Adds test for noop factory

packages/opentelemetry-core/src/trace/TracerFactoryDelegate.ts

@@ -18,7 +18,7 @@ import * as types from '@opentelemetry/types';
 import { NoopTracerFactory } from './NoopTracerFactory';
 
 // Acts a bridge to the global tracer factory that can be safely called before the
-// global tracer is initialized. The purpose of the delegation is to avoid the
+// global tracer factory is initialized. The purpose of the delegation is to avoid the
 // sometimes nearly intractable initialization order problems that can arise in
 // applications with a complex set of dependencies. Also allows for the factory
 // to be changed/disabled during runtime without needing to change reference
@@ -48,13 +48,12 @@ export class TracerFactoryDelegate implements types.TracerFactory {
       this._tracerFactory || this._fallbackTracerFactory;
   }
 
-  // Stop the delegate from using the provided tracer. Begin to use the fallback tracer
+  // Stop the delegate from using the provided tracer factory. Begin to use the fallback factory
   stop(): void {
     this._currentTracerFactory = this._fallbackTracerFactory;
   }
 
   // -- TracerFactory interface implementation below -- //
-
   getTracer(name?: string, version?: string): types.Tracer {
     return this._currentTracerFactory.getTracer.apply(
       this._currentTracerFactory,

packages/opentelemetry-core/test/trace/NoopTraceFactory.test.ts

@@ -0,0 +1,12 @@
+import * as assert from 'assert';
+import { NoopTracer } from '../../src/trace/NoopTracer';
+import { NoopTracerFactory } from '../../src/trace/NoopTracerFactory';
+import { NOOP_SPAN } from '../../src/trace/NoopSpan';
+
+describe('NoopTracerFactory', () => {
+  it('should return a NOOP_SPAN', () => {
+    const factory = new NoopTracerFactory();
+    const span = factory.getTracer().startSpan('my-span')
+    assert.deepStrictEqual(span, NOOP_SPAN);
+  })
+})