Remove old test

The method that was tested here should have been removed back in https://github.com/h2database/h2database/commit/14664665e4285659b6a48536a490ab0787841470.
Instead it was moved next to its test and was unused ever since.

h2/src/test/org/h2/test/unit/TestMathUtils.java

@@ -5,9 +5,7 @@
  */
 package org.h2.test.unit;
 
-import java.math.BigInteger;
 import org.h2.test.TestBase;
-import org.h2.test.utils.AssertThrows;
 import org.h2.util.MathUtils;
 
 /**
@@ -27,7 +25,6 @@ public class TestMathUtils extends TestBase {
     @Override
     public void test() {
         testRandom();
-        testFactorial();
     }
 
     private void testRandom() {
@@ -51,42 +48,4 @@ public class TestMathUtils extends TestBase {
         assertTrue(data.length > 10);
     }
 
-    private void testFactorial() {
-        new AssertThrows(IllegalArgumentException.class) { @Override
-        public void test() {
-            factorial(-1);
-        }};
-        assertEquals("1", factorial(0).toString());
-        assertEquals("1", factorial(1).toString());
-        assertEquals("2", factorial(2).toString());
-        assertEquals("6", factorial(3).toString());
-        assertEquals("3628800", factorial(10).toString());
-        assertEquals("2432902008176640000", factorial(20).toString());
-    }
-
-    /**
-     * Calculate the factorial (n!) of a number.
-     * This implementation uses a naive multiplication loop, and
-     * is very slow for large n.
-     * For n = 1000, it takes about 10 ms.
-     * For n = 8000, it takes about 800 ms.
-     *
-     * @param n the number
-     * @return the factorial of n
-     */
-    public static BigInteger factorial(int n) {
-        if (n < 0) {
-            throw new IllegalArgumentException(n + "<0");
-        } else if (n < 2) {
-            return BigInteger.ONE;
-        }
-        BigInteger x = new BigInteger("" + n);
-        BigInteger result = x;
-        for (int i = n - 1; i >= 2; i--) {
-            x = x.subtract(BigInteger.ONE);
-            result = result.multiply(x);
-        }
-        return result;
-    }
-
 }