test: Make N-API weak-ref GC tests asynchronous

One of the N-API weak-reference test cases already had to be made
asynchronous to handle different behavior in a newer V8 version:
#12864
When porting N-API to Node-ChakraCore, we found more of the test
cases needed similar treatment:
nodejs/node-chakracore#246 So to make
thes tests more robust (and avoid having differences in the test code
for Node-ChakraCore), I am refactoring the tests in this file to
insert a `setImmedate()` callback before every call to `gc()` and
assertions about the effects of the GC.

PR-URL: #13121
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

test/addons-napi/test_reference/test.js

@@ -11,80 +11,110 @@ const test_reference = require(`./build/${common.buildType}/test_reference`);
 // of a finalizer callback increments the finalizeCount property.
 assert.strictEqual(test_reference.finalizeCount, 0);
 
-{
-  // External value without a finalizer
-  let value = test_reference.createExternal();
-  assert.strictEqual(test_reference.finalizeCount, 0);
-  assert.strictEqual(typeof value, 'object');
-  test_reference.checkExternal(value);
-  value = null;
-  global.gc();
-  assert.strictEqual(test_reference.finalizeCount, 0);
+// Run each test function in sequence,
+// with an async delay and GC call between each.
+function runTests(i, title, tests) {
+  if (tests[i]) {
+    if (typeof tests[i] === 'string') {
+      title = tests[i];
+      runTests(i + 1, title, tests);
+    } else {
+      try {
+        tests[i]();
+      } catch (e) {
+        console.error('Test failed: ' + title);
+        throw e;
+      }
+      setImmediate(() => {
+        global.gc();
+        runTests(i + 1, title, tests);
+      });
+    }
+  }
 }
+runTests(0, undefined, [
 
-{
-  // External value with a finalizer
-  let value = test_reference.createExternalWithFinalize();
-  assert.strictEqual(test_reference.finalizeCount, 0);
-  assert.strictEqual(typeof value, 'object');
-  test_reference.checkExternal(value);
-  value = null;
-  global.gc();
-  assert.strictEqual(test_reference.finalizeCount, 1);
-}
-
-{
-  // Strong reference
-  let value = test_reference.createExternalWithFinalize();
-  assert.strictEqual(test_reference.finalizeCount, 0);
-  test_reference.createReference(value, 1);
-  assert.strictEqual(test_reference.referenceValue, value);
-  value = null;
-  global.gc(); // Value should NOT be GC'd because there is a strong ref
-  assert.strictEqual(test_reference.finalizeCount, 0);
-  test_reference.deleteReference();
-  global.gc(); // Value should be GC'd because the strong ref was deleted
-  assert.strictEqual(test_reference.finalizeCount, 1);
-}
-
-{
-  // Strong reference, increment then decrement to weak reference
-  let value = test_reference.createExternalWithFinalize();
-  assert.strictEqual(test_reference.finalizeCount, 0);
-  test_reference.createReference(value, 1);
-  value = null;
-  global.gc(); // Value should NOT be GC'd because there is a strong ref
-  assert.strictEqual(test_reference.finalizeCount, 0);
+  'External value without a finalizer',
+  () => {
+    const value = test_reference.createExternal();
+    assert.strictEqual(test_reference.finalizeCount, 0);
+    assert.strictEqual(typeof value, 'object');
+    test_reference.checkExternal(value);
+  },
+  () => {
+    assert.strictEqual(test_reference.finalizeCount, 0);
+  },
 
-  assert.strictEqual(test_reference.incrementRefcount(), 2);
-  global.gc(); // Value should NOT be GC'd because there is a strong ref
-  assert.strictEqual(test_reference.finalizeCount, 0);
-
-  assert.strictEqual(test_reference.decrementRefcount(), 1);
-  global.gc(); // Value should NOT be GC'd because there is a strong ref
-  assert.strictEqual(test_reference.finalizeCount, 0);
+  'External value with a finalizer',
+  () => {
+    const value = test_reference.createExternalWithFinalize();
+    assert.strictEqual(test_reference.finalizeCount, 0);
+    assert.strictEqual(typeof value, 'object');
+    test_reference.checkExternal(value);
+  },
+  () => {
+    assert.strictEqual(test_reference.finalizeCount, 1);
+  },
 
-  assert.strictEqual(test_reference.decrementRefcount(), 0);
-  global.gc(); // Value should be GC'd because the ref is now weak!
-  assert.strictEqual(test_reference.finalizeCount, 1);
+  'Weak reference',
+  () => {
+    const value = test_reference.createExternalWithFinalize();
+    assert.strictEqual(test_reference.finalizeCount, 0);
+    test_reference.createReference(value, 0);
+    assert.strictEqual(test_reference.referenceValue, value);
+  },
+  () => {
+    // Value should be GC'd because there is only a weak ref
+    assert.strictEqual(test_reference.referenceValue, undefined);
+    assert.strictEqual(test_reference.finalizeCount, 1);
+    test_reference.deleteReference();
+  },
 
-  test_reference.deleteReference();
-  global.gc(); // Value was already GC'd
-  assert.strictEqual(test_reference.finalizeCount, 1);
-}
+  'Strong reference',
+  () => {
+    const value = test_reference.createExternalWithFinalize();
+    assert.strictEqual(test_reference.finalizeCount, 0);
+    test_reference.createReference(value, 1);
+    assert.strictEqual(test_reference.referenceValue, value);
+  },
+  () => {
+    // Value should NOT be GC'd because there is a strong ref
+    assert.strictEqual(test_reference.finalizeCount, 0);
+    test_reference.deleteReference();
+  },
+  () => {
+    // Value should be GC'd because the strong ref was deleted
+    assert.strictEqual(test_reference.finalizeCount, 1);
+  },
 
-{
-  // Weak reference
-  let value = test_reference.createExternalWithFinalize();
-  assert.strictEqual(test_reference.finalizeCount, 0);
-  test_reference.createReference(value, 0);
-  assert.strictEqual(test_reference.referenceValue, value);
-  value = null;
-  setImmediate(common.mustCall(() => {
-    // This test only works if gc() is called from an immediate callback.
-    global.gc(); // Value should be GC'd because there is only a weak ref
-    assert.strictEqual(test_reference.referenceValue, undefined);
+  'Strong reference, increment then decrement to weak reference',
+  () => {
+    const value = test_reference.createExternalWithFinalize();
+    assert.strictEqual(test_reference.finalizeCount, 0);
+    test_reference.createReference(value, 1);
+  },
+  () => {
+    // Value should NOT be GC'd because there is a strong ref
+    assert.strictEqual(test_reference.finalizeCount, 0);
+    assert.strictEqual(test_reference.incrementRefcount(), 2);
+  },
+  () => {
+    // Value should NOT be GC'd because there is a strong ref
+    assert.strictEqual(test_reference.finalizeCount, 0);
+    assert.strictEqual(test_reference.decrementRefcount(), 1);
+  },
+  () => {
+    // Value should NOT be GC'd because there is a strong ref
+    assert.strictEqual(test_reference.finalizeCount, 0);
+    assert.strictEqual(test_reference.decrementRefcount(), 0);
+  },
+  () => {
+    // Value should be GC'd because the ref is now weak!
     assert.strictEqual(test_reference.finalizeCount, 1);
     test_reference.deleteReference();
-  }));
-}
+  },
+  () => {
+    // Value was already GC'd
+    assert.strictEqual(test_reference.finalizeCount, 1);
+  },
+]);