Add test case for RomanToInteger (#3686)

src/test/java/com/thealgorithms/conversions/RomanToIntegerTest.java

@@ -0,0 +1,14 @@
+package com.thealgorithms.conversions;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class RomanToIntegerTest {
+
+    @Test
+    public void testRomanToInteger() {
+        assertEquals(1994, RomanToInteger.romanToInt("MCMXCIV"));
+        assertEquals(58, RomanToInteger.romanToInt("LVIII"));
+    }
+}