Offline worst case trade fees (#274)

* Really basic getSimulated fee function everywhere

* Worst case fees for all exchanges

* Adds tests, fixes comment spacing. Adds wrapper logic. Makes test api key var name consistent. Removes some okcoin ETT tests

* Removes redundant functions

* linting issues. Fixes introduces huobi issues

* More linting

* Stops trying to hide ETT problems, uses iota

* Skips ETT tests for now

exchanges/bittrex/bittrex.go

@@ -530,6 +530,8 @@ func (b *Bittrex) GetFee(feeBuilder *exchange.FeeBuilder) (float64, error) {
 		fee = calculateTradingFee(feeBuilder.PurchasePrice, feeBuilder.Amount)
 	case exchange.CryptocurrencyWithdrawalFee:
 		fee, err = b.GetWithdrawalFee(feeBuilder.Pair.Base)
+	case exchange.OfflineTradeFee:
+		fee = calculateTradingFee(feeBuilder.PurchasePrice, feeBuilder.Amount)
 	}
 	if fee < 0 {
 		fee = 0
@@ -554,7 +556,7 @@ func (b *Bittrex) GetWithdrawalFee(c currency.Code) (float64, error) {
 }
 
 // calculateTradingFee returns the fee for trading any currency on Bittrex
-func calculateTradingFee(purchasePrice, amount float64) float64 {
-	var fee = 0.0025
-	return fee * purchasePrice * amount
+func calculateTradingFee(price, amount float64) float64 {
+	return 0.0025 * price * amount
+
 }

exchanges/bittrex/bittrex_test.go

@@ -228,6 +228,21 @@ func setFeeBuilder() *exchange.FeeBuilder {
 	}
 }
 
+// TestGetFeeByTypeOfflineTradeFee logic test
+func TestGetFeeByTypeOfflineTradeFee(t *testing.T) {
+	var feeBuilder = setFeeBuilder()
+	b.GetFeeByType(feeBuilder)
+	if apiKey == "" || apiSecret == "" {
+		if feeBuilder.FeeType != exchange.OfflineTradeFee {
+			t.Errorf("Expected %v, received %v", exchange.OfflineTradeFee, feeBuilder.FeeType)
+		}
+	} else {
+		if feeBuilder.FeeType != exchange.CryptocurrencyTradeFee {
+			t.Errorf("Expected %v, received %v", exchange.CryptocurrencyTradeFee, feeBuilder.FeeType)
+		}
+	}
+}
+
 func TestGetFee(t *testing.T) {
 	b.SetDefaults()
 	TestSetup(t)

exchanges/bittrex/bittrex_wrapper.go

@@ -300,6 +300,10 @@ func (b *Bittrex) GetWebsocket() (*exchange.Websocket, error) {
 
 // GetFeeByType returns an estimate of fee based on type of transaction
 func (b *Bittrex) GetFeeByType(feeBuilder *exchange.FeeBuilder) (float64, error) {
+	if (b.APIKey == "" || b.APISecret == "") && // Todo check connection status
+		feeBuilder.FeeType == exchange.CryptocurrencyTradeFee {
+		feeBuilder.FeeType = exchange.OfflineTradeFee
+	}
 	return b.GetFee(feeBuilder)
 
 }