fix(response-body): show download button both for non-empty Blob and string responses (#9343)

Co-authored-by: Vladimír Gorej <vladimir.gorej@gmail.com>

Refs #9298

test/unit/components/response-body.jsx

@@ -28,7 +28,6 @@ describe("<ResponseBody />", function () {
   it("renders ResponseBody as 'image/svg'", function () {
     props.contentType = "image/svg"
     const wrapper = shallow(<ResponseBody {...props} />)
-    console.warn(wrapper.debug())
     expect(wrapper.find("highlightCodeComponent").length).toEqual(0)
   })
 
@@ -36,17 +35,26 @@ describe("<ResponseBody />", function () {
     props.contentType = "text/plain"
     props.content = "test text"
     const wrapper = shallow(<ResponseBody {...props} />)
-    console.warn(wrapper.debug())
     expect(wrapper.find("highlightCodeComponent[canCopy]").length).toEqual(1)
   })
 
-  it("should render Download file link for non-empty response", function () {
+  it("should render Download file link for non-empty Blob response", function () {
     props.contentType = "application/octet-stream"
     props.content = new Blob(["\"test\""], { type: props.contentType })
     const wrapper = shallow(<ResponseBody {...props} />)
     expect(wrapper.text()).toMatch(/Download file/)
   })
 
+  it("should render Download file link for non-empty text response", function () {
+    props.contentType = "text/plain"
+    props.content = "test text"
+    props.headers = {
+      "Content-Disposition": "attachment; filename=\"test.txt\"",
+    }
+    const wrapper = shallow(<ResponseBody {...props} />)
+    expect(wrapper.text()).toMatch(/Download file/)
+  })
+
   it("should not render Download file link for empty response", function () {
     props.contentType = "application/octet-stream"
     props.content = new Blob()