Skip resource route flow in dev mode when SPA mode is enabled (#13113)

* Skip resource route flow in dev mode when SPA  mode is enabled

* Update tests to include proper ssr value on mocked builds

Author: brophdawg11

.changeset/cool-pillows-sing.md

@@ -0,0 +1,5 @@
+---
+"react-router": patch
+---
+
+Skip resource route flow in dev server in SPA mode

packages/react-router/__tests__/server-runtime/handler-test.ts

@@ -3,6 +3,7 @@ import { createRequestHandler } from "../../lib/server-runtime/server";
 describe("createRequestHandler", () => {
   it("retains request headers when stripping body off for loaders", async () => {
     let handler = createRequestHandler({
+      ssr: true,
       routes: {
         root: {
           id: "routes/test",

packages/react-router/__tests__/server-runtime/server-test.ts

@@ -27,6 +27,7 @@ function spyConsole() {
 describe.skip("server", () => {
   let routeId = "root";
   let build: ServerBuild = {
+    ssr: true,
     entry: {
       module: {
         default: async (request) => {

packages/react-router/__tests__/server-runtime/utils.ts

@@ -33,6 +33,7 @@ export function mockServerBuild(
   } = {}
 ) {
   return {
+    ssr: true,
     future: {
       ...opts.future,
     },

packages/react-router/lib/server-runtime/server.ts

@@ -250,6 +250,7 @@ export const createRequestHandler: CreateRequestHandlerFunction = (
         }
       }
     } else if (
+      !request.headers.has("X-React-Router-SPA-Mode") &&
       matches &&
       matches[matches.length - 1].route.module.default == null &&
       matches[matches.length - 1].route.module.ErrorBoundary == null