test(integration): exercise graphql tracing channels on real node:diagnostics_channel

Adds an integrationTests/diagnostics/ project that installs the built
graphql package, registers node:diagnostics_channel, and asserts that
subscribers to graphql:parse receive the expected start/end/error
lifecycle events. Complements the unit tests (which use a FakeDc) with
coverage against a real TracingChannel.

The in-tree eslint rules forbid node: imports and flag TracingChannel as
experimental in src/; integrationTests/* overrides already allow the
node: import, and a file-scope disable handles the experimental warning.
The integration project pins engines to >=22 to match where graphql-js
v17 is actively tested.

This file grows as later channels (validate, execute, subscribe,
resolve) are wired up.

Author: logaretm

integrationTests/diagnostics/package.json

@@ -0,0 +1,14 @@
+{
+  "description": "graphql-js tracing channels should publish on node:diagnostics_channel",
+  "private": true,
+  "type": "module",
+  "engines": {
+    "node": ">=22.0.0"
+  },
+  "scripts": {
+    "test": "node test.js"
+  },
+  "dependencies": {
+    "graphql": "file:../graphql.tgz"
+  }
+}

integrationTests/diagnostics/test.js

@@ -0,0 +1,73 @@
+// TracingChannel is marked experimental in Node's docs but is shipped on
+// every runtime graphql-js supports. This test exercises it directly.
+/* eslint-disable n/no-unsupported-features/node-builtins */
+
+import assert from 'node:assert/strict';
+import dc from 'node:diagnostics_channel';
+
+import { enableDiagnosticsChannel, parse } from 'graphql';
+
+enableDiagnosticsChannel(dc);
+
+// graphql:parse - synchronous
+{
+  const events = [];
+  const handler = {
+    start: (msg) => events.push({ kind: 'start', source: msg.source }),
+    end: (msg) => events.push({ kind: 'end', source: msg.source }),
+    asyncStart: (msg) =>
+      events.push({ kind: 'asyncStart', source: msg.source }),
+    asyncEnd: (msg) => events.push({ kind: 'asyncEnd', source: msg.source }),
+    error: (msg) =>
+      events.push({ kind: 'error', source: msg.source, error: msg.error }),
+  };
+
+  const channel = dc.tracingChannel('graphql:parse');
+  channel.subscribe(handler);
+
+  try {
+    const doc = parse('{ field }');
+    assert.equal(doc.kind, 'Document');
+    assert.deepEqual(
+      events.map((e) => e.kind),
+      ['start', 'end'],
+    );
+    assert.equal(events[0].source, '{ field }');
+    assert.equal(events[1].source, '{ field }');
+  } finally {
+    channel.unsubscribe(handler);
+  }
+}
+
+// graphql:parse - error path fires start, error, end (traceSync finally-emits end)
+{
+  const events = [];
+  const handler = {
+    start: (msg) => events.push({ kind: 'start', source: msg.source }),
+    end: (msg) => events.push({ kind: 'end', source: msg.source }),
+    error: (msg) =>
+      events.push({ kind: 'error', source: msg.source, error: msg.error }),
+  };
+
+  const channel = dc.tracingChannel('graphql:parse');
+  channel.subscribe(handler);
+
+  try {
+    assert.throws(() => parse('{ '));
+    assert.deepEqual(
+      events.map((e) => e.kind),
+      ['start', 'error', 'end'],
+    );
+    assert.ok(events[1].error instanceof Error);
+  } finally {
+    channel.unsubscribe(handler);
+  }
+}
+
+// No-op when nothing is subscribed - parse still succeeds.
+{
+  const doc = parse('{ field }');
+  assert.equal(doc.kind, 'Document');
+}
+
+console.log('diagnostics integration test passed');

resources/integration-test.ts

@@ -55,6 +55,9 @@ describe('Integration Tests', () => {
   testOnNodeProject('node');
   testOnNodeProject('webpack');
 
+  // Tracing channel tests
+  testOnNodeProject('diagnostics');
+
   // Conditional export tests
   testOnNodeProject('conditions');