some tweaks to cart

pkg/proxy/remotehost_test.go

@@ -0,0 +1,109 @@
+package proxy
+
+import (
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"sync/atomic"
+	"testing"
+)
+
+func TestRemoteHostSharesHTTPTransport(t *testing.T) {
+	h1, err := NewRemoteHost[struct{}]("10.0.0.1", "8080")
+	if err != nil {
+		t.Fatal(err)
+	}
+	h2, err := NewRemoteHost[struct{}]("10.0.0.2", "8080")
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() {
+		_ = h1.Close()
+		_ = h2.Close()
+	})
+
+	if h1.client.Transport != h2.client.Transport {
+		t.Fatal("expected all RemoteHost instances to share one http.Transport")
+	}
+}
+
+func TestRemoteHostProxyUsesKeepAlive(t *testing.T) {
+	var requests atomic.Int32
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		requests.Add(1)
+		w.WriteHeader(http.StatusOK)
+		_, _ = io.WriteString(w, `{"ok":true}`)
+	}))
+	t.Cleanup(srv.Close)
+
+	host, port, err := splitHostPort(srv.URL)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	remote, err := NewRemoteHost[struct{}](host, port)
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() { _ = remote.Close() })
+
+	for range 3 {
+		mw := NewMockResponseWriter()
+		req, err := http.NewRequest(http.MethodGet, "/cart/1", nil)
+		if err != nil {
+			t.Fatal(err)
+		}
+		ok, err := remote.Proxy(1, mw, req, nil)
+		if err != nil || !ok {
+			t.Fatalf("Proxy failed: ok=%v err=%v status=%d body=%q", ok, err, mw.StatusCode, mw.Body.String())
+		}
+	}
+
+	if requests.Load() != 3 {
+		t.Fatalf("server requests = %d, want 3", requests.Load())
+	}
+}
+
+func TestRemoteHostCloseDoesNotBreakSharedTransport(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		w.WriteHeader(http.StatusOK)
+	}))
+	t.Cleanup(srv.Close)
+
+	host, port, err := splitHostPort(srv.URL)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	h1, err := NewRemoteHost[struct{}](host, port)
+	if err != nil {
+		t.Fatal(err)
+	}
+	h2, err := NewRemoteHost[struct{}](host, port)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if err := h1.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	mw := NewMockResponseWriter()
+	req, err := http.NewRequest(http.MethodGet, "/health", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	ok, err := h2.Proxy(0, mw, req, nil)
+	if err != nil || !ok || mw.StatusCode != http.StatusOK {
+		t.Fatalf("second host proxy after first close failed: ok=%v err=%v status=%d", ok, err, mw.StatusCode)
+	}
+}
+
+func splitHostPort(rawURL string) (host, port string, err error) {
+	u, err := url.Parse(rawURL)
+	if err != nil {
+		return "", "", err
+	}
+	return u.Hostname(), u.Port(), nil
+}