refactor: BalancedBrackets (#5391)

Author: alxkm

src/main/java/com/thealgorithms/stacks/BalancedBrackets.java

@@ -59,26 +59,22 @@ public static boolean isBalanced(String brackets) {
             switch (bracket) {
             case '(':
             case '[':
+            case '<':
             case '{':
                 bracketsStack.push(bracket);
                 break;
             case ')':
             case ']':
+            case '>':
             case '}':
                 if (bracketsStack.isEmpty() || !isPaired(bracketsStack.pop(), bracket)) {
                     return false;
                 }
                 break;
             default:
-                /* other character is invalid */
                 return false;
             }
         }
         return bracketsStack.isEmpty();
     }
-
-    public static void main(String[] args) {
-        assert isBalanced("[()]{}{[()()]()}");
-        assert !isBalanced("[(])");
-    }
 }

src/test/java/com/thealgorithms/stacks/BalancedBracketsTest.java

@@ -0,0 +1,36 @@
+package com.thealgorithms.stacks;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+
+class BalancedBracketsTest {
+
+    @ParameterizedTest
+    @CsvSource({"(, )", "[, ]", "{, }", "<, >"})
+    void testIsPairedTrue(char opening, char closing) {
+        assertTrue(BalancedBrackets.isPaired(opening, closing));
+    }
+
+    @ParameterizedTest
+    @CsvSource({"(, ]", "[, )", "{, >", "<, )", "a, b", "!, @"})
+    void testIsPairedFalse(char opening, char closing) {
+        assertFalse(BalancedBrackets.isPaired(opening, closing));
+    }
+
+    @ParameterizedTest
+    @CsvSource({"'[()]{}{[()()]()}', true", "'()', true", "'[]', true", "'{}', true", "'<>', true", "'[{<>}]', true", "'', true", "'[(])', false", "'([)]', false", "'{[<]>}', false", "'[', false", "')', false", "'[{', false", "']', false", "'[a+b]', false", "'a+b', false"})
+    void testIsBalanced(String input, boolean expected) {
+        assertEquals(expected, BalancedBrackets.isBalanced(input));
+    }
+
+    @Test
+    void testIsBalancedNull() {
+        assertThrows(IllegalArgumentException.class, () -> BalancedBrackets.isBalanced(null));
+    }
+}