Add test logger implementation

test/test_logger.h

@@ -0,0 +1,97 @@
+/* vim:set ts=2 sw=2 sts=2 et: */
+/**
+ * \author     Marcus Holland-Moritz (github@mhxnet.de)
+ * \copyright  Copyright (c) Marcus Holland-Moritz
+ *
+ * This file is part of dwarfs.
+ *
+ * dwarfs is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * dwarfs is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with dwarfs.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <cstdlib>
+#include <mutex>
+#include <string>
+#include <vector>
+
+#include <folly/Conv.h>
+
+#include "dwarfs/logger.h"
+
+namespace dwarfs::test {
+
+class test_logger : public ::dwarfs::logger {
+ public:
+  struct log_entry {
+    log_entry(level_type level, std::string const& output, char const* file,
+              int line)
+        : level{level}
+        , output{output}
+        , file{file}
+        , line{line} {}
+
+    level_type level;
+    std::string output;
+    char const* file;
+    int line;
+  };
+
+  test_logger(level_type threshold = TRACE)
+      : threshold_{threshold}
+      , output_{debug_output_enabled()} {
+    if (output_ || threshold > level_type::INFO) {
+      set_policy<debug_logger_policy>();
+    } else {
+      set_policy<prod_logger_policy>();
+    }
+  }
+
+  void write(level_type level, std::string const& output, char const* file,
+             int line) override {
+    if (output_) {
+      std::lock_guard lock(mx_);
+      std::cerr << level_char(level) << " [" << file << ":" << line << "] "
+                << output << "\n";
+    }
+
+    if (level <= threshold_) {
+      std::lock_guard lock(mx_);
+      log_.emplace_back(level, output, file, line);
+    }
+  }
+
+  std::vector<log_entry> const& get_log() const { return log_; }
+
+  bool empty() const { return log_.empty(); }
+
+  void clear() { log_.clear(); }
+
+ private:
+  static bool debug_output_enabled() {
+    if (auto var = std::getenv("DWARFS_TEST_LOGGER_OUTPUT")) {
+      if (auto val = folly::tryTo<bool>(var); val && *val) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  std::mutex mx_;
+  std::vector<log_entry> log_;
+  level_type const threshold_;
+  bool const output_;
+};
+
+} // namespace dwarfs::test