Made the tests in MainPresenter be more specific & made the RandomBookGenerator methods not static to make it mockable.

.idea/modules.xml

@@ -5,7 +5,6 @@
       <module fileurl="file://$PROJECT_DIR$/BookLibrary.iml" filepath="$PROJECT_DIR$/BookLibrary.iml" />
       <module fileurl="file://$PROJECT_DIR$/android-bdd-sample-using-cucumber.iml" filepath="$PROJECT_DIR$/android-bdd-sample-using-cucumber.iml" />
       <module fileurl="file://$PROJECT_DIR$/app/app.iml" filepath="$PROJECT_DIR$/app/app.iml" />
-      <module fileurl="file://$PROJECT_DIR$/app/app.iml" filepath="$PROJECT_DIR$/app/app.iml" />
     </modules>
   </component>
 </project>

app/build.gradle

@@ -27,6 +27,8 @@ android {
 dependencies {
     compile fileTree(dir: 'libs', include: ['*.jar'])
 
+    androidTestCompile 'org.mockito:mockito-core:2.5.5'
+    androidTestCompile 'com.linkedin.dexmaker:dexmaker-mockito:2.2.0'
     androidTestCompile ('com.android.support.test.espresso:espresso-core:2.2.1') {
         exclude module: 'support-annotations'
     }

app/src/androidTest/java/com/codemate/booklibrary/RecyclerViewAssertions.java

@@ -13,7 +13,6 @@ import static org.junit.Assert.assertTrue;
  * Created by ironman on 02/09/16.
  */
 public class RecyclerViewAssertions {
-
     public static ViewAssertion adapterItemCountEquals(int count) {
         return new ItemCountAssertion(ItemCountAssertion.MODE_EQUALS, count);
     }

app/src/androidTest/java/com/codemate/booklibrary/ui/MainActivityTest.java

@@ -19,7 +19,10 @@ import static com.codemate.booklibrary.RecyclerViewAssertions.adapterItemCountEq
 import static com.codemate.booklibrary.RecyclerViewAssertions.adapterItemCountLowerThan;
 
 /**
- * Created by ironman on 02/09/16.
+ * Some really coarse UI tests.
+ *
+ * Check the MainPresenterTest for more specific tests that ensure correct books are
+ * returned.
  */
 @RunWith(AndroidJUnit4.class)
 public class MainActivityTest {

app/src/main/java/com/codemate/booklibrary/data/Library.java

@@ -39,7 +39,7 @@ public class Library {
         return results;
     }
 
-    public List<Book> findBooksByAuthor(String authorQuery) {
+    private List<Book> findBooksByAuthor(String authorQuery) {
         List<Book> results = new ArrayList<>();
 
         for (Book candidate : inventory) {
@@ -54,7 +54,7 @@ public class Library {
         return results;
     }
 
-    public List<Book> findBooksByTitle(String titleQuery) {
+    private List<Book> findBooksByTitle(String titleQuery) {
         List<Book> results = new ArrayList<>();
 
         for (Book candidate : inventory) {
@@ -69,7 +69,7 @@ public class Library {
         return results;
     }
 
-    public List<Book> findBooksByYear(String searchedYear) {
+    private List<Book> findBooksByYear(String searchedYear) {
         List<Book> results = new ArrayList<>();
 
         for (Book candidate : inventory) {

app/src/main/java/com/codemate/booklibrary/data/RandomBookGenerator.java

@@ -9,8 +9,6 @@ import java.util.List;
  * Created by ironman on 02/09/16.
  */
 public class RandomBookGenerator {
-    private RandomBookGenerator() {}
-
     private static final String[] SUBJECTS = {
             "Chicken", "Pig", "Hippo", "Dinosaur", "Giraffe", "Orangutan",
             "Bat", "Lion", "Daddy", "Grandpa", "Donald Trump", "Coffee",
@@ -40,7 +38,7 @@ public class RandomBookGenerator {
      * @param howMany how many random books should the generator generate.
      * @return a list that has as many books as the parameter howMany specifies.
      */
-    public static List<Book> generate(int howMany) {
+    public List<Book> generate(int howMany) {
         List<Book> books = new ArrayList<>();
 
         for (int i = 0; i < howMany; i++) {
@@ -53,7 +51,7 @@ public class RandomBookGenerator {
     /**
      * Generates a random book.
      */
-    public static Book randomBook() {
+    public Book randomBook() {
         String title = randomTitle();
         String author = randomAuthor();
         Date date = randomDate();

app/src/main/java/com/codemate/booklibrary/ui/MainActivity.java

@@ -1,5 +1,6 @@
 package com.codemate.booklibrary.ui;
 
+import android.support.annotation.VisibleForTesting;
 import android.support.v7.app.AppCompatActivity;
 import android.os.Bundle;
 import android.support.v7.widget.LinearLayoutManager;
@@ -9,11 +10,14 @@ import android.support.v7.widget.SearchView;
 import com.codemate.booklibrary.data.Book;
 import com.codemate.booklibrary.data.Library;
 import com.codemate.booklibrary.R;
+import com.codemate.booklibrary.data.RandomBookGenerator;
 
 import java.util.List;
 
 public class MainActivity extends AppCompatActivity implements MainView, SearchView.OnQueryTextListener {
-    private MainPresenter presenter;
+    @VisibleForTesting
+    MainPresenter presenter;
+
     private BookAdapter bookAdapter;
 
     @Override
@@ -23,8 +27,8 @@ public class MainActivity extends AppCompatActivity implements MainView, SearchV
 
         initializeViews();
 
-        presenter = new MainPresenter(this, new Library());
+        presenter = new MainPresenter(this, new Library(), new RandomBookGenerator());
-        presenter.loadAllBooks();
+        presenter.fetchBooks();
     }
 
     private void initializeViews() {

app/src/main/java/com/codemate/booklibrary/ui/MainPresenter.java

@@ -1,5 +1,7 @@
 package com.codemate.booklibrary.ui;
 
+import android.support.annotation.VisibleForTesting;
+
 import com.codemate.booklibrary.data.Book;
 import com.codemate.booklibrary.data.Library;
 import com.codemate.booklibrary.data.RandomBookGenerator;
@@ -13,27 +15,27 @@ public class MainPresenter {
     private final MainView mainView;
     private final Library library;
 
-    public MainPresenter(MainView mainView, Library library) {
+    @VisibleForTesting
+    RandomBookGenerator bookGenerator;
+
+    public MainPresenter(MainView mainView, Library library, RandomBookGenerator bookGenerator) {
         this.mainView = mainView;
         this.library = library;
+        this.bookGenerator = bookGenerator;
     }
 
     public void searchForBooks(String searchQuery) {
         List<Book> searchResults = library.search(searchQuery);
-        loadBooks(searchResults);
+        mainView.showBooks(searchResults);
     }
 
-    public void loadAllBooks() {
+    public void fetchBooks() {
         // Populate the library with fake dummy data. In a real app
         // we would have an interactor that would fetch the books from
         // a real API.
-        List<Book> books = RandomBookGenerator.generate(45);
+        List<Book> books = bookGenerator.generate(45);
         library.addBooks(books);
 
-        loadBooks(library.getAllBooks());
+        mainView.showBooks(library.getAllBooks());
-    }
-
-    public void loadBooks(List<Book> books) {
-        mainView.showBooks(books);
     }
 }

app/src/test/java/com/codemate/booklibrary/data/LibraryTest.java

@@ -11,7 +11,7 @@ import java.util.List;
 public class LibraryTest {
     @Test
     public void addMultipleBooks_PersistsThemInLibrary() {
-        List<Book> books = RandomBookGenerator.generate(3);
+        List<Book> books = new RandomBookGenerator().generate(3);
         Library library = new Library();
         library.addBooks(books);
 

app/src/test/java/com/codemate/booklibrary/data/RandomBookGeneratorTest.java

@@ -14,7 +14,7 @@ import static org.junit.Assert.assertNotNull;
 public class RandomBookGeneratorTest {
     @Test
     public void generatingRandomBooks_ReturnsNonEmptyBookList() {
-        List<Book> books = RandomBookGenerator.generate(15);
+        List<Book> books = new RandomBookGenerator().generate(15);
 
         assertEquals(15, books.size());
 

app/src/test/java/com/codemate/booklibrary/ui/MainPresenterTest.java

@@ -9,9 +9,12 @@ import org.junit.Test;
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 
+import java.sql.Date;
+import java.util.Arrays;
 import java.util.List;
 
-import static org.mockito.Matchers.anyString;
+import static java.util.Collections.singletonList;
+import static org.mockito.ArgumentMatchers.anyInt;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
@@ -19,36 +22,40 @@ import static org.mockito.Mockito.when;
  * Created by ironman on 02/09/16.
  */
 public class MainPresenterTest {
+    private static final List<Book> DUMMY_BOOKS = Arrays.asList(
+            new Book("Sample book one", "John Doe", Date.valueOf("2000-10-25")),
+            new Book("Sample book two", "Jane Doe", Date.valueOf("2016-01-01")),
+            new Book("Sample book three", "Some One", Date.valueOf("2005-12-12"))
+    );
+
     @Mock
     private MainView mainView;
 
     @Mock
-    private Library library;
+    private RandomBookGenerator bookGenerator;
 
     private MainPresenter presenter;
-    private List<Book> randomBooks;
 
     @Before
     public void setUp() {
         MockitoAnnotations.initMocks(this);
 
-        presenter = new MainPresenter(mainView, library);
+        when(bookGenerator.generate(anyInt())).thenReturn(DUMMY_BOOKS);
-        randomBooks = RandomBookGenerator.generate(5);
+        presenter = new MainPresenter(mainView, new Library(), bookGenerator);
     }
 
     @Test
-    public void searchForBooks_ShowsThemInUI() {
+    public void searchForBooks_WhenSearchingByAuthorJohn_ShowsFirstBookInUI() {
-        when(library.search(anyString())).thenReturn(randomBooks);
+        presenter.fetchBooks();
-        presenter.searchForBooks("test_search");
+        presenter.searchForBooks("John");
 
-        verify(mainView).showBooks(randomBooks);
+        verify(mainView).showBooks(singletonList(DUMMY_BOOKS.get(0)));
     }
 
     @Test
-    public void loadAllBooks_ShowsThemInUI() {
+    public void fetchBooks_LoadsAll_AndShowsThemInUI() {
-        when(library.getAllBooks()).thenReturn(randomBooks);
+        presenter.fetchBooks();
-        presenter.loadAllBooks();
 
-        verify(mainView).showBooks(randomBooks);
+        verify(mainView).showBooks(DUMMY_BOOKS);
     }
 }

app/src/test/resources/com.codemate.booklibrary/booksearch.feature

@@ -4,14 +4,14 @@ Feature: Book Search
   Background:
     Given the library has a book with title "How to be awesome", written by "Iiro Krankka", published in 16 May 2016
     And a book with title "My life as an awesome guy", written by "Iiro Krankka", published in 27 July 2016
-    And a book with title "I think my teacher is an asshat", written by "John Doe", published in 01 January 2010
+    And a book with title "I think my teacher is cool", written by "John Doe", published in 01 January 2010
 
   Scenario: List all books
     When the customer wants to know all books in the library
     Then 3 books should be found
       And Book 1 should have the title "How to be awesome"
       And Book 2 should have the title "My life as an awesome guy"
-      And Book 3 should have the title "I think my teacher is an asshat"
+      And Book 3 should have the title "I think my teacher is cool"
 
   Scenario: Search books by year
     When the customer searches for books published in year 2016
@@ -39,5 +39,5 @@ Feature: Book Search
     Examples:
       | Title Search   | Number of Results    | Found Books                                         |
       | "Awesome"      | 2                    | "How to be awesome" and "My life as an awesome guy" |
-      | "asshat"       | 1                    | "I think my teacher is an asshat"                   |
+      | "cool"         | 1                    | "I think my teacher is cool"                        |
       | "How to be"    | 1                    | "How to be awesome"                                 |