Fix issue #246

calendar/lunar/lunar.go

@@ -509,7 +509,7 @@ func (l Lunar) IsPigYear() bool {
 }
 
 func (g Gregorian) diffInDays(t time.Time) int {
-	return int(g.Time.Sub(t).Hours() / 24)
+	return int(g.Time.Truncate(time.Hour).Sub(t).Hours() / 24)
 }
 
 func (l Lunar) getOffsetInYear() int {

calendar/lunar/lunar_test.go

@@ -1772,3 +1772,46 @@ func TestLunar_IsPigYear(t *testing.T) {
 		})
 	}
 }
+
+// https://github.com/golang-module/carbon/issues/246
+func TestCarbon_Issue246(t *testing.T) {
+	type args struct {
+		g Gregorian
+	}
+	tests := []struct {
+		name string
+		args args
+		want string
+	}{
+		{
+			name: "case1",
+			args: args{FromGregorian(time.Date(2024, 9, 21, 0, 0, 0, 0, time.Local))},
+			want: "2024-08-19 00:00:00",
+		},
+		{
+			name: "case2",
+			args: args{FromGregorian(time.Date(2024, 9, 21, 23, 50, 0, 0, time.Local))},
+			want: "2024-08-19 23:50:00",
+		},
+		{
+			name: "case3",
+			args: args{FromGregorian(time.Date(2024, 9, 21, 23, 54, 0, 0, time.Local))},
+			want: "2024-08-19 23:54:00",
+		},
+		{
+			name: "case4",
+			args: args{FromGregorian(time.Date(2024, 9, 21, 23, 55, 0, 0, time.Local))},
+			want: "2024-08-19 23:55:00",
+		},
+		{
+			name: "case5",
+			args: args{FromGregorian(time.Date(2024, 9, 21, 23, 59, 0, 0, time.Local))},
+			want: "2024-08-19 23:59:00",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equalf(t, tt.want, (tt.args.g).ToLunar().String(), "args{%v}", tt.args.g)
+		})
+	}
+}