diff --git a/calendar/gregorian_test.go b/calendar/gregorian_test.go
index e10680cc..af3c002d 100755
--- a/calendar/gregorian_test.go
+++ b/calendar/gregorian_test.go
@@ -1,7 +1,6 @@
 package calendar
 
 import (
-	"strconv"
 	"testing"
 	"time"
 
@@ -13,20 +12,23 @@ func TestGregorian_Year(t *testing.T) {
 		g Gregorian
 	}
 	tests := []struct {
+		name string
 		args args
 		want int
 	}{
 		{
+			name: "case1",
 			args: args{NewGregorian(time.Time{})},
 			want: 0,
 		},
 		{
+			name: "case2",
 			args: args{NewGregorian(time.Date(2020, 8, 5, 13, 14, 15, 0, time.Local))},
 			want: 2020,
 		},
 	}
-	for index, tt := range tests {
-		t.Run(strconv.Itoa(index), func(t *testing.T) {
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
 			assert.Equalf(t, tt.want, tt.args.g.Year(), "args(%v)", tt.args.g)
 		})
 	}
@@ -37,20 +39,23 @@ func TestGregorian_Month(t *testing.T) {
 		g Gregorian
 	}
 	tests := []struct {
+		name string
 		args args
 		want int
 	}{
 		{
+			name: "case1",
 			args: args{NewGregorian(time.Time{})},
 			want: 0,
 		},
 		{
+			name: "case2",
 			args: args{NewGregorian(time.Date(2020, 8, 5, 13, 14, 15, 0, time.Local))},
 			want: 8,
 		},
 	}
-	for index, tt := range tests {
-		t.Run(strconv.Itoa(index), func(t *testing.T) {
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
 			assert.Equalf(t, tt.want, tt.args.g.Month(), "args(%v)", tt.args.g)
 		})
 	}
@@ -61,20 +66,23 @@ func TestGregorian_Week(t *testing.T) {
 		g Gregorian
 	}
 	tests := []struct {
+		name string
 		args args
 		want int
 	}{
 		{
+			name: "case1",
 			args: args{NewGregorian(time.Time{})},
 			want: 0,
 		},
 		{
+			name: "case2",
 			args: args{NewGregorian(time.Date(2020, 8, 5, 13, 14, 15, 0, time.Local))},
 			want: 3,
 		},
 	}
-	for index, tt := range tests {
-		t.Run(strconv.Itoa(index), func(t *testing.T) {
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
 			assert.Equalf(t, tt.want, tt.args.g.Week(), "args(%v)", tt.args.g)
 		})
 	}
@@ -85,20 +93,23 @@ func TestGregorian_Day(t *testing.T) {
 		g Gregorian
 	}
 	tests := []struct {
+		name string
 		args args
 		want int
 	}{
 		{
+			name: "case1",
 			args: args{NewGregorian(time.Time{})},
 			want: 0,
 		},
 		{
+			name: "case2",
 			args: args{NewGregorian(time.Date(2020, 8, 5, 13, 14, 15, 0, time.Local))},
 			want: 5,
 		},
 	}
-	for index, tt := range tests {
-		t.Run(strconv.Itoa(index), func(t *testing.T) {
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
 			assert.Equalf(t, tt.want, tt.args.g.Day(), "args(%v)", tt.args.g)
 		})
 	}
@@ -109,20 +120,23 @@ func TestGregorian_Hour(t *testing.T) {
 		g Gregorian
 	}
 	tests := []struct {
+		name string
 		args args
 		want int
 	}{
 		{
+			name: "case1",
 			args: args{NewGregorian(time.Time{})},
 			want: 0,
 		},
 		{
+			name: "case2",
 			args: args{NewGregorian(time.Date(2020, 8, 5, 13, 14, 15, 0, time.Local))},
 			want: 13,
 		},
 	}
-	for index, tt := range tests {
-		t.Run(strconv.Itoa(index), func(t *testing.T) {
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
 			assert.Equalf(t, tt.want, tt.args.g.Hour(), "args(%v)", tt.args.g)
 		})
 	}
@@ -133,20 +147,23 @@ func TestGregorian_Minute(t *testing.T) {
 		g Gregorian
 	}
 	tests := []struct {
+		name string
 		args args
 		want int
 	}{
 		{
+			name: "case1",
 			args: args{NewGregorian(time.Time{})},
 			want: 0,
 		},
 		{
+			name: "case2",
 			args: args{NewGregorian(time.Date(2020, 8, 5, 13, 14, 15, 0, time.Local))},
 			want: 14,
 		},
 	}
-	for index, tt := range tests {
-		t.Run(strconv.Itoa(index), func(t *testing.T) {
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
 			assert.Equalf(t, tt.want, tt.args.g.Minute(), "args(%v)", tt.args.g)
 		})
 	}
@@ -157,20 +174,23 @@ func TestGregorian_Second(t *testing.T) {
 		g Gregorian
 	}
 	tests := []struct {
+		name string
 		args args
 		want int
 	}{
 		{
+			name: "case1",
 			args: args{NewGregorian(time.Time{})},
 			want: 0,
 		},
 		{
+			name: "case2",
 			args: args{NewGregorian(time.Date(2020, 8, 5, 13, 14, 15, 0, time.Local))},
 			want: 15,
 		},
 	}
-	for index, tt := range tests {
-		t.Run(strconv.Itoa(index), func(t *testing.T) {
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
 			assert.Equalf(t, tt.want, tt.args.g.Second(), "args(%v)", tt.args.g)
 		})
 	}
@@ -181,20 +201,23 @@ func TestGregorian_String(t *testing.T) {
 		g Gregorian
 	}
 	tests := []struct {
+		name string
 		args args
 		want string
 	}{
 		{
+			name: "case1",
 			args: args{NewGregorian(time.Time{})},
 			want: "",
 		},
 		{
+			name: "case2",
 			args: args{NewGregorian(time.Date(2020, 8, 5, 13, 14, 15, 0, time.Local))},
 			want: "2020-08-05 13:14:15",
 		},
 	}
-	for index, tt := range tests {
-		t.Run(strconv.Itoa(index), func(t *testing.T) {
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
 			assert.Equalf(t, tt.want, tt.args.g.String(), "args(%v)", tt.args.g)
 		})
 	}
@@ -205,20 +228,23 @@ func TestGregorian_Location(t *testing.T) {
 		g Gregorian
 	}
 	tests := []struct {
+		name string
 		args args
 		want string
 	}{
 		{
+			name: "case1",
 			args: args{NewGregorian(time.Time{})},
 			want: "UTC",
 		},
 		{
+			name: "case2",
 			args: args{NewGregorian(time.Date(2020, 8, 5, 13, 14, 15, 0, time.Local))},
 			want: "Local",
 		},
 	}
-	for index, tt := range tests {
-		t.Run(strconv.Itoa(index), func(t *testing.T) {
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
 			assert.Equalf(t, tt.want, tt.args.g.Location().String(), "args(%v)", tt.args.g)
 		})
 	}
@@ -229,26 +255,29 @@ func TestGregorian_Date(t *testing.T) {
 		Time time.Time
 	}
 	tests := []struct {
+		name      string
 		args      args
 		wantYear  int
 		wantMonth int
 		wantDay   int
 	}{
 		{
+			name:      "case1",
 			args:      args{time.Time{}},
 			wantYear:  0,
 			wantMonth: 0,
 			wantDay:   0,
 		},
 		{
+			name:      "case2",
 			args:      args{time.Date(2020, 8, 5, 13, 14, 15, 0, time.Local)},
 			wantYear:  2020,
 			wantMonth: 8,
 			wantDay:   5,
 		},
 	}
-	for index, tt := range tests {
-		t.Run(strconv.Itoa(index), func(t *testing.T) {
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
 			g := NewGregorian(tt.args.Time)
 			gotYear, gotMonth, gotDay := g.Date()
 			assert.Equalf(t, tt.wantYear, gotYear, "Date()")
@@ -263,26 +292,29 @@ func TestGregorian_Clock(t *testing.T) {
 		Time time.Time
 	}
 	tests := []struct {
+		name       string
 		args       args
 		wantHour   int
 		wantMinute int
 		wantSecond int
 	}{
 		{
+			name:       "case1",
 			args:       args{time.Time{}},
 			wantHour:   0,
 			wantMinute: 0,
 			wantSecond: 0,
 		},
 		{
+			name:       "case2",
 			args:       args{time.Date(2020, 8, 5, 13, 14, 15, 0, time.Local)},
 			wantHour:   13,
 			wantMinute: 14,
 			wantSecond: 15,
 		},
 	}
-	for index, tt := range tests {
-		t.Run(strconv.Itoa(index), func(t *testing.T) {
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
 			g := NewGregorian(tt.args.Time)
 			gotHour, goMinute, gotSecond := g.Clock()
 			assert.Equalf(t, tt.wantHour, gotHour, "Clock()")
@@ -297,20 +329,23 @@ func TestGregorian_IsZero(t *testing.T) {
 		g Gregorian
 	}
 	tests := []struct {
+		name string
 		args args
 		want bool
 	}{
 		{
+			name: "case1",
 			args: args{NewGregorian(time.Time{})},
 			want: true,
 		},
 		{
+			name: "case2",
 			args: args{NewGregorian(time.Date(2020, 8, 5, 13, 14, 15, 0, time.Local))},
 			want: false,
 		},
 	}
-	for index, tt := range tests {
-		t.Run(strconv.Itoa(index), func(t *testing.T) {
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
 			assert.Equalf(t, tt.want, tt.args.g.IsZero(), "args(%v)", tt.args.g)
 		})
 	}
@@ -321,24 +356,28 @@ func TestGregorian_IsLeapYear(t *testing.T) {
 		g Gregorian
 	}
 	tests := []struct {
+		name string
 		args args
 		want bool
 	}{
 		{
+			name: "case1",
 			args: args{NewGregorian(time.Time{})},
 			want: false,
 		},
 		{
+			name: "case2",
 			args: args{NewGregorian(time.Date(2020, 8, 5, 0, 0, 0, 0, time.Local))},
 			want: true,
 		},
 		{
+			name: "case3",
 			args: args{NewGregorian(time.Date(2021, 8, 5, 0, 0, 0, 0, time.Local))},
 			want: false,
 		},
 	}
-	for index, tt := range tests {
-		t.Run(strconv.Itoa(index), func(t *testing.T) {
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
 			assert.Equalf(t, tt.want, tt.args.g.IsLeapYear(), "args(%v)", tt.args.g)
 		})
 	}