<Handler>(stream));