Add missed contextKey option to initTracer

src/configuration.js

@@ -225,6 +225,7 @@ export default class Configuration {
     }
 
     return new Tracer(config.serviceName, reporter, sampler, {
+      contextKey: options.contextKey,
       metrics: options.metrics,
       logger: options.logger,
       tags: options.tags,

src/tracer.js

@@ -54,6 +54,7 @@ export default class Tracer {
    * @param {Object} [options.metrics] - instance of the Metrics class from ./metrics/metrics.js.
    * @param {Object} [options.logger] - a logger matching NullLogger API from ./logger.js.
    * @param {Object} [options.baggageRestrictionManager] - a baggageRestrictionManager matching
+   * @param {Object} [options.contextKey] - a name of the key to extract/inject context from headers
    * BaggageRestrictionManager API from ./baggage.js.
    */
   constructor(

test/init_tracer.js

@@ -209,11 +209,13 @@ describe('initTracer', () => {
         tags: {
           x: 'y',
         },
+        contextKey: 'custom-header',
       }
     );
     assert.equal(tracer._logger, logger);
     assert.equal(tracer._metrics._factory, metrics);
     assert.equal(tracer._tags['x'], 'y');
+    assert.equal(tracer._injectors[opentracing.FORMAT_TEXT_MAP]._contextKey, 'custom-header');
     tracer.close(done);
   });