1package anthropic
 2
 3import (
 4	"encoding/json"
 5	"net/http"
 6	"net/http/httptest"
 7	"testing"
 8
 9	"charm.land/fantasy"
10	"github.com/stretchr/testify/assert"
11	"github.com/stretchr/testify/require"
12)
13
14func TestUserAgent(t *testing.T) {
15	t.Parallel()
16
17	newUAServer := func() (*httptest.Server, *[]map[string]string) {
18		var captured []map[string]string
19		server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
20			h := make(map[string]string)
21			for k, v := range r.Header {
22				if len(v) > 0 {
23					h[k] = v[0]
24				}
25			}
26			captured = append(captured, h)
27
28			w.Header().Set("Content-Type", "application/json")
29			_ = json.NewEncoder(w).Encode(mockAnthropicGenerateResponse())
30		}))
31		return server, &captured
32	}
33
34	prompt := fantasy.Prompt{
35		{
36			Role:    fantasy.MessageRoleUser,
37			Content: []fantasy.MessagePart{fantasy.TextPart{Text: "Hi"}},
38		},
39	}
40
41	t.Run("default UA applied", func(t *testing.T) {
42		t.Parallel()
43		server, captured := newUAServer()
44		defer server.Close()
45
46		p, err := New(WithAPIKey("k"), WithBaseURL(server.URL))
47		require.NoError(t, err)
48		model, _ := p.LanguageModel(t.Context(), "claude-sonnet-4-20250514")
49		_, _ = model.Generate(t.Context(), fantasy.Call{Prompt: prompt})
50
51		require.Len(t, *captured, 1)
52		assert.Equal(t, "Charm Fantasy/"+fantasy.Version, (*captured)[0]["User-Agent"])
53	})
54
55	t.Run("WithUserAgent wins over both", func(t *testing.T) {
56		t.Parallel()
57		server, captured := newUAServer()
58		defer server.Close()
59
60		p, err := New(
61			WithAPIKey("k"),
62			WithBaseURL(server.URL),
63			WithHeaders(map[string]string{"User-Agent": "from-headers"}),
64			WithUserAgent("explicit-ua"),
65		)
66		require.NoError(t, err)
67		model, _ := p.LanguageModel(t.Context(), "claude-sonnet-4-20250514")
68		_, _ = model.Generate(t.Context(), fantasy.Call{Prompt: prompt})
69
70		require.Len(t, *captured, 1)
71		assert.Equal(t, "explicit-ua", (*captured)[0]["User-Agent"])
72	})
73}