Add LongestValidParenthesesTest (#3612)

src/main/java/com/thealgorithms/dynamicprogramming/LongestValidParentheses.java

@@ -43,19 +43,4 @@ public class LongestValidParentheses {
 
         return max;
     }
-
-    public static void main(String[] args) {
-        Scanner sc = new Scanner(System.in);
-
-        while (true) {
-            String str = sc.nextLine();
-            if ("quit".equals(str)) {
-                break;
-            }
-
-            System.out.println("Len is: " + getLongestValidParentheses(str));
-        }
-
-        sc.close();
-    }
 }

src/test/java/com/thealgorithms/dynamicprogramming/LongestValidParenthesesTest

@@ -0,0 +1,51 @@
+package com.thealgorithms.dynamicprogramming;
+
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
+
+class LongestValidParenthesesTest {
+
+    LongestValidParentheses longestValidParentheses = new LongestValidParentheses();
+
+    @Test
+    void shouldReturnZeroWhenSingleOpeningParenthesisIsGiven() {
+        String input = "(";
+        int validLength = longestValidParentheses.getLongestValidParentheses(input);
+        assertEquals(0, validLength);
+    }
+
+    @Test
+    void shouldReturnZeroWhenSingleClosingParenthesisIsGiven() {
+        String input = ")";
+        int validLength = longestValidParentheses.getLongestValidParentheses(input);
+        assertEquals(0, validLength);
+    }
+
+    @Test
+    void shouldReturnZeroWhenNullStringIsGiven() {
+        String input = "";
+        int validLength = longestValidParentheses.getLongestValidParentheses(input);
+        assertEquals(0, validLength);
+    }
+
+    @Test
+    void shouldReturnTwoWhenTwoBalancedParenthesesAreGiven() {
+        String input = "()";
+        int validLength = longestValidParentheses.getLongestValidParentheses(input);
+        assertEquals(2, validLength);
+    }
+
+    @Test
+    void shouldReturnLengthWhenInputStringIsValid() {
+        String input = "()((()))";
+        int validLength = longestValidParentheses.getLongestValidParentheses(input);
+        assertEquals(8, validLength);
+    }
+
+    @Test
+    void shouldReturnValidLengthWhenInputStringIsGiven() {
+        String input = "((()((())))";
+        int validLength = longestValidParentheses.getLongestValidParentheses(input);
+        assertEquals(10, validLength);
+    }
+}