Make mock response error and result optional when delay is infinite (#…

…11562)

.changeset/tiny-vans-draw.md

@@ -0,0 +1,5 @@
+---
+"@apollo/client": patch
+---
+
+Mocks with an infinite delay no longer require result or error

src/testing/core/mocking/__tests__/mockLink.ts

@@ -0,0 +1,64 @@
+import gql from "graphql-tag";
+import { MockLink } from "../mockLink";
+import { execute } from "../../../../link/core/execute";
+
+/*
+We've chosen this value as the MAXIMUM_DELAY since values that don't fit into a 32-bit signed int cause setTimeout to fire immediately
+*/
+const MAXIMUM_DELAY = 0x7f_ff_ff_ff;
+
+describe("mockLink", () => {
+  beforeAll(() => jest.useFakeTimers());
+  afterAll(() => jest.useRealTimers());
+
+  const query = gql`
+    query A {
+      a
+    }
+  `;
+
+  it("should not require a result or error when delay equals Infinity", async () => {
+    const mockLink = new MockLink([
+      {
+        request: {
+          query,
+        },
+        delay: Infinity,
+      },
+    ]);
+
+    const observable = execute(mockLink, { query });
+
+    const subscription = observable.subscribe(
+      () => fail("onNext was called"),
+      () => fail("onError was called"),
+      () => fail("onComplete was called")
+    );
+    jest.advanceTimersByTime(MAXIMUM_DELAY);
+    subscription.unsubscribe();
+  });
+
+  it("should require result or error when delay is just large", (done) => {
+    const mockLink = new MockLink([
+      {
+        request: {
+          query,
+        },
+        delay: MAXIMUM_DELAY,
+      },
+    ]);
+
+    execute(mockLink, { query }).subscribe(
+      () => fail("onNext was called"),
+      (error) => {
+        expect(error).toBeInstanceOf(Error);
+        expect(error.message).toMatch(
+          /^Mocked response should contain either `result`, `error` or a `delay` of `Infinity`: /
+        );
+        done();
+      }
+    );
+
+    jest.advanceTimersByTime(MAXIMUM_DELAY);
+  });
+});

src/testing/core/mocking/mockLink.ts

@@ -154,9 +154,9 @@ ${unmatchedVars.map((d) => `  ${stringifyForDisplay(d)}`).join("\n")}
         mockedResponses.push(response);
       }
 
-      if (!response.result && !response.error) {
+      if (!response.result && !response.error && response.delay !== Infinity) {
         configError = new Error(
-          `Mocked response should contain either result or error: ${key}`
+          `Mocked response should contain either \`result\`, \`error\` or a \`delay\` of \`Infinity\`: ${key}`
         );
       }
     }

src/testing/react/__tests__/__snapshots__/MockedProvider.test.tsx.snap

@@ -78,7 +78,7 @@ Object {
 
 exports[`General use should pipe exceptions thrown in custom onError functions through the link chain 1`] = `[ApolloError: oh no!]`;
 
-exports[`General use should return "Mocked response should contain" errors in response 1`] = `[ApolloError: Mocked response should contain either result or error: {"query":"query GetUser($username: String!) {\\n  user(username: $username) {\\n    id\\n    __typename\\n  }\\n}"}]`;
+exports[`General use should return "Mocked response should contain" errors in response 1`] = `[ApolloError: Mocked response should contain either \`result\`, \`error\` or a \`delay\` of \`Infinity\`: {"query":"query GetUser($username: String!) {\\n  user(username: $username) {\\n    id\\n    __typename\\n  }\\n}"}]`;
 
 exports[`General use should return "No more mocked responses" errors in response 1`] = `
 [ApolloError: No more mocked responses for the query: query GetUser($username: String!) {