### Question:
RealFunctionIntegrator1DFactory { public static String getIntegratorName(Integrator1D<Double, Double> integrator) { if (integrator == null) { return null; } return INSTANCE_NAMES.get(integrator.getClass()); } private  RealFunctionIntegrator1DFactory(); static Integrator1D<Double, Double> getIntegrator(String integratorName); static String getIntegratorName(Integrator1D<Double, Double> integrator); static final String ROMBERG; static final RombergIntegrator1D ROMBERG_INSTANCE; static final String SIMPSON; static final SimpsonIntegrator1D SIMPSON_INSTANCE; static final String EXTENDED_TRAPEZOID; static final ExtendedTrapezoidIntegrator1D EXTENDED_TRAPEZOID_INSTANCE; }### Answer:
@Test public void testNullCalculator() { assertThat(RealFunctionIntegrator1DFactory.getIntegratorName(null)).isNull(); }