fix: Added logger for react native which uses console.warn for error (optimizely#360)

Summary:

React Native App shows a full screen Red Message when console.error is called. This appears to be distracting for the developers. Added a new logger for React Native which uses console.warn to log error.

Test plan:

1. Manually tested thoroughly.
2. Added unit tests

Author: zashraf1985

packages/optimizely-sdk/lib/index.react_native.js

@@ -0,0 +1,121 @@
+/**
+ * Copyright 2019, Optimizely
+ *
+ * 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.
+ */
+var logging = require('@optimizely/js-sdk-logging');
+var fns = require('./utils/fns');
+var configValidator = require('./utils/config_validator');
+var defaultErrorHandler = require('./plugins/error_handler');
+var defaultEventDispatcher = require('./plugins/event_dispatcher/index.browser');
+var enums = require('./utils/enums');
+var loggerPlugin = require('./plugins/logger/index.react_native');
+var Optimizely = require('./optimizely');
+var eventProcessorConfigValidator = require('./utils/event_processor_config_validator');
+
+var logger = logging.getLogger();
+logging.setLogHandler(loggerPlugin.createLogger());
+logging.setLogLevel(logging.LogLevel.INFO);
+
+var DEFAULT_EVENT_BATCH_SIZE = 10;
+var DEFAULT_EVENT_FLUSH_INTERVAL = 1000; // Unit is ms, default is 1s
+
+/**
+ * Entry point into the Optimizely Javascript SDK for React Native
+ */
+module.exports = {
+  logging: loggerPlugin,
+  errorHandler: defaultErrorHandler,
+  eventDispatcher: defaultEventDispatcher,
+  enums: enums,
+
+  setLogger: logging.setLogHandler,
+  setLogLevel: logging.setLogLevel,
+
+  /**
+   * Creates an instance of the Optimizely class
+   * @param  {Object} config
+   * @param  {Object} config.datafile
+   * @param  {Object} config.errorHandler
+   * @param  {Object} config.eventDispatcher
+   * @param  {Object} config.logger
+   * @param  {Object} config.logLevel
+   * @param  {Object} config.userProfileService
+   * @param {Object} config.eventBatchSize
+   * @param {Object} config.eventFlushInterval
+   * @return {Object} the Optimizely object
+   */
+  createInstance: function(config) {
+    try {
+      config = config || {};
+
+      // TODO warn about setting per instance errorHandler / logger / logLevel
+      if (config.errorHandler) {
+        logging.setErrorHandler(config.errorHandler);
+      }
+      if (config.logger) {
+        logging.setLogHandler(config.logger);
+        // respect the logger's shouldLog functionality
+        logging.setLogLevel(logging.LogLevel.NOTSET);
+      }
+      if (config.logLevel !== undefined) {
+        logging.setLogLevel(config.logLevel);
+      }
+
+      try {
+        configValidator.validate(config);
+        config.isValidInstance = true;
+      } catch (ex) {
+        logger.error(ex);
+        config.isValidInstance = false;
+      }
+
+      // Explicitly check for null or undefined
+      // prettier-ignore
+      if (config.skipJSONValidation == null) { // eslint-disable-line eqeqeq
+        config.skipJSONValidation = true;
+      }
+
+      config = fns.assignIn(
+        {
+          clientEngine: enums.JAVASCRIPT_CLIENT_ENGINE,
+          eventBatchSize: DEFAULT_EVENT_BATCH_SIZE,
+          eventFlushInterval: DEFAULT_EVENT_FLUSH_INTERVAL,
+        },
+        config,
+        {
+          eventDispatcher: config.eventDispatcher,
+          // always get the OptimizelyLogger facade from logging
+          logger: logger,
+          errorHandler: logging.getErrorHandler(),
+        }
+      );
+
+      if (!eventProcessorConfigValidator.validateEventBatchSize(config.eventBatchSize)) {
+        logger.warn('Invalid eventBatchSize %s, defaulting to %s', config.eventBatchSize, DEFAULT_EVENT_BATCH_SIZE);
+        config.eventBatchSize = DEFAULT_EVENT_BATCH_SIZE;
+      }
+      if (!eventProcessorConfigValidator.validateEventFlushInterval(config.eventFlushInterval)) {
+        logger.warn('Invalid eventFlushInterval %s, defaulting to %s', config.eventFlushInterval, DEFAULT_EVENT_FLUSH_INTERVAL);
+        config.eventFlushInterval = DEFAULT_EVENT_FLUSH_INTERVAL;
+      }
+
+      var optimizely = new Optimizely(config);
+
+      return optimizely;
+    } catch (e) {
+      logger.error(e);
+      return null;
+    }
+  },
+};