Add test && docs

xirr_test.go

@@ -0,0 +1,72 @@
+package goxirr
+
+import (
+	"fmt"
+	"testing"
+	"time"
+)
+
+func ExampleXirr() {
+	firstDate := time.Date(2019, time.January, 1, 0, 0, 0, 0, time.UTC)
+	t1 := Transaction{
+		Date: firstDate,
+		Cash: -100,
+	}
+	t2 := Transaction{
+		Date: firstDate.Add(time.Hour * 24 * 365),
+		Cash: 112,
+	}
+
+	tas := Transactions{t1, t2}
+	fmt.Println(Xirr(tas))
+	// Output: 12
+}
+
+func TestXirr(t *testing.T) {
+	type args struct {
+		transactions []Transaction
+	}
+
+	var case1, case2, case3 args
+	case1.transactions = append(case1.transactions, Transaction{
+		Date: time.Date(2019, time.January, 1, 0, 0, 0, 0, time.UTC),
+		Cash: -100,
+	}, Transaction{
+		Date: time.Date(2020, time.January, 1, 0, 0, 0, 0, time.UTC),
+		Cash: 200,
+	})
+
+	case2.transactions = append(case2.transactions, Transaction{
+		Date: time.Date(2019, time.January, 1, 0, 0, 0, 0, time.UTC),
+		Cash: -100,
+	}, Transaction{
+		Date: time.Date(2020, time.January, 1, 0, 0, 0, 0, time.UTC),
+		Cash: 100,
+	})
+
+	case3.transactions = append(case3.transactions, Transaction{
+		Date: time.Date(2019, time.January, 1, 0, 0, 0, 0, time.UTC),
+		Cash: -100,
+	}, Transaction{
+		Date: time.Date(2020, time.January, 1, 0, 0, 0, 0, time.UTC),
+		Cash: 112,
+	})
+
+	tests := []struct {
+		name string
+		args args
+		want float64
+	}{
+		{name: "100%", args: case1, want: 100},
+		{name: "0%", args: case2, want: 0.0},
+		{name: "12%", args: case3, want: 12},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := Xirr(tt.args.transactions); got != tt.want {
+				t.Errorf("Xirr() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}