JUnit testcase to test a Map of Map containing class object

Question

I am trying to write a JUnit testcase to test a Map: Map<String, Map<Long, Book>> map. Following is the description of the Book class: - Class Book{ long id; String name; String description; List<Payment> payments; }

Following is the structure of the Payment class. Class Payment{ long id; long payNum; double amount; String paidBy; } I need to assert that the map has following entries: - <"Shelf1", <1L, book1>> <"Shelf2", <5L, book2>> Also, need to verify that: - book1 has id=1L, name="my book", payments={amount=10} book1 has id=5L, name="my book2", payments={amount=50}

I am trying following code: -

`Assertions.assertThat(map)
        .hasSize(2)
        .contains(entry("Shelf1",
            contains(entry(Long.valueOf(1),
                    extracting(Book::getId, Book::getName)
                    .containsExactlyInAnyOrder(
                              tuple(Long.valueOf(1), "my book"),
                              tuple(Long.valueOf(5), "my book2")))))));`

1. I am always getting an error on extracting function call that the method extracting is undefined for Book::getId, Book::getName.
2. In addition, I am not sure how to check the payment entry. Note that the books has only one payment entry.

I tried to solve the assert with the way that I just shared, but that is not working.your text