fix precision problem

pkg/strategy/dca2/open_position.go

@@ -89,6 +89,7 @@ func generateOpenPositionOrders(market types.Market, quoteInvestment, profit, pr
 		var quantity fixedpoint.Value
 		// all the profit will use in the first order
 		if i == 0 {
+			profit = market.TruncatePrice(profit)
 			quantity = market.TruncateQuantity(notional.Add(profit).Div(prices[i]))
 		} else {
 			quantity = market.TruncateQuantity(notional.Div(prices[i]))

pkg/strategy/dca2/open_position_test.go

@@ -67,12 +67,29 @@ func TestGenerateOpenPositionOrders(t *testing.T) {
 		assert.Equal(Number("0.102055"), submitOrders[3].Quantity)
 	})
 
-	t.Run("case 2: some orders' price will below 0, so we should not create such order", func(t *testing.T) {
+	t.Run("case 2: profit need to be truncated to avoid precision problem", func(t *testing.T) {
+		quoteInvestment := Number("1000")
+		profit := Number("99.47871711")
+		askPrice := Number("40409.72")
+		margin := Number("0.1")
+		submitOrders, err := generateOpenPositionOrders(strategy.Market, quoteInvestment, profit, askPrice, margin, 2, strategy.OrderGroupID)
+		if !assert.NoError(err) {
+			return
+		}
+
+		assert.Len(submitOrders, 2)
+		assert.Equal(Number("40409.72"), submitOrders[0].Price)
+		assert.Equal(Number("0.014834"), submitOrders[0].Quantity)
+		assert.Equal(Number("36368.74"), submitOrders[1].Price)
+		assert.Equal(Number("0.013748"), submitOrders[1].Quantity)
+	})
+
+	t.Run("case 3: some orders' price will below 0, so we should not create such order", func(t *testing.T) {
 	})
 
-	t.Run("case 3: notional is too small, so we should decrease num of orders", func(t *testing.T) {
+	t.Run("case 4: notional is too small, so we should decrease num of orders", func(t *testing.T) {
 	})
 
-	t.Run("case 4: quantity is too small, so we should decrease num of orders", func(t *testing.T) {
+	t.Run("case 5: quantity is too small, so we should decrease num of orders", func(t *testing.T) {
 	})
 }