refactor(logger): provide getLogger helper and remove NoopLogger class implementation [#1754]

.gitignore

@@ -79,6 +79,9 @@ package.json.lerna_backup
 # VsCode configs
 .vscode/
 
+# Vs configs
+.vs/
+
 #IDEA
 .idea
 *.iml

packages/opentelemetry-api/src/index.ts

@@ -26,7 +26,7 @@ export * from './trace/attributes';
 export * from './trace/Event';
 export * from './trace/link_context';
 export * from './trace/link';
-export * from './trace/NoopLogger';
+export * from './trace/getLogger';
 export * from './trace/NoopSpan';
 export * from './trace/NoopTracer';
 export * from './trace/NoopTracerProvider';

packages/opentelemetry-api/src/trace/getLogger.ts

@@ -0,0 +1,58 @@
+/*
+ * Copyright The OpenTelemetry 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
+ *
+ *      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.
+ */
+
+import { Logger } from '../common/Logger';
+
+function noopLoggerFunc(_message: string, ..._args: unknown[]): void {}
+
+/**
+ * Simple helper to check if the provided logger is defined and contains all of the expected functions
+ * @param logger
+ */
+function isLogger(logger?: Logger | null): logger is Logger {
+  return (
+    !!logger &&
+    !!logger.error &&
+    !!logger.warn &&
+    !!logger.info &&
+    !!logger.debug
+  );
+}
+
+/**
+ * Helper function to return a logger, the returned logger will be either the passed logger (if defined and valid)
+ * a ConsoleLogger (if useConsole is true) or a Noop Logger implementation.
+ * If the supplied logger is not valid (defined and contains the expected logger methods) and the useConsole parameter is
+ * true then you can also supply the required logging level, the the level is not defined then the environment logging level
+ * will be used.
+ * You can use this helper to avoid adding common boilerplate code to ensure you have a non-null or undefined logger.
+ * @param logger The available logger
+ * @param useConsole - If the logger is not valid should a ConsoleLogger be returned
+ * @param consoleLevel If no logger if
+ */
+export function getLogger(logger?: Logger | null): Logger {
+  if (!isLogger(logger)) {
+    // Create a dummy logger that does nothing.
+    logger = {
+      error: noopLoggerFunc,
+      warn: noopLoggerFunc,
+      info: noopLoggerFunc,
+      debug: noopLoggerFunc,
+    };
+  }
+
+  return logger;
+}