Cypress: Test that user can modify callbackWaitsForEmptyEventLoop

Test that users can modify the Netlify Function's
callbackWaitsForEmptyEventLoop behavior via the newly exposed function
event and context objects. When callbackWaitsForEmptyEventLoop is true
(default), the function does not finish until all async processes and
timeouts are completed (or cleared). The user can set this to false to
not wait for other processes to finish.

Author: FinnWoelm

cypress/fixtures/pages/getServerSideProps/wait-on-empty-event-loop/[wait].js

@@ -0,0 +1,17 @@
+const WaitForEmptyEventLoop = () => <p>Successfully rendered page!</p>;
+
+export const getServerSideProps = async ({ params, req }) => {
+  // Set up long-running process
+  const timeout = setTimeout(() => {}, 100000);
+
+  // Set behavior of whether to wait for empty event loop
+  const wait = String(params.wait).toLowerCase() === "true";
+  const { context: functionContext } = req.netlifyFunction;
+  functionContext.callbackWaitsForEmptyEventLoop = wait;
+
+  return {
+    props: {},
+  };
+};
+
+export default WaitForEmptyEventLoop;

cypress/integration/default_spec.js

@@ -161,6 +161,24 @@ describe("getServerSideProps", () => {
       });
   });
 
+  it("can modify the callbackWaitsForEmptyEventLoop behavior", () => {
+    // netlify dev never waits on empty event loop
+    if (Cypress.env("DEPLOY") !== "local") {
+      cy.request({
+        url: "/getServerSideProps/wait-on-empty-event-loop/true",
+        failOnStatusCode: false,
+        // Functions time out after 10s, so we need to wait a bit
+        timeout: 15000,
+      }).then((response) => {
+        expect(response.status).to.eq(502);
+        expect(response.body).to.contain("Task timed out");
+      });
+    }
+
+    cy.visit("/getServerSideProps/wait-on-empty-event-loop/false");
+    cy.get("p").should("contain", "Successfully rendered page!");
+  });
+
   context("with static route", () => {
     it("loads TV shows", () => {
       cy.visit("/getServerSideProps/static");