fix: Move content into to frontend directory

Doing this BEFORE the merge prevents a lot of merge conflicts.

Signed-off-by: Tilman Vatteroth <git@tilmanvatteroth.de>

frontend/src/handler-utils/respond-to-matching-request.ts

@@ -0,0 +1,46 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import type { NextApiRequest, NextApiResponse } from 'next'
+import { isMockMode } from '../utils/test-modes'
+
+export enum HttpMethod {
+  GET = 'GET',
+  POST = 'POST',
+  PUT = 'PUT',
+  DELETE = 'DELETE'
+}
+
+/**
+ * Intercepts a mock HTTP request, checks the used request method and responds with given response content or an error
+ * that the request method is not allowed.
+ *
+ * @param method The expected HTTP method.
+ * @param req The request object.
+ * @param res The response object.
+ * @param response The response data that will be returned when the HTTP method was the expected one.
+ * @param statusCode The status code with which the response will be sent.
+ * @return {@link true} if the HTTP method of the request is the expected one, {@link false} otherwise.
+ */
+export const respondToMatchingRequest = <T>(
+  method: HttpMethod,
+  req: NextApiRequest,
+  res: NextApiResponse,
+  response: T,
+  statusCode = 200
+): boolean => {
+  if (!isMockMode) {
+    res.status(404).send('Mock API is disabled')
+    return false
+  }
+  if (method !== req.method) {
+    res.status(405).send('Method not allowed')
+    return false
+  } else {
+    res.status(statusCode).json(response)
+    return true
+  }
+}