Log perf test results to Posthog

Author: pimterry

.github/workflows/ci.yml

@@ -26,6 +26,8 @@ jobs:
           # Node v22+ needs no strip-types (because we use ts-node for full TS instead)
           NODE_OPTIONS: >-
             ${{ (!startsWith(matrix.node-version, '20') && '--no-experimental-strip-types') || '' }}
+          # We log performance test results to Posthog to track trends:
+          POSTHOG_PERF_API_KEY: ${{ secrets.POSTHOG_PERF_API_KEY }}
 
       - name: Deploy docs
         if: github.ref == 'refs/heads/main' && matrix.node-version == 'v22.14.0'

test/performance/performance-test-helpers.ts

@@ -124,4 +124,46 @@ export function assertPerformance(
             `Errors ${result.errors} exceeds threshold ${thresholds.maxErrors}`
         );
     }
-}
+
+    testResults = result;
+}
+
+const PERF_LOGGING_API_KEY = process.env.POSTHOG_PERF_API_KEY;
+let testResults: PerformanceResult | undefined = undefined;
+beforeEach(() => {
+    testResults = undefined;
+});
+
+afterEach(async function () {
+    if (PERF_LOGGING_API_KEY) {
+        if (!this.currentTest) throw new Error("Can't log perf results without a test context");
+        if (this.currentTest.state !== 'passed') return;
+        if (!testResults) throw new Error("Can't log perf results without test results");
+
+        const testTitle = this.currentTest.fullTitle();
+
+        const result = await fetch("https://eu.i.posthog.com/capture/", {
+            method: "POST",
+            headers: {
+                "Content-Type": "application/json",
+            },
+            body: JSON.stringify({
+                api_key: PERF_LOGGING_API_KEY,
+                event: "performance_test_result",
+                distinct_id: `mockttp-${process.env.ImageOS || 'local'}`,
+                properties: {
+                    $process_person_profile: false,
+                    sha: process.env.GITHUB_SHA || 'local',
+                    test_name: "Mockttp - " + testTitle,
+                    throughput: testResults.throughput,
+                    mean_latency: testResults.latency.mean,
+                    p99_latency: testResults.latency.p99,
+                    errors: testResults.errors,
+
+                },
+            }),
+        });
+
+        expect(result.ok).to.equal(true, `Failed to log performance results: ${await result.text()}`);
+    }
+});

test/performance/performance-tests.perf.ts

@@ -7,7 +7,7 @@ import {
 } from "./performance-test-helpers";
 
 nodeOnly(() => {
-    describe("Performance tests", function() {
+    describe("Performance Tests:", function() {
         this.timeout(120000);
 
         describe("Static HTTP mocking", () => {