// CSE 143, Winter 2011, Marty Stepp
// This JUnit test program checks the functionality of our pow method. 

import static org.junit.Assert.*;
import org.junit.*;

public class PowersTest {
    // Returns (base) raised to the (exponent)th power, recursively.
    // Precondition: exponent >= 0
    public static int pow(int base, int exponent) {
    	// System.out.println("pow " + base + " " + exponent);
    	if (exponent == 0 || base == 1) {
    		return 1;
    	} else if (exponent % 2 == 0) {
    		return pow(base * base, exponent / 2);
    	} else {
    		// exponent > 1
    		return base * pow(base, exponent - 1);
    	}
    }
	
	@Test
	public void test1() {
		// assertEquals(81, pow(3, 4));
		helper(3, 4, 81);
	}
	
	@Test
	public void test2() {
		helper(2, 8, 256);
	}
	
	@Test
	public void test3() {
		helper(10, 5, 100000);
	}
	
	@Test
	public void test4() {
		helper(-4, 5, -4*-4*-4*-4*-4);
	}
	
	@Test
	public void test5() {
		helper(2, 30, (int) Math.pow(2, 30));
	}
	
	private void helper(int b, int e, int expect) {
		assertEquals("pow(" + b + ", " + e + ")", expect, pow(b, e));
	}
}