Return data as is if can't get json decoded

lib/ex_openai/client.ex

@@ -5,12 +5,11 @@ defmodule ExOpenAI.Client do
 
   def process_url(url), do: Config.api_url() <> url
 
-	def process_response_body(body) do
-    # audio/speech endpoint returns binary data, so leave as is
-    if is_binary(body) do
-      {:ok, body}
-    else
-      Jason.decode(body)
+  def process_response_body(body) do
+    case Jason.decode(body) do
+      {:ok, decoded_json} -> {:ok, decoded_json}
+      # audio/speech endpoint returns binary data, so leave as is
+      _ -> {:ok, body}
     end
   end
 

test/audio_tts_test.exs

@@ -0,0 +1,19 @@
+defmodule ExOpenAI.TextToSpeechTest do
+  use ExUnit.Case, async: true
+  use ExVCR.Mock, adapter: ExVCR.Adapter.Hackney
+
+  setup do
+    ExVCR.Config.cassette_library_dir("./test/fixture/vcr_cassettes")
+    :ok
+  end
+
+  test "audio text-to-speech" do
+    use_cassette "audio_text_to_speech" do
+      {:ok, res} =
+        ExOpenAI.Audio.create_speech("Hello, hello, hello, just a test.", :"tts-1-hd", :shimmer)
+
+      assert res != nil
+      assert byte_size(res) == 37920
+    end
+  end
+end