feat: add tests for update.ts (#4835)

* feat: add isAddressInfo helper function

* feat(update): add test for rejection UpdateProvider

* feat: add more tests for UpdateProvider

* fixup! move isAddressInfo, add .address check

* fixup! remove extra writeHead

* fixup! use -1 in redirect logic

* fixup! remove unnecessary String call

* fixup! use /latest for redirect

* fixup! use match group for regex

* fixup!: replace match/split logic

test/utils/helpers.ts

@@ -105,3 +105,17 @@ export function idleTimer(message: string, reject: (error: Error) => void, delay
     },
   }
 }
+
+/**
+ * A helper function which returns a boolean indicating whether
+ * the given address is AddressInfo and has .address
+ * and a .port property.
+ */
+export function isAddressInfo(address: unknown): address is net.AddressInfo {
+  return (
+    address !== null &&
+    typeof address !== "string" &&
+    (address as net.AddressInfo).port !== undefined &&
+    (address as net.AddressInfo).address !== undefined
+  )
+}