test: move common.onGC to individual module

Incrementally making `require('../common')` less of a monolith.
Move the `common.onGC()` utility to a separate standalone module
that is only imported when it's actually needed.

PR-URL: #22446
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Weijia Wang <starkwang@126.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

Author: jasnell

test/common/README.md

@@ -296,21 +296,6 @@ otherwise.
 ### noWarnCode
 See `common.expectWarning()` for usage.
 
-### onGC(target, listener)
-* `target` [<Object>]
-* `listener` [<Object>]
-  * `ongc` [<Function>]
-
-Installs a GC listener for the collection of `target`.
-
-This uses `async_hooks` for GC tracking. This means that it enables
-`async_hooks` tracking, which may affect the test functionality. It also
-means that between a `global.gc()` call and the listener being invoked
-a full `setImmediate()` invocation passes.
-
-`listener` is an object to make it easier to use a closure; the target object
-should not be in scope when `listener.ongc()` is created.
-
 ### opensslCli
 * [<boolean>]
 
@@ -759,6 +744,34 @@ via `NODE_TEST_*` environment variables. For example, to configure
 `internet.addresses.INET_HOST`, set the environment
 variable `NODE_TEST_INET_HOST` to a specified host.
 
+## ongc Module
+
+The `ongc` module allows a garbage collection listener to be installed. The
+module exports a single `onGC()` function.
+
+```js
+require('../common');
+const onGC = require('../common/ongc');
+
+onGC({}, { ongc() { console.log('collected'); } });
+```
+
+### onGC(target, listener)
+* `target` [<Object>]
+* `listener` [<Object>]
+  * `ongc` [<Function>]
+
+Installs a GC listener for the collection of `target`.
+
+This uses `async_hooks` for GC tracking. This means that it enables
+`async_hooks` tracking, which may affect the test functionality. It also
+means that between a `global.gc()` call and the listener being invoked
+a full `setImmediate()` invocation passes.
+
+`listener` is an object to make it easier to use a closure; the target object
+should not be in scope when `listener.ongc()` is created.
+
+
 ## tmpdir Module
 
 The `tmpdir` module supports the use of a temporary directory for testing.

test/common/index.js

@@ -805,30 +805,3 @@ exports.isCPPSymbolsNotMapped = exports.isWindows ||
                                 exports.isAIX ||
                                 exports.isLinuxPPCBE ||
                                 exports.isFreeBSD;
-
-const gcTrackerMap = new WeakMap();
-const gcTrackerTag = 'NODE_TEST_COMMON_GC_TRACKER';
-
-exports.onGC = function(obj, gcListener) {
-  const async_hooks = require('async_hooks');
-
-  const onGcAsyncHook = async_hooks.createHook({
-    init: exports.mustCallAtLeast(function(id, type, trigger, resource) {
-      if (this.trackedId === undefined) {
-        assert.strictEqual(type, gcTrackerTag);
-        this.trackedId = id;
-      }
-    }),
-    destroy(id) {
-      assert.notStrictEqual(this.trackedId, -1);
-      if (id === this.trackedId) {
-        this.gcListener.ongc();
-        onGcAsyncHook.disable();
-      }
-    }
-  }).enable();
-  onGcAsyncHook.gcListener = gcListener;
-
-  gcTrackerMap.set(obj, new async_hooks.AsyncResource(gcTrackerTag));
-  obj = null;
-};

test/common/ongc.js

@@ -0,0 +1,32 @@
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+const gcTrackerMap = new WeakMap();
+const gcTrackerTag = 'NODE_TEST_COMMON_GC_TRACKER';
+
+function onGC(obj, gcListener) {
+  const async_hooks = require('async_hooks');
+
+  const onGcAsyncHook = async_hooks.createHook({
+    init: common.mustCallAtLeast(function(id, type) {
+      if (this.trackedId === undefined) {
+        assert.strictEqual(type, gcTrackerTag);
+        this.trackedId = id;
+      }
+    }),
+    destroy(id) {
+      assert.notStrictEqual(this.trackedId, -1);
+      if (id === this.trackedId) {
+        this.gcListener.ongc();
+        onGcAsyncHook.disable();
+      }
+    }
+  }).enable();
+  onGcAsyncHook.gcListener = gcListener;
+
+  gcTrackerMap.set(obj, new async_hooks.AsyncResource(gcTrackerTag));
+  obj = null;
+}
+
+module.exports = onGC;

test/parallel/test-common-gc.js

@@ -1,15 +1,14 @@
 'use strict';
 // Flags: --expose-gc
 const common = require('../common');
+const onGC = require('../common/ongc');
 
 {
-  const gcListener = { ongc: common.mustCall() };
-  common.onGC({}, gcListener);
+  onGC({}, { ongc: common.mustCall() });
   global.gc();
 }
 
 {
-  const gcListener = { ongc: common.mustNotCall() };
-  common.onGC(process, gcListener);
+  onGC(process, { ongc: common.mustNotCall() });
   global.gc();
 }

test/parallel/test-gc-http-client-connaborted.js

@@ -3,7 +3,8 @@
 // just like test-gc-http-client.js,
 // but aborting every connection that comes in.
 
-const common = require('../common');
+require('../common');
+const onGC = require('../common/ongc');
 
 function serverHandler(req, res) {
   res.connection.destroy();
@@ -36,7 +37,7 @@ function getall() {
     }, cb).on('error', cb);
 
     count++;
-    common.onGC(req, { ongc });
+    onGC(req, { ongc });
   })();
 
   setImmediate(getall);

test/parallel/test-gc-http-client-onerror.js

@@ -3,7 +3,8 @@
 // just like test-gc-http-client.js,
 // but with an on('error') handler that does nothing.
 
-const common = require('../common');
+require('../common');
+const onGC = require('../common/ongc');
 
 function serverHandler(req, res) {
   req.resume();
@@ -42,7 +43,7 @@ function getall() {
     }, cb).on('error', onerror);
 
     count++;
-    common.onGC(req, { ongc });
+    onGC(req, { ongc });
   })();
 
   setImmediate(getall);

test/parallel/test-gc-http-client-timeout.js

@@ -3,7 +3,8 @@
 // just like test-gc-http-client.js,
 // but with a timeout set
 
-const common = require('../common');
+require('../common');
+const onGC = require('../common/ongc');
 
 function serverHandler(req, res) {
   setTimeout(function() {
@@ -45,7 +46,7 @@ function getall() {
     });
 
     count++;
-    common.onGC(req, { ongc });
+    onGC(req, { ongc });
   })();
 
   setImmediate(getall);

test/parallel/test-gc-http-client.js

@@ -3,6 +3,7 @@
 // just a simple http server and client.
 
 const common = require('../common');
+const onGC = require('../common/ongc');
 
 function serverHandler(req, res) {
   res.writeHead(200, { 'Content-Type': 'text/plain' });
@@ -34,7 +35,7 @@ function getall() {
   }, cb);
 
   count++;
-  common.onGC(req, { ongc });
+  onGC(req, { ongc });
 
   setImmediate(getall);
 }

test/parallel/test-gc-net-timeout.js

@@ -3,7 +3,8 @@
 // just like test-gc-http-client-timeout.js,
 // but using a net server/client instead
 
-const common = require('../common');
+require('../common');
+const onGC = require('../common/ongc');
 
 function serverHandler(sock) {
   sock.setTimeout(120000);
@@ -44,7 +45,7 @@ function getall() {
   });
 
   count++;
-  common.onGC(req, { ongc });
+  onGC(req, { ongc });
 
   setImmediate(getall);
 }

test/parallel/test-net-connect-memleak.js

@@ -23,6 +23,7 @@
 // Flags: --expose-gc
 
 const common = require('../common');
+const onGC = require('../common/ongc');
 const assert = require('assert');
 const net = require('net');
 
@@ -36,7 +37,7 @@ const gcListener = { ongc() { collected = true; } };
 
 {
   const gcObject = {};
-  common.onGC(gcObject, gcListener);
+  onGC(gcObject, gcListener);
 
   const sock = net.createConnection(
     server.address().port,