create toTracestate method

Author: lobsterkatie

packages/tracing/src/span.ts

@@ -248,6 +248,20 @@ export class Span implements SpanInterface {
     return `${this.traceId}-${this.spanId}${sampledString}`;
   }
 
+  /**
+   * @inheritDoc
+   */
+  public toTracestate(): string | undefined {
+    const sentryTracestate = this.transaction?.metadata?.tracestate?.sentry || this._getNewTracestate();
+    let thirdpartyTracestate = this.transaction?.metadata?.tracestate?.thirdparty;
+
+    // if there's third-party data, add a leading comma; otherwise, convert from `undefined` to the empty string, so the
+    // end result doesn’t come out as `sentry=xxxxxundefined`
+    thirdpartyTracestate = thirdpartyTracestate ? `,${thirdpartyTracestate}` : '';
+
+    return `${sentryTracestate}${thirdpartyTracestate}`;
+  }
+
   /**
    * @inheritDoc
    */
@@ -290,13 +304,7 @@ export class Span implements SpanInterface {
    * @inheritDoc
    */
   public getTraceHeaders(): TraceHeaders {
-    // tracestates live on the transaction, so if this is a free-floating span, there won't be one
-    let tracestate;
-    if (this.transaction) {
-      tracestate = this.transaction.metadata?.tracestate?.sentry;
-    } else {
-      tracestate = this._getNewTracestate();
-    }
+    const tracestate = this.toTracestate();
 
     return {
       'sentry-trace': this.toTraceparent(),

packages/tracing/test/span.test.ts

@@ -1,8 +1,9 @@
 import { BrowserClient } from '@sentry/browser';
 import { Hub, Scope } from '@sentry/hub';
+import * as hubPackage from '@sentry/hub';
 
 import { Span, SpanStatus, Transaction } from '../src';
-import { SENTRY_TRACE_REGEX } from '../src/utils';
+import { computeTracestateValue, SENTRY_TRACE_REGEX } from '../src/utils';
 
 describe('Span', () => {
   let hub: Hub;
@@ -101,6 +102,48 @@ describe('Span', () => {
     });
   });
 
+  describe('toTracestate', () => {
+    const publicKey = 'dogsarebadatkeepingsecrets';
+    const release = 'off.leash.trail';
+    const environment = 'dogpark';
+    const traceId = '12312012123120121231201212312012';
+
+    const computedTracestate = `sentry=${computeTracestateValue({ traceId, environment, release, publicKey })}`;
+    const thirdpartyData = 'maisey=silly,charlie=goofy';
+
+    const hub = new Hub(
+      new BrowserClient({
+        dsn: 'https://[email protected]/12312012',
+        tracesSampleRate: 1,
+        release,
+        environment,
+      }),
+    );
+
+    test('no third-party data', () => {
+      const transaction = new Transaction({ name: 'FETCH /ball', traceId }, hub);
+      const span = transaction.startChild({ op: 'dig.hole' });
+
+      expect(span.toTracestate()).toEqual(computedTracestate);
+    });
+
+    test('third-party data', () => {
+      const transaction = new Transaction({ name: 'FETCH /ball' }, hub);
+      transaction.setMetadata({ tracestate: { sentry: computedTracestate, thirdparty: thirdpartyData } });
+      const span = transaction.startChild({ op: 'dig.hole' });
+
+      expect(span.toTracestate()).toEqual(`${computedTracestate},${thirdpartyData}`);
+    });
+
+    test('orphan span', () => {
+      jest.spyOn(hubPackage, 'getCurrentHub').mockReturnValueOnce(hub);
+      const span = new Span({ op: 'dig.hole' });
+      span.traceId = traceId;
+
+      expect(span.toTracestate()).toEqual(computedTracestate);
+    });
+  });
+
   describe('getTraceHeaders', () => {
     it('returns correct headers', () => {
       const hub = new Hub(

packages/types/src/span.ts

@@ -149,9 +149,12 @@ export interface Span extends SpanContext {
    */
   isSuccess(): boolean;
 
-  /** Return a traceparent compatible header string */
+  /** Return a traceparent-compatible header string */
   toTraceparent(): string;
 
+  /** Return a tracestate-compatible header string. Returns undefined if there is no client or no DSN. */
+  toTracestate(): string | undefined;
+
   /** Returns the current span properties as a `SpanContext` */
   toContext(): SpanContext;