sub2api/backend/internal/service/openai_compat_prompt_cache_key_test.go

package service

import (
	"encoding/json"
	"testing"

	"github.com/Wei-Shaw/sub2api/internal/pkg/apicompat"
	"github.com/stretchr/testify/require"
)

func mustRawJSON(t *testing.T, s string) json.RawMessage {
	t.Helper()
	return json.RawMessage(s)
}

func TestShouldAutoInjectPromptCacheKeyForCompat(t *testing.T) {
	require.True(t, shouldAutoInjectPromptCacheKeyForCompat("gpt-5.4"))
	require.True(t, shouldAutoInjectPromptCacheKeyForCompat("gpt-5.3"))
	require.True(t, shouldAutoInjectPromptCacheKeyForCompat("gpt-5.3-codex"))
	require.False(t, shouldAutoInjectPromptCacheKeyForCompat("gpt-4o"))
}

func TestDeriveCompatPromptCacheKey_StableAcrossLaterTurns(t *testing.T) {
	base := &apicompat.ChatCompletionsRequest{
		Model: "gpt-5.4",
		Messages: []apicompat.ChatMessage{
			{Role: "system", Content: mustRawJSON(t, `"You are helpful."`)},
			{Role: "user", Content: mustRawJSON(t, `"Hello"`)},
		},
	}
	extended := &apicompat.ChatCompletionsRequest{
		Model: "gpt-5.4",
		Messages: []apicompat.ChatMessage{
			{Role: "system", Content: mustRawJSON(t, `"You are helpful."`)},
			{Role: "user", Content: mustRawJSON(t, `"Hello"`)},
			{Role: "assistant", Content: mustRawJSON(t, `"Hi there!"`)},
			{Role: "user", Content: mustRawJSON(t, `"How are you?"`)},
		},
	}

	k1 := deriveCompatPromptCacheKey(base, "gpt-5.4")
	k2 := deriveCompatPromptCacheKey(extended, "gpt-5.4")
	require.Equal(t, k1, k2, "cache key should be stable across later turns")
	require.NotEmpty(t, k1)
}

func TestDeriveCompatPromptCacheKey_DiffersAcrossSessions(t *testing.T) {
	req1 := &apicompat.ChatCompletionsRequest{
		Model: "gpt-5.4",
		Messages: []apicompat.ChatMessage{
			{Role: "user", Content: mustRawJSON(t, `"Question A"`)},
		},
	}
	req2 := &apicompat.ChatCompletionsRequest{
		Model: "gpt-5.4",
		Messages: []apicompat.ChatMessage{
			{Role: "user", Content: mustRawJSON(t, `"Question B"`)},
		},
	}

	k1 := deriveCompatPromptCacheKey(req1, "gpt-5.4")
	k2 := deriveCompatPromptCacheKey(req2, "gpt-5.4")
	require.NotEqual(t, k1, k2, "different first user messages should yield different keys")
}