stop resolvers after execution ends

TODO: add support and tests for stopping within incremental delivery

addresses: #3792

src/execution/__tests__/abort-signal-test.ts

@@ -349,7 +349,7 @@ describe('Execute: Cancellation', () => {
     });
   });
 
-  it('should stop deferred execution when aborted mid-execution', async () => {
+  it('should stop deferred execution when aborted prior to initiation of deferred execution', async () => {
     const abortController = new AbortController();
     const document = parse(`
       query {
@@ -358,9 +358,7 @@ describe('Execute: Cancellation', () => {
           ... on Todo @defer {
             text
             author {
-              ... on Author @defer {
-                id
-              }
+              id
             }
           }
         }
@@ -428,6 +426,84 @@ describe('Execute: Cancellation', () => {
     ]);
   });
 
+  it('should stop deferred execution when aborted within deferred execution', async () => {
+    const abortController = new AbortController();
+    const document = parse(`
+      query {
+        ... on Query @defer {
+          todo {
+            id
+            text
+            author {
+              id
+            }
+          }
+        }
+      }
+    `);
+
+    const resultPromise = complete(
+      document,
+      {
+        todo: async () =>
+          Promise.resolve({
+            id: '1',
+            text: 'hello world',
+            author: async () =>
+              /* c8 ignore next 2 */
+              Promise.resolve({
+                id: () => expect.fail('Should not be called'),
+              }),
+          }),
+      },
+      abortController.signal,
+    );
+
+    await resolveOnNextTick();
+    await resolveOnNextTick();
+    await resolveOnNextTick();
+
+    abortController.abort();
+
+    const result = await resultPromise;
+
+    expectJSON(result).toDeepEqual([
+      {
+        data: {},
+        pending: [{ id: '0', path: [] }],
+        hasNext: true,
+      },
+      {
+        incremental: [
+          {
+            data: {
+              todo: {
+                id: '1',
+                text: 'hello world',
+                author: null,
+              },
+            },
+            errors: [
+              {
+                locations: [
+                  {
+                    column: 13,
+                    line: 7,
+                  },
+                ],
+                message: 'This operation was aborted',
+                path: ['todo', 'author'],
+              },
+            ],
+            id: '0',
+          },
+        ],
+        completed: [{ id: '0' }],
+        hasNext: false,
+      },
+    ]);
+  });
+
   it('should stop the execution when aborted mid-mutation', async () => {
     const abortController = new AbortController();
     const document = parse(`

src/execution/__tests__/nonnull-test.ts

@@ -2,6 +2,7 @@ import { expect } from 'chai';
 import { describe, it } from 'mocha';
 
 import { expectJSON } from '../../__testUtils__/expectJSON.js';
+import { resolveOnNextTick } from '../../__testUtils__/resolveOnNextTick.js';
 
 import type { PromiseOrValue } from '../../jsutils/PromiseOrValue.js';
 
@@ -526,6 +527,93 @@ describe('Execute: handles non-nullable types', () => {
     });
   });
 
+  describe('cancellation with null bubbling', () => {
+    function nestedPromise(n: number): string {
+      return n > 0 ? `promiseNest { ${nestedPromise(n - 1)} }` : 'promise';
+    }
+    it('returns both errors if insufficiently nested', async () => {
+      const query = `
+      {
+        promiseNonNull,
+        ${nestedPromise(3)}
+      }
+    `;
+
+      const result = await executeQuery(query, throwingData);
+      expectJSON(result).toDeepEqual({
+        data: null,
+        errors: [
+          {
+            message: 'promise',
+            path: ['promiseNest', 'promiseNest', 'promiseNest', 'promise'],
+            locations: [{ line: 4, column: 51 }],
+          },
+          {
+            message: 'promiseNonNull',
+            path: ['promiseNonNull'],
+            locations: [{ line: 3, column: 9 }],
+          },
+        ],
+      });
+    });
+
+    it('returns only a single error if sufficiently nested', async () => {
+      const query = `
+        {
+          promiseNonNull,
+          ${nestedPromise(4)}
+        }
+      `;
+
+      const result = await executeQuery(query, throwingData);
+      expectJSON(result).toDeepEqual({
+        data: null,
+        errors: [
+          // does not include syncNullError because result returns prior to it being added
+          {
+            message: 'promiseNonNull',
+            path: ['promiseNonNull'],
+            locations: [{ line: 3, column: 11 }],
+          },
+        ],
+      });
+    });
+
+    it('keeps running despite error', async () => {
+      const query = `
+        {
+          promiseNonNull,
+          ${nestedPromise(10)}
+        }
+      `;
+
+      let counter = 0;
+      const rootValue = {
+        ...throwingData,
+        promiseNest() {
+          return new Promise((resolve) => {
+            counter++;
+            resolve(rootValue);
+          });
+        },
+      };
+      const result = await executeQuery(query, rootValue);
+      expectJSON(result).toDeepEqual({
+        data: null,
+        errors: [
+          {
+            message: 'promiseNonNull',
+            path: ['promiseNonNull'],
+            locations: [{ line: 3, column: 11 }],
+          },
+        ],
+      });
+      const counterAtExecutionEnd = counter;
+      await resolveOnNextTick();
+      expect(counter).to.equal(counterAtExecutionEnd);
+    });
+  });
+
   describe('Handles non-null argument', () => {
     const schemaWithNonNullArg = new GraphQLSchema({
       query: new GraphQLObjectType({