static fromEnvironment()

in device/core/src/module_client.ts [393:416]
17 lines of code
6 McCabe index (conditional complexity)

  static fromEnvironment(transportCtor: any, callback?: Callback<ModuleClient>): Promise<ModuleClient> | void {
    return callbackToPromise((_callback) => {
      // Codes_SRS_NODE_MODULE_CLIENT_13_033: [ The fromEnvironment method shall throw a ReferenceError if the callback argument is falsy or is not a function. ]
      if (!_callback || typeof (_callback) !== 'function') {
        throw new ReferenceError('callback cannot be \'' + _callback + '\'');
      }

      // Codes_SRS_NODE_MODULE_CLIENT_13_026: [ The fromEnvironment method shall invoke callback with a ReferenceError if the transportCtor argument is falsy. ]
      if (!transportCtor) {
        _callback(new ReferenceError('transportCtor cannot be \'' + transportCtor + '\''));
        return;
      }

      // Codes_SRS_NODE_MODULE_CLIENT_13_028: [ The fromEnvironment method shall delegate to ModuleClient.fromConnectionString if an environment variable called EdgeHubConnectionString or IotHubConnectionString exists. ]

      // if the environment has a value for EdgeHubConnectionString then we use that
      const connectionString = process.env.EdgeHubConnectionString || process.env.IotHubConnectionString;
      if (connectionString) {
        ModuleClient._fromEnvironmentNormal(connectionString, transportCtor, _callback);
      } else {
        ModuleClient._fromEnvironmentEdge(transportCtor, _callback);
      }
    }, callback);
  }