test(server): move tests out of src folder (#4366)

apps/server/tests/prometheus-metrics.spec.ts

@@ -0,0 +1,79 @@
+import { Test, TestingModule } from '@nestjs/testing';
+import test from 'ava';
+import { register } from 'prom-client';
+
+import { MetricsModule } from '../src/metrics';
+import { Metrics } from '../src/metrics/metrics';
+import { PrismaModule } from '../src/prisma';
+
+let metrics: Metrics;
+let module: TestingModule;
+
+test.beforeEach(async () => {
+  module = await Test.createTestingModule({
+    imports: [MetricsModule, PrismaModule],
+  }).compile();
+
+  metrics = module.get(Metrics);
+});
+
+test.afterEach.always(async () => {
+  await module.close();
+});
+
+test('should be able to increment counter', async t => {
+  metrics.socketIOEventCounter(1, { event: 'client-handshake' });
+  const socketIOCounterMetric =
+    await register.getSingleMetric('socket_io_counter');
+  t.truthy(socketIOCounterMetric);
+
+  t.truthy(
+    JSON.stringify((await socketIOCounterMetric!.get()).values) ===
+      '[{"value":1,"labels":{"event":"client-handshake"}}]'
+  );
+  t.pass();
+});
+
+test('should be able to timer', async t => {
+  let minimum: number;
+  {
+    const endTimer = metrics.socketIOEventTimer({ event: 'client-handshake' });
+    const a = performance.now();
+    await new Promise(resolve => setTimeout(resolve, 50));
+    const b = performance.now();
+    minimum = b - a;
+    endTimer();
+  }
+
+  let maximum: number;
+  {
+    const a = performance.now();
+    const endTimer = metrics.socketIOEventTimer({ event: 'client-handshake' });
+    await new Promise(resolve => setTimeout(resolve, 100));
+    endTimer();
+    const b = performance.now();
+    maximum = b - a;
+  }
+
+  const socketIOTimerMetric = register.getSingleMetric('socket_io_timer');
+  t.truthy(socketIOTimerMetric);
+
+  const observations = (await socketIOTimerMetric!.get()).values;
+
+  for (const observation of observations) {
+    if (
+      observation.labels.event === 'client-handshake' &&
+      'quantile' in observation.labels
+    ) {
+      t.truthy(
+        observation.value >= minimum / 1000,
+        'observation.value should be greater than minimum'
+      );
+      t.truthy(
+        observation.value <= maximum / 1000,
+        'observation.value should be less than maximum'
+      );
+    }
+  }
+  t.pass();
+});