什么是BDD？

behavior-driven development (BDD)，行为驱动开发。

参考：https://en.wikipedia.org/wiki/Behavior-driven_development

语法区别：

given-willReturn when-thenReturn stub-toReturn

BDDMockito优点：易于阅读

java
    @Test
    public void usingMockito() {
        TodoService todoService = mock(TodoService.class);
        List<String> allTodos = Arrays.asList("Learn Spring MVC",
                "Learn Spring", "Learn to Dance");
        when(todoService.retrieveTodos("Ranga")).thenReturn(allTodos);
        TodoBusinessImpl todoBusinessImpl = new TodoBusinessImpl(todoService);
        List<String> todos = todoBusinessImpl
                .retrieveTodosRelatedToSpring("Ranga");
        assertEquals(2, todos.size());
    }

    @Test
    public void usingMockito_UsingBDD() {
        TodoService todoService = mock(TodoService.class);
        TodoBusinessImpl todoBusinessImpl = new TodoBusinessImpl(todoService);
        List<String> allTodos = Arrays.asList("Learn Spring MVC",
                "Learn Spring", "Learn to Dance");

    //Given - setup
        given(todoService.retrieveTodos("Ranga")).willReturn(allTodos);

        //When - actual method call
        List<String> todos = todoBusinessImpl
                .retrieveTodosRelatedToSpring("Ranga");

        //Then - asserts
        assertThat(todos.size(), is(2));
    }