Implement functionally for "deprecate fetch" RFC

addon/src/index.ts

@@ -20,3 +20,4 @@ export {
 export { default as buildWaiter, _resetWaiterNames } from './build-waiter.ts';
 export { default as waitForPromise } from './wait-for-promise.ts';
 export { default as waitFor } from './wait-for.ts';
+export { waitForFetch } from './wait-for-fetch.ts';

addon/src/wait-for-fetch.ts

@@ -0,0 +1,22 @@
+import { default as waitForPromise } from './wait-for-promise.ts';
+
+export async function waitForFetch(fetchPromise: ReturnType<typeof fetch>) {
+  const response = await waitForPromise(fetchPromise);
+
+  return new Proxy(response, {
+    get(target, prop, receiver) {
+      const original = Reflect.get(target, prop, receiver);
+
+      if (
+        typeof prop === 'string' &&
+        ['json', 'text', 'arrayBuffer', 'blob', 'formData', 'bytes'].includes(prop)
+      ) {
+        return (...args: unknown[]) => {
+          return waitForPromise(original.call(target, ...args));
+        };
+      }
+
+      return original;
+    },
+  });
+}

test-apps/base-tests/package.json

@@ -91,7 +91,7 @@
     "webpack": "^5.96.1"
   },
   "engines": {
-    "node": "16.* || >= 18"
+    "node": ">= 18"
   },
   "ember": {
     "edition": "octane"

test-apps/base-tests/tests/unit/wait-for-fetch-test.ts

@@ -0,0 +1,188 @@
+import { module, test } from 'qunit';
+import { settled } from '@ember/test-helpers';
+import { waitForFetch, getPendingWaiterState } from '@ember/test-waiters';
+
+function expectWaiters(assert: Assert, expected: number) {
+  const result = getPendingWaiterState().pending;
+  assert.strictEqual(
+    result,
+    expected,
+    `Expecting ${expected} pending waiter(s)`,
+  );
+}
+
+function createFormData(obj: any) {
+  const data = new FormData();
+
+  for (const [k, v] of Object.entries(obj)) {
+    // SAFETY: just for testing, we can be a bit looser
+    data.append(k, v as string);
+  }
+
+  return data;
+}
+
+const supported = [
+  {
+    method: 'json',
+    input: new Response('{ "hi": "there" }'),
+    parsed: { hi: 'there' },
+  },
+  { method: 'text', input: new Response('text'), parsed: 'text' },
+  {
+    method: 'arrayBuffer',
+    input: new Response(new ArrayBuffer(8)),
+    parsed: new ArrayBuffer(8),
+  },
+  {
+    method: 'blob',
+    input: new Response(new Blob(['hi'])),
+    parsed: new Blob(['hi']),
+  },
+  {
+    method: 'formData',
+    input: new Response(createFormData({ x: 1 })),
+    parsed: createFormData({ x: 1 }),
+  },
+  {
+    method: 'bytes',
+    input: new Response(new Uint8Array([92])),
+    parsed: new Uint8Array([92]),
+  },
+] as const;
+
+module('waitForFetch', function () {
+  for (const scenario of supported) {
+    test(`[${scenario.method}] minimal`, async function (assert) {
+      const fetchish = new Promise<Response>((resolve) =>
+        resolve(scenario.input),
+      );
+      const requestPromise = waitForFetch(fetchish);
+
+      expectWaiters(assert, 1);
+      const response = await requestPromise;
+
+      expectWaiters(assert, 0);
+
+      const responsePromise = (response as any)[scenario.method]();
+      expectWaiters(assert, 1);
+
+      const verify = await responsePromise;
+      expectWaiters(assert, 0);
+
+      assert.deepEqual(
+        verify,
+        scenario.parsed,
+        // eslint-disable-next-line @typescript-eslint/no-base-to-string
+        `Expected: ${scenario.parsed.toString()}`,
+      );
+    });
+  }
+
+  test('timing: empty response', async function (assert) {
+    function stepPromise<T>(
+      assert: Assert,
+      label: string,
+      promise: Promise<T>,
+    ) {
+      return promise
+        .then((result) => {
+          assert.step(`${label}:then`);
+          return result;
+        })
+        .catch((e) => {
+          assert.step(`${label}:catch`);
+          return e;
+        });
+    }
+
+    function fetchLike(assert: Assert) {
+      const handlers = {} as {
+        resolve: <T>(r: T) => unknown;
+        reject: (e: unknown) => unknown;
+      };
+      const original = new Promise((resolve, reject) => {
+        assert.step('fetch:start');
+        handlers.resolve = resolve;
+        handlers.reject = reject;
+      });
+
+      const promise = stepPromise(assert, 'fetch', original);
+
+      return {
+        promise,
+        resolve(value: unknown) {
+          return handlers.resolve(value);
+        },
+        reject(e: unknown) {
+          return handlers.reject(e);
+        },
+      };
+    }
+
+    function proxiedResponse(assert: Assert, response: Response) {
+      return new Proxy(response, {
+        get(target, prop, receiver) {
+          const original = Reflect.get(target, prop, receiver);
+
+          if (
+            typeof prop === 'string' &&
+            [
+              'json',
+              'text',
+              'arrayBuffer',
+              'blob',
+              'formData',
+              'bytes',
+            ].includes(prop)
+          ) {
+            return (...args: unknown[]) => {
+              const label = `response:${prop}`;
+              // not part of waiting, but this tells us
+              // we proxied correctly
+              assert.step(label);
+              const promise = original.call(target, ...args);
+
+              return stepPromise(assert, label, promise);
+            };
+          }
+
+          return original;
+        },
+      });
+    }
+
+    const f = fetchLike(assert);
+
+    expectWaiters(assert, 0);
+    const requestPromise = waitForFetch(f.promise);
+
+    assert.verifySteps(['fetch:start']);
+    expectWaiters(assert, 1);
+
+    f.resolve(proxiedResponse(assert, new Response()));
+    assert.verifySteps([]);
+    expectWaiters(assert, 1);
+
+    await settled();
+    assert.verifySteps(['fetch:then'], `Nothing on the response accessed`);
+    assert.verifySteps([]);
+    expectWaiters(assert, 0);
+
+    const response = await requestPromise;
+    assert.verifySteps([]);
+    expectWaiters(assert, 0);
+
+    const responsePromise = response.text();
+    assert.verifySteps(['response:text']);
+    expectWaiters(assert, 1);
+
+    await settled();
+    assert.verifySteps(['response:text:then']);
+    expectWaiters(assert, 0);
+
+    await responsePromise;
+    assert.verifySteps([]);
+    expectWaiters(assert, 0);
+  });
+});