Allow turbo streams for unprocessable entity responses

Since Rails can respond with 422 when form validation fails for example,
allow request.js to perform and render turbo stream messages for both
200 and 422 response codes.

Author: KirilSoshnin

__tests__/fetch_request.js

@@ -44,7 +44,7 @@ describe('perform', () => {
     })
   })
 
-  test('turbo stream request automatically calls renderTurboStream', async () => {
+  test('turbo stream request automatically calls renderTurboStream when status is ok', async () => {
     const mockResponse = new Response('', { status: 200, headers: { 'Content-Type': 'text/vnd.turbo-stream.html' }})
     window.fetch = jest.fn().mockResolvedValue(mockResponse)
     jest.spyOn(FetchResponse.prototype, "ok", "get").mockReturnValue(true)
@@ -55,6 +55,21 @@ describe('perform', () => {
     await testRequest.perform()
 
     expect(renderSpy).toHaveBeenCalledTimes(1)
+    jest.clearAllMocks();
+  })
+
+  test('turbo stream request automatically calls renderTurboStream when status is unprocessable entity', async () => {
+    const mockResponse = new Response('', { status: 422, headers: { 'Content-Type': 'text/vnd.turbo-stream.html' }})
+    window.fetch = jest.fn().mockResolvedValue(mockResponse)
+    jest.spyOn(FetchResponse.prototype, "ok", "get").mockReturnValue(true)
+    jest.spyOn(FetchResponse.prototype, "isTurboStream", "get").mockReturnValue(true)
+    const renderSpy = jest.spyOn(FetchResponse.prototype, "renderTurboStream").mockImplementation()
+
+    const testRequest = new FetchRequest("get", "localhost")
+    await testRequest.perform()
+
+    expect(renderSpy).toHaveBeenCalledTimes(1)
+    jest.clearAllMocks();
   })
 })
 

src/fetch_request.js

@@ -25,7 +25,9 @@ export class FetchRequest {
       return Promise.reject(window.location.href = response.authenticationURL)
     }
 
-    if (response.ok && response.isTurboStream) {
+    const responseStatusIsTurboStreamable = response.ok || response.unprocessableEntity
+
+    if (responseStatusIsTurboStreamable && response.isTurboStream) {
       await response.renderTurboStream()
     }