feat: add unit tests for routing strategies and implement dynamic selector updates

Added comprehensive tests for `FillFirstSelector` and `RoundRobinSelector` to ensure proper behavior, including deterministic, cyclical, and concurrent scenarios. Introduced dynamic routing strategy updates in `service.go`, normalizing strategies and seamlessly switching between `fill-first` and `round-robin`. Updated `Manager` to support selector changes via the new `SetSelector` method.

sdk/cliproxy/auth/selector_test.go

@@ -0,0 +1,113 @@
+package auth
+
+import (
+	"context"
+	"errors"
+	"sync"
+	"testing"
+
+	cliproxyexecutor "github.com/router-for-me/CLIProxyAPI/v6/sdk/cliproxy/executor"
+)
+
+func TestFillFirstSelectorPick_Deterministic(t *testing.T) {
+	t.Parallel()
+
+	selector := &FillFirstSelector{}
+	auths := []*Auth{
+		{ID: "b"},
+		{ID: "a"},
+		{ID: "c"},
+	}
+
+	got, err := selector.Pick(context.Background(), "gemini", "", cliproxyexecutor.Options{}, auths)
+	if err != nil {
+		t.Fatalf("Pick() error = %v", err)
+	}
+	if got == nil {
+		t.Fatalf("Pick() auth = nil")
+	}
+	if got.ID != "a" {
+		t.Fatalf("Pick() auth.ID = %q, want %q", got.ID, "a")
+	}
+}
+
+func TestRoundRobinSelectorPick_CyclesDeterministic(t *testing.T) {
+	t.Parallel()
+
+	selector := &RoundRobinSelector{}
+	auths := []*Auth{
+		{ID: "b"},
+		{ID: "a"},
+		{ID: "c"},
+	}
+
+	want := []string{"a", "b", "c", "a", "b"}
+	for i, id := range want {
+		got, err := selector.Pick(context.Background(), "gemini", "", cliproxyexecutor.Options{}, auths)
+		if err != nil {
+			t.Fatalf("Pick() #%d error = %v", i, err)
+		}
+		if got == nil {
+			t.Fatalf("Pick() #%d auth = nil", i)
+		}
+		if got.ID != id {
+			t.Fatalf("Pick() #%d auth.ID = %q, want %q", i, got.ID, id)
+		}
+	}
+}
+
+func TestRoundRobinSelectorPick_Concurrent(t *testing.T) {
+	selector := &RoundRobinSelector{}
+	auths := []*Auth{
+		{ID: "b"},
+		{ID: "a"},
+		{ID: "c"},
+	}
+
+	start := make(chan struct{})
+	var wg sync.WaitGroup
+	errCh := make(chan error, 1)
+
+	goroutines := 32
+	iterations := 100
+	for i := 0; i < goroutines; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			<-start
+			for j := 0; j < iterations; j++ {
+				got, err := selector.Pick(context.Background(), "gemini", "", cliproxyexecutor.Options{}, auths)
+				if err != nil {
+					select {
+					case errCh <- err:
+					default:
+					}
+					return
+				}
+				if got == nil {
+					select {
+					case errCh <- errors.New("Pick() returned nil auth"):
+					default:
+					}
+					return
+				}
+				if got.ID == "" {
+					select {
+					case errCh <- errors.New("Pick() returned auth with empty ID"):
+					default:
+					}
+					return
+				}
+			}
+		}()
+	}
+
+	close(start)
+	wg.Wait()
+
+	select {
+	case err := <-errCh:
+		t.Fatalf("concurrent Pick() error = %v", err)
+	default:
+	}
+}