fix: add exported const of NoopSpan instance (open-telemetry#139)

* fix: add exported const of NoopSpan instance

* fix: add INVALID_SPAN_CONTEXT as default value

* fix: remove instance suffix

Author: mayurkale22

packages/opentelemetry-basic-tracer/src/BasicTracer.ts

@@ -22,7 +22,7 @@ import {
   NoopSpan,
   randomSpanId,
   randomTraceId,
-  INVALID_SPAN_CONTEXT,
+  NOOP_SPAN,
   ALWAYS_SAMPLER,
 } from '@opentelemetry/core';
 import { BasicTracerConfig } from '../src/types';
@@ -32,13 +32,11 @@ import { BinaryFormat, HttpTextFormat } from '@opentelemetry/types';
  * This class represents a basic tracer.
  */
 export class BasicTracer implements types.Tracer {
-  static defaultSpan = new NoopSpan(INVALID_SPAN_CONTEXT);
-
-  private _defaultAttributes: types.Attributes;
-  private _binaryFormat: types.BinaryFormat;
-  private _httpTextFormat: types.HttpTextFormat;
-  private _sampler: types.Sampler;
-  private _scopeManager: ScopeManager;
+  private readonly _defaultAttributes: types.Attributes;
+  private readonly _binaryFormat: types.BinaryFormat;
+  private readonly _httpTextFormat: types.HttpTextFormat;
+  private readonly _sampler: types.Sampler;
+  private readonly _scopeManager: ScopeManager;
 
   /**
    * Constructs a new Tracer instance.
@@ -74,7 +72,7 @@ export class BasicTracer implements types.Tracer {
     if (!this._sampler.shouldSample(parentSpanContext)) {
       // TODO: propagate SpanContext, for more information see
       // https://github.com/open-telemetry/opentelemetry-js/pull/99#issuecomment-513325536
-      return BasicTracer.defaultSpan;
+      return NOOP_SPAN;
     }
 
     // span context

packages/opentelemetry-basic-tracer/test/BasicTracer.test.ts

@@ -22,6 +22,7 @@ import {
   ALWAYS_SAMPLER,
   NEVER_SAMPLER,
   NoopLogger,
+  NOOP_SPAN,
 } from '@opentelemetry/core';
 import { NoopScopeManager } from '@opentelemetry/scope-base';
 
@@ -101,7 +102,7 @@ describe('BasicTracer', () => {
         scopeManager: new NoopScopeManager(),
       });
       const span = tracer.startSpan('my-span');
-      assert.deepStrictEqual(span, BasicTracer.defaultSpan);
+      assert.deepStrictEqual(span, NOOP_SPAN);
     });
 
     // @todo: implement

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

@@ -16,14 +16,17 @@
 
 import * as types from '@opentelemetry/types';
 import { SpanContext } from '@opentelemetry/types';
+import { INVALID_SPAN_CONTEXT } from '../trace/spancontext-utils';
 
 /**
  * The NoopSpan is the default {@link Span} that is used when no Span
- * implementation is available. All operations are no-op except context
+ * implementation is available. All operations are no-op including context
  * propagation.
  */
 export class NoopSpan implements types.Span {
-  constructor(private readonly _spanContext: SpanContext) {}
+  constructor(
+    private readonly _spanContext: SpanContext = INVALID_SPAN_CONTEXT
+  ) {}
 
   // Returns a SpanContext.
   context(): types.SpanContext {
@@ -68,3 +71,5 @@ export class NoopSpan implements types.Span {
     return false;
   }
 }
+
+export const NOOP_SPAN = new NoopSpan();

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

@@ -23,10 +23,7 @@ import {
 } from '@opentelemetry/types';
 import { NOOP_HTTP_TEXT_FORMAT } from '../context/propagation/NoopHttpTextFormat';
 import { NOOP_BINARY_FORMAT } from '../context/propagation/NoopBinaryFormat';
-import { NoopSpan } from './NoopSpan';
-import { INVALID_SPAN_CONTEXT } from './spancontext-utils';
-
-export const NOOP_SPAN = new NoopSpan(INVALID_SPAN_CONTEXT);
+import { NOOP_SPAN } from './NoopSpan';
 
 /**
  * No-op implementations of {@link Tracer}.

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

@@ -15,7 +15,8 @@
  */
 
 import * as assert from 'assert';
-import { NoopTracer, NOOP_SPAN } from '../../src/trace/NoopTracer';
+import { NoopTracer } from '../../src/trace/NoopTracer';
+import { NOOP_SPAN } from '../../src/trace/NoopSpan';
 import { SpanKind } from '@opentelemetry/types';
 
 describe('NoopTracer', () => {