test: add heap snapshot tests

Add a number of tests that validate that heap snapshots
contain what we expect them to contain, and cross-check
against a JS version of our own embedder graphs.

PR-URL: https://github.com/nodejs/node/pull/21741
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>

test/common/README.md

@@ -10,6 +10,7 @@ This directory contains modules used to test the Node.js implementation.
 * [DNS module](#dns-module)
 * [Duplex pair helper](#duplex-pair-helper)
 * [Fixtures module](#fixtures-module)
+* [Heap dump checker module](#heap-dump-checker-module)
 * [HTTP2 module](#http2-module)
 * [Internet module](#internet-module)
 * [tmpdir module](#tmpdir-module)
@@ -538,6 +539,42 @@ Returns the result of
 Returns the result of
 `fs.readFileSync(path.join(fixtures.fixturesDir, 'keys', arg), 'enc')`.
 
+## Heap dump checker module
+
+This provides utilities for checking the validity of heap dumps.
+This requires the usage of `--expose-internals`.
+
+### heap.recordState()
+
+Create a heap dump and an embedder graph copy for inspection.
+The returned object has a `validateSnapshotNodes` function similar to the
+one listed below. (`heap.validateSnapshotNodes(...)` is a shortcut for
+`heap.recordState().validateSnapshotNodes(...)`.)
+
+### heap.validateSnapshotNodes(name, expected, options)
+
+* `name` [<string>] Look for this string as the name of heap dump nodes.
+* `expected` [<Array>] A list of objects, possibly with an `children`
+  property that points to expected other adjacent nodes.
+* `options` [<Array>]
+  * `loose` [<boolean>] Do not expect an exact listing of occurrences
+    of nodes with name `name` in `expected`.
+
+Create a heap dump and an embedder graph copy and validate occurrences.
+
+<!-- eslint-disable no-undef, no-unused-vars, node-core/required-modules, strict -->
+```js
+validateSnapshotNodes('TLSWRAP', [
+  {
+    children: [
+      { name: 'enc_out' },
+      { name: 'enc_in' },
+      { name: 'TLSWrap' }
+    ]
+  }
+]);
+```
+
 ## HTTP/2 Module
 
 The http2.js module provides a handful of utilities for creating mock HTTP/2

test/common/heap.js

@@ -0,0 +1,80 @@
+/* eslint-disable node-core/required-modules */
+'use strict';
+const assert = require('assert');
+const util = require('util');
+
+let internalTestHeap;
+try {
+  internalTestHeap = require('internal/test/heap');
+} catch (e) {
+  console.log('using `test/common/heap.js` requires `--expose-internals`');
+  throw e;
+}
+const { createJSHeapDump, buildEmbedderGraph } = internalTestHeap;
+
+class State {
+  constructor() {
+    this.snapshot = createJSHeapDump();
+    this.embedderGraph = buildEmbedderGraph();
+  }
+
+  validateSnapshotNodes(name, expected, { loose = false } = {}) {
+    const snapshot = this.snapshot.filter(
+      (node) => node.name === 'Node / ' + name && node.type !== 'string');
+    if (loose)
+      assert(snapshot.length >= expected.length);
+    else
+      assert.strictEqual(snapshot.length, expected.length);
+    for (const expectedNode of expected) {
+      if (expectedNode.children) {
+        for (const expectedChild of expectedNode.children) {
+          const check = typeof expectedChild === 'function' ?
+            expectedChild :
+            (node) => [expectedChild.name, 'Node / ' + expectedChild.name]
+              .includes(node.name);
+
+          assert(snapshot.some((node) => {
+            return node.outgoingEdges.map((edge) => edge.toNode).some(check);
+          }), `expected to find child ${util.inspect(expectedChild)} ` +
+              `in ${util.inspect(snapshot)}`);
+        }
+      }
+    }
+
+    const graph = this.embedderGraph.filter((node) => node.name === name);
+    if (loose)
+      assert(graph.length >= expected.length);
+    else
+      assert.strictEqual(graph.length, expected.length);
+    for (const expectedNode of expected) {
+      if (expectedNode.edges) {
+        for (const expectedChild of expectedNode.children) {
+          const check = typeof expectedChild === 'function' ?
+            expectedChild : (node) => {
+              return node.name === expectedChild.name ||
+                (node.value &&
+                 node.value.constructor &&
+                 node.value.constructor.name === expectedChild.name);
+            };
+
+          assert(graph.some((node) => node.edges.some(check)),
+                 `expected to find child ${util.inspect(expectedChild)} ` +
+                 `in ${util.inspect(snapshot)}`);
+        }
+      }
+    }
+  }
+}
+
+function recordState() {
+  return new State();
+}
+
+function validateSnapshotNodes(...args) {
+  return recordState().validateSnapshotNodes(...args);
+}
+
+module.exports = {
+  recordState,
+  validateSnapshotNodes
+};

test/parallel/test-heapdump-dns.js

@@ -0,0 +1,17 @@
+// Flags: --expose-internals
+'use strict';
+require('../common');
+const { validateSnapshotNodes } = require('../common/heap');
+
+validateSnapshotNodes('DNSCHANNEL', []);
+const dns = require('dns');
+validateSnapshotNodes('DNSCHANNEL', [{}]);
+dns.resolve('localhost', () => {});
+validateSnapshotNodes('DNSCHANNEL', [
+  {
+    children: [
+      { name: 'task list' },
+      { name: 'ChannelWrap' }
+    ]
+  }
+]);

test/parallel/test-heapdump-fs-promise.js

@@ -0,0 +1,16 @@
+// Flags: --expose-internals
+'use strict';
+require('../common');
+const { validateSnapshotNodes } = require('../common/heap');
+const fs = require('fs').promises;
+
+validateSnapshotNodes('FSREQPROMISE', []);
+fs.stat(__filename);
+validateSnapshotNodes('FSREQPROMISE', [
+  {
+    children: [
+      { name: 'FSReqPromise' },
+      { name: 'Float64Array' }  // Stat array
+    ]
+  }
+]);

test/parallel/test-heapdump-http2.js

@@ -0,0 +1,76 @@
+// Flags: --expose-internals
+'use strict';
+const common = require('../common');
+const { recordState } = require('../common/heap');
+const http2 = require('http2');
+if (!common.hasCrypto)
+  common.skip('missing crypto');
+
+{
+  const state = recordState();
+  state.validateSnapshotNodes('HTTP2SESSION', []);
+  state.validateSnapshotNodes('HTTP2STREAM', []);
+}
+
+const server = http2.createServer();
+server.on('stream', (stream) => {
+  stream.respondWithFile(__filename);
+});
+server.listen(0, () => {
+  const client = http2.connect(`http://localhost:${server.address().port}`);
+  const req = client.request();
+
+  req.on('response', common.mustCall(() => {
+    const state = recordState();
+    state.validateSnapshotNodes('HTTP2STREAM', [
+      {
+        children: [
+          { name: 'Http2Stream' }
+        ]
+      },
+    ], { loose: true });
+    state.validateSnapshotNodes('FILEHANDLE', [
+      {
+        children: [
+          { name: 'FileHandle' }
+        ]
+      }
+    ]);
+    state.validateSnapshotNodes('TCPWRAP', [
+      {
+        children: [
+          { name: 'TCP' }
+        ]
+      }
+    ], { loose: true });
+    state.validateSnapshotNodes('TCPSERVERWRAP', [
+      {
+        children: [
+          { name: 'TCP' }
+        ]
+      }
+    ], { loose: true });
+    state.validateSnapshotNodes('STREAMPIPE', [
+      {
+        children: [
+          { name: 'StreamPipe' }
+        ]
+      }
+    ]);
+    state.validateSnapshotNodes('HTTP2SESSION', [
+      {
+        children: [
+          { name: 'Http2Session' },
+          { name: 'streams' }
+        ]
+      }
+    ], { loose: true });
+  }));
+
+  req.resume();
+  req.on('end', common.mustCall(() => {
+    client.close();
+    server.close();
+  }));
+  req.end();
+});

test/parallel/test-heapdump-inspector.js

@@ -0,0 +1,21 @@
+// Flags: --expose-internals
+'use strict';
+const common = require('../common');
+
+common.skipIfInspectorDisabled();
+
+const { validateSnapshotNodes } = require('../common/heap');
+const inspector = require('inspector');
+
+const session = new inspector.Session();
+validateSnapshotNodes('INSPECTORJSBINDING', []);
+session.connect();
+validateSnapshotNodes('INSPECTORJSBINDING', [
+  {
+    children: [
+      { name: 'session' },
+      { name: 'Connection' },
+      (node) => node.type === 'closure' || typeof node.value === 'function'
+    ]
+  }
+]);

test/parallel/test-heapdump-tls.js

@@ -0,0 +1,33 @@
+// Flags: --expose-internals
+'use strict';
+const common = require('../common');
+
+if (!common.hasCrypto)
+  common.skip('missing crypto');
+
+const { validateSnapshotNodes } = require('../common/heap');
+const net = require('net');
+const tls = require('tls');
+
+validateSnapshotNodes('TLSWRAP', []);
+
+const server = net.createServer(common.mustCall((c) => {
+  c.end();
+})).listen(0, common.mustCall(() => {
+  const c = tls.connect({ port: server.address().port });
+
+  c.on('error', common.mustCall(() => {
+    server.close();
+  }));
+  c.write('hello');
+
+  validateSnapshotNodes('TLSWRAP', [
+    {
+      children: [
+        { name: 'enc_out' },
+        { name: 'enc_in' },
+        { name: 'TLSWrap' }
+      ]
+    }
+  ]);
+}));

test/parallel/test-heapdump-worker.js

@@ -0,0 +1,27 @@
+// Flags: --expose-internals --experimental-worker
+'use strict';
+require('../common');
+const { validateSnapshotNodes } = require('../common/heap');
+const { Worker } = require('worker_threads');
+
+validateSnapshotNodes('WORKER', []);
+const worker = new Worker('setInterval(() => {}, 100);', { eval: true });
+validateSnapshotNodes('WORKER', [
+  {
+    children: [
+      { name: 'thread_exit_async' },
+      { name: 'env' },
+      { name: 'MESSAGEPORT' },
+      { name: 'Worker' }
+    ]
+  }
+]);
+validateSnapshotNodes('MESSAGEPORT', [
+  {
+    children: [
+      { name: 'data' },
+      { name: 'MessagePort' }
+    ]
+  }
+], { loose: true });
+worker.terminate();

test/parallel/test-heapdump-zlib.js

@@ -0,0 +1,17 @@
+// Flags: --expose-internals
+'use strict';
+require('../common');
+const { validateSnapshotNodes } = require('../common/heap');
+const zlib = require('zlib');
+
+validateSnapshotNodes('ZLIB', []);
+// eslint-disable-next-line no-unused-vars
+const gunzip = zlib.createGunzip();
+validateSnapshotNodes('ZLIB', [
+  {
+    children: [
+      { name: 'Zlib' },
+      { name: 'zlib memory' }
+    ]
+  }
+]);