### Question:
Services { public static Services getDefault() { return INSTANCE; } Services(Require require, Global global, Worker worker); static Services getDefault(); void postInit(Algorithms newAlgorithms); BigInteger factorial(int value);  }### Answer:
@Test public void testRubyFactorial() { String n = Services.getDefault().algorithms.ruby(3); assertEquals("Factorial of 3", "6", n); }
@Test public void testJavaScriptFactorial() { Number n = Services.getDefault().algorithms.js(3); assertEquals("Factorial of 3", 6, n.intValue()); }
@Test public void testRLanguageFactorial() { Number n = Services.getDefault().algorithms.r(3); assertEquals("Factorial of 3", 6, n.intValue()); }