refactor: BalancedBrackets

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 +1,53 @@
+package com.thealgorithms.stacks;
+
+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;
+
+class BalancedBracketsTest {
+
+    @Test
+    void testIsPaired() {
+        assertTrue(BalancedBrackets.isPaired('(', ')'));
+        assertTrue(BalancedBrackets.isPaired('[', ']'));
+        assertTrue(BalancedBrackets.isPaired('{', '}'));
+        assertTrue(BalancedBrackets.isPaired('<', '>'));
+
+        assertFalse(BalancedBrackets.isPaired('(', ']'));
+        assertFalse(BalancedBrackets.isPaired('[', ')'));
+        assertFalse(BalancedBrackets.isPaired('{', '>'));
+        assertFalse(BalancedBrackets.isPaired('<', ')'));
+
+        assertFalse(BalancedBrackets.isPaired('a', 'b'));
+        assertFalse(BalancedBrackets.isPaired('!', '@'));
+    }
+
+    @Test
+    void testIsBalanced() {
+        assertTrue(BalancedBrackets.isBalanced("[()]{}{[()()]()}"));
+        assertTrue(BalancedBrackets.isBalanced("()"));
+        assertTrue(BalancedBrackets.isBalanced("[]"));
+        assertTrue(BalancedBrackets.isBalanced("{}"));
+        assertTrue(BalancedBrackets.isBalanced("<>"));
+        assertTrue(BalancedBrackets.isBalanced("[{<>}]"));
+        assertTrue(BalancedBrackets.isBalanced(""));
+
+        assertFalse(BalancedBrackets.isBalanced("[(])"));
+        assertFalse(BalancedBrackets.isBalanced("([)]"));
+        assertFalse(BalancedBrackets.isBalanced("{[<]>}"));
+        assertFalse(BalancedBrackets.isBalanced("["));
+        assertFalse(BalancedBrackets.isBalanced(")"));
+        assertFalse(BalancedBrackets.isBalanced("[{"));
+        assertFalse(BalancedBrackets.isBalanced("]"));
+
+        assertFalse(BalancedBrackets.isBalanced("[a+b]"));
+        assertFalse(BalancedBrackets.isBalanced("a+b"));
+    }
+
+    @Test
+    void testIsBalancedNull() {
+        assertThrows(IllegalArgumentException.class, () -> BalancedBrackets.isBalanced(null));
+    }
+}