test: cover negative SumOfSquares input

Author: oozan

src/test/java/com/thealgorithms/maths/SumOfSquaresTest.java

@@ -1,6 +1,7 @@
 package com.thealgorithms.maths;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import org.junit.jupiter.api.Test;
 
@@ -63,6 +64,11 @@ void testLargerNumbers() {
     @Test
     void testEdgeCases() {
         // Test edge case
-        assertEquals(1, SumOfSquares.minSquares(0)); // 0^2
+    
+    @Test
+    void testNegativeInput() {
+        assertThrows(IllegalArgumentException.class, () -> SumOfSquares.minSquares(-1));
+    }
+    assertEquals(1, SumOfSquares.minSquares(0)); // 0^2
     }
 }