fix test, omitempty for response_format ptr

chat.go

@@ -104,7 +104,7 @@ type ChatCompletionRequest struct {
 	Stream           bool                          `json:"stream,omitempty"`
 	Stop             []string                      `json:"stop,omitempty"`
 	PresencePenalty  float32                       `json:"presence_penalty,omitempty"`
-	ResponseFormat   *ChatCompletionResponseFormat `json:"response_format"`
+	ResponseFormat   *ChatCompletionResponseFormat `json:"response_format,omitempty"`
 	Seed             *int                          `json:"seed,omitempty"`
 	FrequencyPenalty float32                       `json:"frequency_penalty,omitempty"`
 	// LogitBias is must be a token id string (specified by their token ID in the tokenizer), not a word string.

chat_test.go

@@ -58,9 +58,8 @@ func TestChatRequestOmitEmpty(t *testing.T) {
 	})
 	checks.NoError(t, err)
 
-	// response_format is also set b/c it's a non-pointer struct
-	// and messages is also required
-	const expected = `{"model":"gpt-4","messages":null,"response_format":{}}`
+	// messages is also required so isn't omitted
+	const expected = `{"model":"gpt-4","messages":null}`
 	if string(data) != expected {
 		t.Errorf("expected JSON with all empty fields to be %v but was %v", expected, string(data))
 	}