fix(incrementalDelivery): add additional tests

When a non-null list is streamed and completeValue for a list item
fails, the error should bubble up to the list itself and no further
payloads should be sent.

Addition of tests within this change demonstrates that this is currently
the case only when the field resolver for the list returns an iterable,
but not when it returns an async iterable. In the latter case, the null
correctly bubbles to the list itself for the given payload (`items:
null` rather than `items: [null`), but further payloads are sent.

Author: yaacovCR

src/execution/__tests__/stream-test.ts

@@ -1,4 +1,4 @@
-import { assert } from 'chai';
+import { assert, expect } from 'chai';
 import { describe, it } from 'mocha';
 
 import { expectJSON } from '../../__testUtils__/expectJSON.js';
@@ -851,6 +851,57 @@ describe('Execute: stream directive', () => {
     ]);
   });
   it('Handles async errors thrown by completeValue after initialCount is reached', async () => {
+    const document = parse(`
+      query { 
+        friendList @stream(initialCount: 1) {
+          nonNullName
+        }
+      }
+    `);
+    const result = await complete(document, {
+      friendList: () => [
+        Promise.resolve({ nonNullName: friends[0].name }),
+        Promise.resolve({
+          nonNullName: () => Promise.reject(new Error('Oops')),
+        }),
+        Promise.resolve({ nonNullName: friends[1].name }),
+      ],
+    });
+    expectJSON(result).toDeepEqual([
+      {
+        data: {
+          friendList: [{ nonNullName: 'Luke' }],
+        },
+        hasNext: true,
+      },
+      {
+        incremental: [
+          {
+            items: [null],
+            path: ['friendList', 1],
+            errors: [
+              {
+                message: 'Oops',
+                locations: [{ line: 4, column: 11 }],
+                path: ['friendList', 1, 'nonNullName'],
+              },
+            ],
+          },
+        ],
+        hasNext: true,
+      },
+      {
+        incremental: [
+          {
+            items: [{ nonNullName: 'Han' }],
+            path: ['friendList', 2],
+          },
+        ],
+        hasNext: false,
+      },
+    ]);
+  });
+  it('Handles async errors thrown by completeValue after initialCount is reached for a non-nullable list', async () => {
     const document = parse(`
       query { 
         nonNullFriendList @stream(initialCount: 1) {
@@ -946,6 +997,50 @@ describe('Execute: stream directive', () => {
       },
     ]);
   });
+  it('Handles async errors thrown by completeValue after initialCount is reached from async iterable for a non-nullable list', async () => {
+    const document = parse(`
+      query { 
+        nonNullFriendList @stream(initialCount: 1) {
+          nonNullName
+        }
+      }
+    `);
+    const result = await complete(document, {
+      async *nonNullFriendList() {
+        yield await Promise.resolve({ nonNullName: friends[0].name });
+        yield await Promise.resolve({
+          nonNullName: () => Promise.reject(new Error('Oops')),
+        });
+        yield await Promise.resolve({
+          nonNullName: friends[1].name,
+        }); /* c8 ignore start */
+      } /* c8 ignore stop */,
+    });
+    expectJSON(result).toDeepEqual([
+      {
+        data: {
+          nonNullFriendList: [{ nonNullName: 'Luke' }],
+        },
+        hasNext: true,
+      },
+      {
+        incremental: [
+          {
+            items: null,
+            path: ['nonNullFriendList', 1],
+            errors: [
+              {
+                message: 'Oops',
+                locations: [{ line: 4, column: 11 }],
+                path: ['nonNullFriendList', 1, 'nonNullName'],
+              },
+            ],
+          },
+        ],
+        hasNext: false,
+      },
+    ]);
+  });
   it('Filters payloads that are nulled', async () => {
     const document = parse(`
       query {