### Question:
FluentWebElementAssert extends AbstractFluentAssert<FluentWebElementAssert, FluentWebElement> implements ElementStateAssert, ElementAttributeAssert { @Override public FluentWebElementAssert hasNotClass(String htmlClass) { String actualClasses = actual.attribute(CLASS_ATTRIBUTE); if (actualClasses != null && getClasses(actualClasses).contains(htmlClass)) { failWithMessage("The element has class: " + htmlClass); } return this; } FluentWebElementAssert(FluentWebElement actual); @Override FluentWebElementAssert isEnabled(); @Override FluentWebElementAssert isNotEnabled(); @Override FluentWebElementAssert isDisplayed(); @Override FluentWebElementAssert isNotDisplayed(); @Override FluentWebElementAssert isSelected(); @Override FluentWebElementAssert isNotSelected(); @Override FluentWebElementAssert isClickable(); @Override FluentWebElementAssert isNotClickable(); @Override FluentWebElementAssert isPresent(); @Override FluentWebElementAssert isNotPresent(); @Override FluentWebElementAssert hasText(String textToFind); @Override FluentWebElementAssert hasTextContaining(String text); @Override FluentWebElementAssert hasTextMatching(String regexToBeMatched); @Override FluentWebElementAssert hasNotText(String textToFind); @Override FluentWebElementAssert hasNotTextContaining(String textToFind); @Override FluentWebElementAssert hasId(String idToFind); @Override FluentWebElementAssert hasClass(String classToFind); @Override FluentWebElementAssert hasNotClass(String htmlClass); @Override FluentWebElementAssert hasClasses(String... classesToFind); @Override FluentWebElementAssert hasNotClasses(String... classesToFind); @Override FluentWebElementAssert hasValue(String value); @Override FluentWebElementAssert hasName(String name); @Override FluentWebElementAssert hasTagName(String tagName); @Override FluentWebElementAssert hasDimension(Dimension dimension); @Override FluentWebElementAssert hasAttributeValue(String attribute, String value); @Override AbstractStringAssert hasAttribute(String attribute); @Override FluentWebElementAssert hasNotAttribute(String attribute);  }### Answer:
@Test public void shouldNotHaveClass() { when(element.attribute("class")).thenReturn("clazz other-clazz"); elementAssert.hasNotClass("not-class"); }
@Test public void shouldNotHaveClassWhenClassAttributeIsNotPresent() { elementAssert.hasNotClass("clazz"); }
@Test public void shouldFailWhenHasClass() { when(element.attribute("class")).thenReturn("clazz other-clazz"); assertThatAssertionErrorIsThrownBy(() -> elementAssert.hasNotClass("clazz")) .hasMessage("The element has class: clazz"); }