test(ssr): Fix flakes (#34443)

integration-tests/ssr/__tests__/ssr.js

@@ -33,7 +33,7 @@ describe(`SSR`, () => {
     expect(String(childProcess.stdout)).toContain(
       `testing these paths for differences between dev & prod outputs`
     )
-  }, 15000)
+  }, 30000)
 
   test(`it generates an error page correctly`, async () => {
     const src = path.join(__dirname, `/fixtures/bad-page.js`)

integration-tests/ssr/test-output.js

@@ -47,10 +47,10 @@ async function run() {
     // Fetch once to trigger re-compilation.
     await fetch(`${devSiteBasePath}/${path}`)
 
-    // Then wait for 6 seconds to ensure it's ready to go.
+    // Then wait for a second to ensure it's ready to go.
     // Otherwise, tests are flaky depending on the speed of the testing machine.
     await new Promise(resolve => {
-      setTimeout(() => resolve(), 6000)
+      setTimeout(() => resolve(), 1000)
     })
 
     let devStatus = 200
@@ -103,7 +103,15 @@ async function run() {
     paths
   )
 
-  const results = await Promise.all(paths.map(p => comparePath(p)))
+  const results = []
+
+  // Run comparisons serially, otherwise recompilation fetches
+  // interfere with each other when run within Promise.all
+  for (const path of paths) {
+    const result = await comparePath(path)
+    results.push(result)
+  }
+
   // Test all true
   if (results.every(r => r)) {
     process.exit(0)