Add integration tests!

src/core/client/framework/lib/relay/index.ts

@@ -7,6 +7,7 @@ export { default as QueryRenderer } from "./QueryRenderer";
 export * from "./QueryRenderer";
 export { default as createMutationContainer } from "./createMutationContainer";
 export { default as createAndRetain } from "./createAndRetain";
+export { default as wrapFetchWithLogger } from "./wrapFetchWithLogger";
 export {
   commitMutationPromise,
   commitMutationPromiseNormalized,

src/core/client/framework/lib/relay/wrapFetchWithLogger.ts

@@ -0,0 +1,25 @@
+import { FetchFunction } from "relay-runtime";
+
+/**
+ * Decorates the fetch function with error logging.
+ * Intended for testing purposes.
+ */
+export default function wrapFetchWithLogger(
+  fetch: FetchFunction,
+  logResult?: boolean
+): FetchFunction {
+  return async (...args: any[]) => {
+    try {
+      const result = await (fetch as any)(...args);
+      if (logResult) {
+        // tslint:disable-next-line:no-console
+        console.log(JSON.stringify(result));
+      }
+      return result;
+    } catch (err) {
+      // tslint:disable-next-line:no-console
+      console.error(err);
+      throw err;
+    }
+  };
+}