I am trying to test this class (describeBooksBy) but it keeps giving me a failed test every time. the java class is Library.

public class Book {

private @Nonnull String author;

private @Nonnull String title;

private @CheckForNull String subtitle;

public @Nonnull String getAuthor() {

return author;

}

public @Nonnull String getSubtitle() {

return subtitle;

}

public @Nonnull String getTitle() {

return title;

}

}

public class Library {

public @Nonnull Iterable describeBooksBy(@Nonnull String author) {

List result = new ArrayList();

for (Book b : books) {

if (!author.equals(b.getAuthor())) continue;

result.add(String.format("%s: %d", b.getAuthor(), b.getTitle()));

}

return result;

}

The test I am trying to do is this:

public class LibraryTest {

public LibraryTest() {

}

@BeforeClass

public static void setUpClass() {

}

@AfterClass

public static void tearDownClass() {

}

/**

* Test of describeBooksBy method, of class Library.

*/

@Test

public void test() {

System.out.println("describeBooksBy");

List result = new ArrayList();

result.add("author1");

String author = "";

Library instance = new Library();

instance.describeBooksBy(author);

Iterable result = instance.describeBooksBy(author);

assertEquals(author, result);

}

}

not sure where I am failing to make it pass