[shared] allow setting a user agent for the rest client (#5037)

shared/management/client/rest/client_test.go

@@ -4,10 +4,14 @@
 package rest_test
 
 import (
+	"context"
 	"net/http"
 	"net/http/httptest"
 	"testing"
 
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
 	"github.com/netbirdio/netbird/management/server/http/testing/testing_tools/channel"
 	"github.com/netbirdio/netbird/shared/management/client/rest"
 )
@@ -32,3 +36,50 @@ func withBlackBoxServer(t *testing.T, callback func(*rest.Client)) {
 	c := rest.New(server.URL, "nbp_apTmlmUXHSC4PKmHwtIZNaGr8eqcVI2gMURp")
 	callback(c)
 }
+
+func TestClient_UserAgent_Set(t *testing.T) {
+	expectedUserAgent := "TestApp/1.2.3"
+	mux := &http.ServeMux{}
+	server := httptest.NewServer(mux)
+	defer server.Close()
+
+	mux.HandleFunc("/api/accounts", func(w http.ResponseWriter, r *http.Request) {
+		assert.Equal(t, expectedUserAgent, r.Header.Get("User-Agent"))
+		w.WriteHeader(200)
+		_, err := w.Write([]byte("[]"))
+		require.NoError(t, err)
+	})
+
+	c := rest.NewWithOptions(
+		rest.WithManagementURL(server.URL),
+		rest.WithPAT("test-token"),
+		rest.WithUserAgent(expectedUserAgent),
+	)
+
+	_, err := c.Accounts.List(context.Background())
+	require.NoError(t, err)
+}
+
+func TestClient_UserAgent_NotSet(t *testing.T) {
+	mux := &http.ServeMux{}
+	server := httptest.NewServer(mux)
+	defer server.Close()
+
+	mux.HandleFunc("/api/accounts", func(w http.ResponseWriter, r *http.Request) {
+		// When no custom user agent is set, Go's default HTTP client will set one
+		// We just verify that the header exists (it will be Go's default)
+		userAgent := r.Header.Get("User-Agent")
+		assert.NotEmpty(t, userAgent)
+		w.WriteHeader(200)
+		_, err := w.Write([]byte("[]"))
+		require.NoError(t, err)
+	})
+
+	c := rest.NewWithOptions(
+		rest.WithManagementURL(server.URL),
+		rest.WithPAT("test-token"),
+	)
+
+	_, err := c.Accounts.List(context.Background())
+	require.NoError(t, err)
+}