fix(spec): render response body for non-200 responses

src/core/plugins/spec/actions.js

@@ -1,7 +1,6 @@
 import YAML, { JSON_SCHEMA } from "js-yaml"
 import { Map as ImmutableMap } from "immutable"
 import parseUrl from "url-parse"
-import { serializeError } from "serialize-error"
 import isString from "lodash/isString"
 import debounce from "lodash/debounce"
 import set from "lodash/set"
@@ -482,7 +481,7 @@ export const executeRequest = (req) =>
             err.message = "**Failed to fetch.**  \n**Possible Reasons:** \n  - CORS \n  - Network Failure \n  - URL scheme must be \"http\" or \"https\" for CORS request."
           }
           specActions.setResponse(req.pathName, req.method, {
-            error: true, err: serializeError(err)
+            error: true, err
           })
         }
       )

src/core/plugins/spec/reducers.js

@@ -123,8 +123,8 @@ export default {
     let newState = state.setIn( [ "responses", path, method ], fromJSOrdered(result) )
 
     // ImmutableJS messes up Blob. Needs to reset its value.
-    if (win.Blob && res.data instanceof win.Blob) {
-      newState = newState.setIn( [ "responses", path, method, "text" ], res.data)
+    if (win.Blob && result.data instanceof win.Blob) {
+      newState = newState.setIn( [ "responses", path, method, "text" ], result.data)
     }
     return newState
   },

test/e2e-cypress/e2e/features/try-it-out-non-200-response-body.cy.js

@@ -0,0 +1,26 @@
+/**
+ * @prettier
+ */
+describe("#9556: SwaggerUI doesn't render response bodies for non-200 responses", () => {
+  beforeEach(() => {
+    const staticResponse = {
+      statusCode: 400,
+      headers: { "content-type": "plain/text" },
+      body: "This should render",
+    }
+    cy.intercept("GET", "/400-any", staticResponse).as("request")
+  })
+
+  it("should render response body for a response with 400 status code", () => {
+    cy.visit("?url=/documents/features/try-it-out-non-200-response-body.yaml")
+      .get("#operations-default-get_400_any")
+      .click()
+      .get(".try-out__btn")
+      .click()
+      .get(".execute")
+      .click()
+      .wait("@request")
+      .get(".response-col_description .highlight-code .microlight")
+      .should("have.text", "This should render")
+  })
+})

test/e2e-cypress/static/documents/features/try-it-out-non-200-response-body.yaml

@@ -0,0 +1,12 @@
+openapi: 3.0.0
+info:
+  version: 1.0.0
+  title: Test API
+  description: Test API
+paths:
+  /400-any:
+    get:
+      description: returns 400
+      responses:
+        default:
+          description: ok