@Test
public void callTheSpinAndWarmUpMethods() throws Exception {
Method accessor = checkThatSingletonContainsStaticInstanceAccessorMethod(Earth.class);
Earth earth = (Earth) accessor.invoke(null);
earth.spin();
earth.warmUp();
}
@Test
public void testThatAccessorAlwaysReturnsSameInstance() throws Exception {
Method accessor = checkThatSingletonContainsStaticInstanceAccessorMethod(Earth.class);
Earth earth1 = (Earth) accessor.invoke(null);
Earth earth2 = (Earth) accessor.invoke(null);
assertSame("Instances returned should be the same", earth1, earth2);
}
@Test
public void checkThatOtherMethodsAreNonStatic() throws NoSuchMethodException {
Method spin = Earth.class.getDeclaredMethod("spin");
assertFalse("Method spin() should not be static", Modifier.isStatic(spin.getModifiers()));
Method warmUp = Earth.class.getDeclaredMethod("warmUp");
assertFalse("Method warmUp() should not be static", Modifier.isStatic(warmUp.getModifiers()));
}
private Method checkThatSingletonContainsStaticInstanceAccessorMethod(Class clazz) {
for (Method method : clazz.getDeclaredMethods()) {
if (method.getReturnType() == clazz && method.getParameterTypes().length == 0) {
assertTrue(
"Method returning the Earth instance should be static",
Modifier.isStatic(method.getModifiers()));
return method;
}
}
fail("No static accessor method found.");
return null; // will never be called.
}