Add a basic logging framework

Create a basic system to emit diagnostics to the user during operation.
Mimic the glog API for the most part, but use an output format similar
to that of coreutils and other established command-line tools.

Reviewed-by: Alex Chernyakhovsky <achernya@google.com>

1 files changed, 60 insertions, 0 deletions

diff --git a/log_test.cc b/log_test.cc
new file mode 100644
index 0000000..cec1199
--- /dev/null
+++ b/log_test.cc
@@ -0,0 +1,60 @@
+// Copyright 2021 Google LLC
+//
+// 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
+//
+//     https://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 "log.h"
+
+#include <iostream>
+#include <sstream>
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+namespace gsrsup {
+namespace {
+
+using ::testing::HasSubstr;
+using ::testing::IsEmpty;
+
+TEST(LogTest, FormatsProgramAndMessage) {
+  std::ostringstream s;
+  Log("program", s).Message(Log::kInfo, "message");
+  EXPECT_EQ(s.str(), "program: message\n");
+}
+
+TEST(LogTest, FormatsLevelDebug) {
+  std::ostringstream s;
+  Log("program", Log::kDebug, s).Message(Log::kDebug, "message");
+  EXPECT_THAT(s.str(), HasSubstr("debug:"));
+}
+
+TEST(LogTest, FormatsLevelWarning) {
+  std::ostringstream s;
+  Log("program", s).Message(Log::kWarning, "message");
+  EXPECT_THAT(s.str(), HasSubstr("warning:"));
+}
+
+TEST(LogTest, FormatsLevelError) {
+  std::ostringstream s;
+  Log("program", s).Message(Log::kError, "message");
+  EXPECT_THAT(s.str(), HasSubstr("error:"));
+}
+
+TEST(LogTest, HidesUninterestingMessages) {
+  std::ostringstream s;
+  Log("program", Log::kError, s).Message(Log::kDebug, "some debug message");
+  EXPECT_THAT(s.str(), IsEmpty());
+}
+
+}  // namespace
+}  // namespace gsrsup