first version

internal/money/rounding_test.go

@@ -0,0 +1,39 @@
+package money
+
+import (
+	"testing"
+
+	"github.com/shopspring/decimal"
+)
+
+func d(raw string) decimal.Decimal {
+	v, err := decimal.NewFromString(raw)
+	if err != nil {
+		panic(err)
+	}
+	return v
+}
+
+func TestRoundToTick(t *testing.T) {
+	tests := []struct {
+		price string
+		tick  string
+		mode  RoundMode
+		want  string
+	}{
+		{"10.12346", "0.0001", RoundNearest, "10.1235"},
+		{"10.126", "0.01", RoundFloor, "10.12"},
+		{"10.126", "0.01", RoundCeil, "10.13"},
+		{"10.24", "0.5", RoundNearest, "10"},
+		{"10.26", "0.5", RoundNearest, "10.5"},
+	}
+	for _, tt := range tests {
+		got, err := RoundToTick(d(tt.price), d(tt.tick), tt.mode)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if !got.Equal(d(tt.want)) {
+			t.Fatalf("RoundToTick(%s,%s)=%s want %s", tt.price, tt.tick, got, tt.want)
+		}
+	}
+}