add-factorial-test

pom.xml

@@ -13,5 +13,13 @@
         <maven.compiler.target>21</maven.compiler.target>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     </properties>
+    <dependencies>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <version>5.8.1</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
 
 </project>
\ No newline at end of file

src/main/java/cz/cvut/fel/ts1/homework1/Factorial.java

+package cz.cvut.fel.ts1.homework1;
+
+public class Factorial {
+    public static long factorial(int n) {
+        if (n < 0) {
+            throw new IllegalArgumentException("Factorial is not defined for negative numbers.");
+        }
+        long result = 1;
+        for (int i = 1; i <= n; i++) {
+            result *= i;
+        }
+        return result;
+    }
+}

src/test/java/cz/cvut/fel/ts1/homework1/TestFactorial.java

+package cz.cvut.fel.ts1.homework1;
+
+import org.junit.jupiter.api.Test;
+public class TestFactorial {
+    @Test
+    public void testFactorial() {
+        assert Factorial.factorial(0) == 1;
+        assert Factorial.factorial(1) == 1;
+        assert Factorial.factorial(2) == 2;
+        assert Factorial.factorial(3) == 6;
+        assert Factorial.factorial(4) == 24;
+    }
+    @Test
+    public void testFactorialNegative() {
+        try {
+            assert Factorial.factorial(-1) == 1;
+        } catch (IllegalArgumentException e) {
+            assert true;
+        }
+    }
+
+}