### Question:
OpPeruseConfiguration implements CheckstyleCommand<Void> { @Override public Void execute(@NotNull final Project project) throws CheckstyleException { runVisitor(configuration); return null; } OpPeruseConfiguration(@NotNull final CheckstyleInternalObject configuration,
                                 @NotNull final ConfigVisitor visitor); @Override Void execute(@NotNull final Project project);  }### Answer:
@Test public void testNullConfig() throws CheckstyleException { final OpPeruseConfiguration cmd = new OpPeruseConfiguration(new CsConfigObject(null), new StubVisitor()); assertNull(cmd.execute(PROJECT)); }