refactor(client): wrap all external requests in retry transport

backend/internal/zarinhub/token_manager_test.go

@@ -3,6 +3,7 @@ package zarinhub
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"net/http"
 	"net/http/httptest"
 	"sync"
@@ -220,3 +221,120 @@ func writeTokenResponse(
 		t.Fatalf("encode response: %v", err)
 	}
 }
+
+func TestTokenManagerRetriesOnTransientErrorsUntilSuccess(t *testing.T) {
+	var calls int
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		calls++
+		if calls == 1 {
+			w.WriteHeader(http.StatusServiceUnavailable)
+			return
+		}
+		writeTokenResponse(t, w, "retried-access", "retried-refresh", 28800)
+	}))
+	defer server.Close()
+
+	var recordedDelays []time.Duration
+	transport := NewRetryTransport(
+		server.Client().Transport,
+		time.Second,
+		2,
+	)
+	transport.retryWait = func(ctx context.Context, delay time.Duration) bool {
+		recordedDelays = append(recordedDelays, delay)
+		return true
+	}
+	httpClient := &http.Client{Transport: transport}
+
+	manager := NewTokenManager(httpClient, server.URL, "test-user", "test-pass")
+	token, err := manager.AccessToken(context.Background())
+	if err != nil {
+		t.Fatalf("AccessToken() error = %v", err)
+	}
+	if token != "retried-access" {
+		t.Errorf("token = %q, want retried-access", token)
+	}
+	if calls != 2 {
+		t.Errorf("calls = %d, want 2", calls)
+	}
+	if len(recordedDelays) != 1 {
+		t.Fatalf("len(recordedDelays) = %d, want 1", len(recordedDelays))
+	}
+	if recordedDelays[0] != 200*time.Millisecond {
+		t.Errorf("delay[0] = %v, want 200ms", recordedDelays[0])
+	}
+}
+
+func TestTokenManagerRetriesOnTimeoutUntilSuccess(t *testing.T) {
+	var calls int
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		calls++
+		if calls == 1 {
+			time.Sleep(150 * time.Millisecond)
+			w.WriteHeader(http.StatusOK)
+			return
+		}
+		writeTokenResponse(t, w, "timeout-recovered-access", "timeout-recovered-refresh", 28800)
+	}))
+	defer server.Close()
+
+	var recordedDelays []time.Duration
+	transport := NewRetryTransport(
+		server.Client().Transport,
+		50*time.Millisecond,
+		2,
+	)
+	transport.retryWait = func(ctx context.Context, delay time.Duration) bool {
+		recordedDelays = append(recordedDelays, delay)
+		return true
+	}
+	httpClient := &http.Client{Transport: transport}
+
+	manager := NewTokenManager(httpClient, server.URL, "test-user", "test-pass")
+	token, err := manager.AccessToken(context.Background())
+	if err != nil {
+		t.Fatalf("AccessToken() error = %v", err)
+	}
+	if token != "timeout-recovered-access" {
+		t.Errorf("token = %q, want timeout-recovered-access", token)
+	}
+	if calls != 2 {
+		t.Errorf("calls = %d, want 2", calls)
+	}
+	if len(recordedDelays) != 1 {
+		t.Fatalf("len(recordedDelays) = %d, want 1", len(recordedDelays))
+	}
+}
+
+func TestTokenManagerRetriesExhausted(t *testing.T) {
+	var calls int
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		calls++
+		w.WriteHeader(http.StatusBadGateway)
+	}))
+	defer server.Close()
+
+	var recordedDelays []time.Duration
+	transport := NewRetryTransport(
+		server.Client().Transport,
+		time.Second,
+		2,
+	)
+	transport.retryWait = func(ctx context.Context, delay time.Duration) bool {
+		recordedDelays = append(recordedDelays, delay)
+		return true
+	}
+	httpClient := &http.Client{Transport: transport}
+
+	manager := NewTokenManager(httpClient, server.URL, "test-user", "test-pass")
+	_, err := manager.AccessToken(context.Background())
+	if !errors.Is(err, ErrUnavailable) {
+		t.Fatalf("error = %v, want ErrUnavailable", err)
+	}
+	if calls != 3 {
+		t.Errorf("calls = %d, want 3", calls)
+	}
+	if len(recordedDelays) != 2 {
+		t.Fatalf("len(recordedDelays) = %d, want 2", len(recordedDelays))
+	}
+}