kucoin: Fix fetching fee rates for multiple pairs (#1370)

* kucoin: Fix fetching fee rates for multiple pairs

* Update exchanges/kucoin/kucoin_test.go

Co-authored-by: Adrian Gallagher <adrian.gallagher@thrasher.io>

* NITS: WOW

* glorious: nits

---------

Co-authored-by: Ryan O'Hara-Reid <ryan.oharareid@thrasher.io>
Co-authored-by: Adrian Gallagher <adrian.gallagher@thrasher.io>

exchanges/kucoin/kucoin.go

@@ -1647,13 +1647,14 @@ func (ku *Kucoin) GetBasicFee(ctx context.Context, currencyType string) (*Fees,
 }
 
 // GetTradingFee get fee rate of trading pairs
-func (ku *Kucoin) GetTradingFee(ctx context.Context, symbols string) ([]Fees, error) {
-	params := url.Values{}
-	if symbols != "" {
-		params.Set("symbols", symbols)
+// WARNING: There is a limit of 10 currency pairs allowed to be requested per call.
+func (ku *Kucoin) GetTradingFee(ctx context.Context, pairs currency.Pairs) ([]Fees, error) {
+	if len(pairs) == 0 {
+		return nil, currency.ErrCurrencyPairsEmpty
 	}
+	path := kucoinTradingFee + "?symbols=" + pairs.Upper().Join()
 	var resp []Fees
-	return resp, ku.SendAuthHTTPRequest(ctx, exchange.RestSpot, defaultSpotEPL, http.MethodGet, common.EncodeURLValues(kucoinTradingFee, params), nil, &resp)
+	return resp, ku.SendAuthHTTPRequest(ctx, exchange.RestSpot, defaultSpotEPL, http.MethodGet, path, nil, &resp)
 }
 
 // SendHTTPRequest sends an unauthenticated HTTP request

exchanges/kucoin/kucoin_test.go

@@ -1096,11 +1096,45 @@ func TestGetBasicFee(t *testing.T) {
 
 func TestGetTradingFee(t *testing.T) {
 	t.Parallel()
+
+	_, err := ku.GetTradingFee(context.Background(), nil)
+	if !errors.Is(err, currency.ErrCurrencyPairsEmpty) {
+		t.Fatalf("received %v, expected %v", err, currency.ErrCurrencyPairsEmpty)
+	}
+
 	sharedtestvalues.SkipTestIfCredentialsUnset(t, ku)
 
-	_, err := ku.GetTradingFee(context.Background(), "BTC-USDT")
+	avail, err := ku.GetAvailablePairs(asset.Spot)
 	if err != nil {
-		t.Error("GetTradingFee() error", err)
+		t.Fatal(err)
+	}
+
+	pairs := currency.Pairs{avail[0]}
+	btcusdTradingFee, err := ku.GetTradingFee(context.Background(), pairs)
+	if !errors.Is(err, nil) {
+		t.Fatalf("received %v, expected %v", err, nil)
+	}
+
+	if len(btcusdTradingFee) != 1 {
+		t.Error("GetTradingFee() error, expected 1 pair")
+	}
+
+	// NOTE: Test below will error out from an external call as this will exceed
+	// the allowed pairs. If this does not error then this endpoint will allow
+	// more items to be requested.
+	pairs = append(pairs, avail[1:11]...)
+	_, err = ku.GetTradingFee(context.Background(), pairs)
+	if errors.Is(err, nil) {
+		t.Fatalf("received %v, expected %v", err, "code: 200000 message: symbols size invalid.")
+	}
+
+	got, err := ku.GetTradingFee(context.Background(), pairs[:10])
+	if !errors.Is(err, nil) {
+		t.Fatalf("received %v, expected %v", err, nil)
+	}
+
+	if len(got) != 10 {
+		t.Error("GetTradingFee() error, expected 10 pairs")
 	}
 }
 

exchanges/kucoin/kucoin_types.go

@@ -56,11 +56,14 @@ func (e Error) GetError() error {
 		return err
 	}
 	switch code {
-	case 200000, 200:
+	case 200:
 		return nil
-	default:
-		return fmt.Errorf("code: %s message: %s", e.Code, e.Msg)
+	case 200000:
+		if e.Msg == "" {
+			return nil
+		}
 	}
+	return fmt.Errorf("code: %s message: %s", e.Code, e.Msg)
 }
 
 // SymbolInfo stores symbol information

exchanges/kucoin/kucoin_wrapper.go

@@ -1351,7 +1351,7 @@ func (ku *Kucoin) GetFeeByType(ctx context.Context, feeBuilder *exchange.FeeBuil
 	switch feeBuilder.FeeType {
 	case exchange.CryptocurrencyWithdrawalFee,
 		exchange.CryptocurrencyTradeFee:
-		fee, err := ku.GetTradingFee(ctx, feeBuilder.Pair.String())
+		fee, err := ku.GetTradingFee(ctx, currency.Pairs{feeBuilder.Pair})
 		if err != nil {
 			return 0, err
 		}