do not emit pending for empty non-published subsequent results

The publish method checks to see if a subsequent result is empty; this same logic should be employed to suppress pending notices for empty records.

This has already been achieved for subsequent results that are children of the initial result, as we generated the pending notices from the list of initially published records.

For subsequent results that are children of other subsequent results, we previously generated the pending notice prior to actually publishing.

This change integrates the logic: the publishing method itself returns a pending notice as required. This results in a bug-fix for subsequent records of other subsequent records as well as a reduction of code for subsequent results to the initial result.

Author: yaacovCR

src/execution/IncrementalPublisher.ts

@@ -301,25 +301,20 @@ export class IncrementalPublisher {
     initialResultRecord: InitialResultRecord,
     data: ObjMap<unknown> | null,
   ): ExecutionResult | ExperimentalIncrementalExecutionResults {
+    const pendingSources = new Set<DeferredFragmentRecord | StreamRecord>();
     for (const child of initialResultRecord.children) {
       if (child.filtered) {
         continue;
       }
-      this._publish(child);
+      const maybePendingSource = this._publish(child);
+      if (maybePendingSource) {
+        pendingSources.add(maybePendingSource);
+      }
     }
 
     const errors = initialResultRecord.errors;
     const initialResult = errors.length === 0 ? { data } : { errors, data };
-    const pending = this._pending;
-    if (pending.size > 0) {
-      const pendingSources = new Set<DeferredFragmentRecord | StreamRecord>();
-      for (const subsequentResultRecord of pending) {
-        const pendingSource = isStreamItemsRecord(subsequentResultRecord)
-          ? subsequentResultRecord.streamRecord
-          : subsequentResultRecord;
-        pendingSources.add(pendingSource);
-      }
-
+    if (pendingSources.size > 0) {
       return {
         initialResult: {
           ...initialResult,
@@ -542,13 +537,10 @@ export class IncrementalPublisher {
         if (child.filtered) {
           continue;
         }
-        const pendingSource = isStreamItemsRecord(child)
-          ? child.streamRecord
-          : child;
-        if (!pendingSource.pendingSent) {
-          newPendingSources.add(pendingSource);
+        const maybePendingSource = this._publish(child);
+        if (maybePendingSource) {
+          newPendingSources.add(maybePendingSource);
         }
-        this._publish(child);
       }
       if (isStreamItemsRecord(subsequentResultRecord)) {
         if (subsequentResultRecord.isFinalRecord) {
@@ -655,15 +647,18 @@ export class IncrementalPublisher {
     return result;
   }
 
-  private _publish(subsequentResultRecord: SubsequentResultRecord): void {
+  private _publish(
+    subsequentResultRecord: SubsequentResultRecord,
+  ): DeferredFragmentRecord | StreamRecord | undefined {
     if (isStreamItemsRecord(subsequentResultRecord)) {
       if (subsequentResultRecord.isCompleted) {
         this._push(subsequentResultRecord);
-        return;
+      } else {
+        this._introduce(subsequentResultRecord);
       }
 
-      this._introduce(subsequentResultRecord);
-      return;
+      const stream = subsequentResultRecord.streamRecord;
+      return stream.pendingSent ? undefined : stream;
     }
 
     if (subsequentResultRecord._pending.size > 0) {
@@ -673,7 +668,13 @@ export class IncrementalPublisher {
       subsequentResultRecord.children.size > 0
     ) {
       this._push(subsequentResultRecord);
+    } else {
+      return;
     }
+
+    return subsequentResultRecord.pendingSent
+      ? undefined
+      : subsequentResultRecord;
   }
 
   private _getChildren(

src/execution/__tests__/defer-test.ts

@@ -64,6 +64,7 @@ const anotherNestedObject = new GraphQLObjectType({
 
 const hero = {
   name: 'Luke',
+  lastName: 'SkyWalker',
   id: 1,
   friends,
   nestedObject,
@@ -112,6 +113,7 @@ const heroType = new GraphQLObjectType({
   fields: {
     id: { type: GraphQLID },
     name: { type: GraphQLString },
+    lastName: { type: GraphQLString },
     nonNullName: { type: new GraphQLNonNull(GraphQLString) },
     friends: {
       type: new GraphQLList(friendType),
@@ -566,6 +568,58 @@ describe('Execute: defer directive', () => {
     ]);
   });
 
+  it('Separately emits defer fragments with different labels with varying subfields with superimposed masked defer', async () => {
+    const document = parse(`
+      query HeroNameQuery {
+        ... @defer(label: "DeferID") {
+          hero {
+            id
+          }
+        }
+        ... @defer(label: "DeferName") {
+          hero {
+            name
+            lastName
+            ... @defer {
+              lastName
+            }
+          }
+        }
+      }
+    `);
+    const result = await complete(document);
+    expectJSON(result).toDeepEqual([
+      {
+        data: {},
+        pending: [
+          { id: '0', path: [], label: 'DeferID' },
+          { id: '1', path: [], label: 'DeferName' },
+        ],
+        hasNext: true,
+      },
+      {
+        incremental: [
+          {
+            data: { hero: {} },
+            id: '0',
+          },
+          {
+            data: { id: '1' },
+            id: '0',
+            subPath: ['hero'],
+          },
+          {
+            data: { name: 'Luke', lastName: 'SkyWalker' },
+            id: '1',
+            subPath: ['hero'],
+          },
+        ],
+        completed: [{ id: '0' }, { id: '1' }],
+        hasNext: false,
+      },
+    ]);
+  });
+
   it('Separately emits defer fragments with different labels with varying subfields that return promises', async () => {
     const document = parse(`
       query HeroNameQuery {