fix: revert "fix: res.send of cy.intercept doesn't override json-…

…related content types. " (#17400)

This reverts commit c2a2206.

packages/driver/cypress/integration/commands/net_stubbing_spec.ts

@@ -2685,30 +2685,6 @@ describe('network stubbing', { retries: 2 }, function () {
       .wait('@get')
     })
 
-    // https://github.com/cypress-io/cypress/issues/17084
-    it('does not overwrite the json-related content-type header', () => {
-      cy.intercept('/json-content-type', (req) => {
-        req.on('response', (res) => {
-          res.send({
-            statusCode: 500,
-            headers: {
-              'content-type': 'application/problem+json',
-              'access-control-allow-origin': '*',
-            },
-            body: {
-              status: 500,
-              title: 'Internal Server Error',
-            },
-          })
-        })
-      })
-
-      fetch('/json-content-type')
-      .then((res) => {
-        expect(res.headers.get('content-type')).to.eq('application/problem+json')
-      })
-    })
-
     context('body parsing', function () {
       [
         'application/json',

packages/driver/src/cy/net-stubbing/events/response.ts

@@ -75,14 +75,7 @@ export const onResponse: HandlerFn<CyHttpMessages.IncomingResponse> = async (Cyp
         // arguments to res.send() are merged with the existing response
         const _staticResponse = _.defaults({}, staticResponse, _.pick(res, STATIC_RESPONSE_KEYS))
 
-        _staticResponse.headers = _.defaults({}, _staticResponse.headers, res.headers)
-
-        // https://github.com/cypress-io/cypress/issues/17084
-        // When a user didn't provide content-type,
-        // we remove the content-type provided by the server
-        if (!staticResponse.headers || !staticResponse.headers['content-type']) {
-          delete _staticResponse.headers['content-type']
-        }
+        _.defaults(_staticResponse.headers, res.headers)
 
         sendStaticResponse(requestId, _staticResponse)
 

packages/driver/src/cy/net-stubbing/static-response-utils.ts

@@ -5,9 +5,6 @@ import {
   BackendStaticResponseWithArrayBuffer,
   FixtureOpts,
 } from '@packages/net-stubbing/lib/types'
-import {
-  caseInsensitiveHas,
-} from '@packages/net-stubbing/lib/util'
 import $errUtils from '../../cypress/error_utils'
 
 // user-facing StaticResponse only
@@ -115,16 +112,7 @@ export function getBackendStaticResponse (staticResponse: Readonly<StaticRespons
       backendStaticResponse.body = staticResponse.body
     } else {
       backendStaticResponse.body = JSON.stringify(staticResponse.body)
-
-      // There are various json-related MIME types. We cannot simply set it as `application/json`.
-      // @see https://www.iana.org/assignments/media-types/media-types.xhtml
-      if (
-        !backendStaticResponse.headers ||
-        (backendStaticResponse.headers &&
-          !caseInsensitiveHas(backendStaticResponse.headers, 'content-type'))
-      ) {
-        _.set(backendStaticResponse, 'headers.content-type', 'application/json')
-      }
+      _.set(backendStaticResponse, 'headers.content-type', 'application/json')
     }
   }
 

packages/net-stubbing/lib/server/util.ts

@@ -16,7 +16,6 @@ import ThrottleStream from 'throttle'
 import MimeTypes from 'mime-types'
 import { CypressIncomingRequest } from '@packages/proxy'
 import { InterceptedRequest } from './intercepted-request'
-import { caseInsensitiveGet, caseInsensitiveHas } from '../util'
 
 // TODO: move this into net-stubbing once cy.route is removed
 import { parseContentType } from '@packages/server/lib/controllers/xhrs'
@@ -80,6 +79,24 @@ function _getFakeClientResponse (opts: {
   return clientResponse
 }
 
+const caseInsensitiveGet = function (obj, lowercaseProperty) {
+  for (let key of Object.keys(obj)) {
+    if (key.toLowerCase() === lowercaseProperty) {
+      return obj[key]
+    }
+  }
+}
+
+const caseInsensitiveHas = function (obj, lowercaseProperty) {
+  for (let key of Object.keys(obj)) {
+    if (key.toLowerCase() === lowercaseProperty) {
+      return true
+    }
+  }
+
+  return false
+}
+
 export function setDefaultHeaders (req: CypressIncomingRequest, res: IncomingMessage) {
   const setDefaultHeader = (lowercaseHeader: string, defaultValueFn: () => string) => {
     if (!caseInsensitiveHas(res.headers, lowercaseHeader)) {