feat: SessionDuration integration

Author: kamilogorek

packages/integrations/src/index.ts

@@ -6,6 +6,7 @@ export { Ember } from './ember';
 export { ExtraErrorData } from './extraerrordata';
 export { ReportingObserver } from './reportingobserver';
 export { RewriteFrames } from './rewriteframes';
+export { SessionDuration } from './sessionduration';
 export { Tracing } from './tracing';
 export { Transaction } from './transaction';
 export { Vue } from './vue';

packages/integrations/src/sessionduration.ts

@@ -0,0 +1,42 @@
+import { Event, EventProcessor, Hub, Integration } from '@sentry/types';
+
+/** This function adds duration since Sentry was initialized till the time event was sent */
+export class SessionDuration implements Integration {
+  /**
+   * @inheritDoc
+   */
+  public name: string = SessionDuration.id;
+  /**
+   * @inheritDoc
+   */
+  public static id: string = 'SessionDuration';
+
+  /** Exact time Client was initialized expressed in milliseconds since Unix Epoch. */
+  protected readonly _startTime: number = Date.now();
+
+  /**
+   * @inheritDoc
+   */
+  public setupOnce(addGlobalEventProcessor: (callback: EventProcessor) => void, getCurrentHub: () => Hub): void {
+    addGlobalEventProcessor(event => {
+      const self = getCurrentHub().getIntegration(SessionDuration);
+      if (self) {
+        return self.process(event);
+      }
+      return event;
+    });
+  }
+
+  /**
+   * @inheritDoc
+   */
+  public process(event: Event): Event {
+    return {
+      ...event,
+      extra: {
+        ...event.extra,
+        ['session:duration']: Date.now() - this._startTime,
+      },
+    };
+  }
+}

packages/integrations/test/sessionduration.test.ts

@@ -0,0 +1,20 @@
+import { SessionDuration } from '../src/sessionduration';
+
+describe('SessionDuration', () => {
+  it('should work as expected', done => {
+    const sessionDuration: SessionDuration = new SessionDuration();
+
+    // Juuust in case so we know that 1ms passes
+    setTimeout(() => {
+      const event = sessionDuration.process({
+        extra: {
+          some: 'value',
+        },
+      });
+      expect(event.extra!['session:duration']).toBeGreaterThan(0);
+      expect(typeof event.extra!['session:duration']).toBe('number');
+      expect(event.extra!.some).toEqual('value');
+      done();
+    }, 1);
+  });
+});