✨ (roman-numerals): add seventh-test and refator

Author: yuanyu90221

property-base-test/roman_number.go

@@ -8,6 +8,8 @@ type RomanNumerals struct {
 }
 
 var allRomanNumerals = []RomanNumerals{
+	{50, "L"},
+	{40, "XL"},
 	{10, "X"},
 	{9, "IX"},
 	{5, "V"},

property-base-test/roman_number_test.go

@@ -14,6 +14,11 @@ func TestRomanNumerals(t *testing.T) {
 		{"4 gets converted to IV", 4, "IV"},
 		{"5 gets converted to V", 5, "V"},
 		{"9 gets converted to IX", 9, "IX"},
+		{"10 gets converted to X", 10, "X"},
+		{"40 gets converted to XL", 40, "XL"},
+		{"47 gets converted to XLVII", 47, "XLVII"},
+		{"49 gets converted to XLIX", 49, "XLIX"},
+		{"50 gets converted to L", 50, "L"},
 	}
 
 	for _, test := range cases {