Unit Test your code, even your UI

Unit Test your code,
even your UI
@stan_kocken

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Testing
Instrumentation (on Android Device)
Unit Tests (on JVM)

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Unit Testing on JVM
Run quickly
Allow TDD (Test Driven Development)
Easy to add on your build process (CI)

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app
↳ src
↳ main
↳ test
↳ java
↳ com.skocken.junittest
↳ ExampleUnitTest
Test hierarchy

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Build Variants
Android Studio
Conﬁgure
View > Tools Windows >
Test Artifact: Android Instrumentation Tests
Unit Tests

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Android Studio
Execute
app
↳ src
↳ main
↳ test
↳ java
↳ ExampleUnitTest
Right click
> Run ‘All tests’
(or Run ‘Junit’)

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Gradle
Execute
./gradlew testDebugUnitTest
…
BUILD SUCCESSFUL
Total time: 2.057 secs
test{flavor}{build_type}UnitTest

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app
↳ src
↳ main
↳ test
↳ java
↳ ExampleUnitTest
public class ExampleUnitTest { 
@Test 
public void addition_isCorrect() throws Exception { 
assertEquals(4, 2 + 2); 
} 
}
OK

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TDD
Add a test
Run (should fail)
Write code to ﬁx it
Run (should succeed)
Refactor code
(Test Driven Development)

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Basic class
public class Plane { 
 
private final String mName; 
 
public Plane(String name) { 
mName = name; 
} 
 
}
Alt + Enter
> Create Test
> JUnit4

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Basic test
public class PlaneTest { 
 
 
}
 
@Test 
public void testShouldCompareName() { 
Plane plane = new Plane("A380"); 
assertTrue(plane.sameAs("A380")); 
assertFalse(plane.sameAs("B747")); 
}
Alt + Enter
> Create method ‘sameAs’

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Add ‘sameAs’
 
 
mName = name; 
}
 
 
}
 
public boolean sameAs(String name) { 
return false; 
} 

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Run Test
public class PlaneTest {
 
@Test 
}
}
!

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Fix ‘sameAs’
 
 
mName = name; 
}
 
public boolean sameAs(String name) { 
return false;
 
} 
 
}
// return false;
return name != null && name.equals(mName);

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Run Test
 
@Test 
}
}
OK

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Add some Android logs
 
 
mName = name; 
}
 
public boolean sameAs(String name) {
 
return name != null && name.equals(mName); 
} 
 
}
Log.v("Plane", "compare with: " + name);

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Run Test
 
@Test 
}
}
!
java.lang.RuntimeException: Method v in android.util.Log not mocked.
at android.util.Log.v(Log.java)
at com.skocken.junittest.Plane.sameAs(Plane.java:14)
at com.skocken.junittest.PlaneTest.testShouldCompareName(PlaneTest.java:13)

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Mock android.jar - build.gradle
android { 
…
testOptions { 
unitTests.returnDefaultValues = true 
} 
}

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Run Test
 
@Test 
}
}
OK

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Run Test, with “null”
 
@Test 
public void testShouldCompareName() { … } 
 
@Test 
public void testShouldCompareNameNull() { 
Plane plane = new Plane(null); 
assertTrue(plane.sameAs(null)); 
} 
 
}
!

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Fix ‘sameAs’
 
 
mName = name; 
}
 
public boolean sameAs(String name) {
Log.v("Plane", "compare with: " + name); 
return name != null && name.equals(mName);
 
} 
 
}
// return name != null && name.equals(mName);
return TextUtils.equals(mName, name);

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Run Test
 
@Test 
public void testShouldCompareName() {
assertFalse(plane.sameAs(“B747"));
} 
 
@Test 
public void testShouldCompareNameNull() { 
Plane plane = new Plane(null); 
assertTrue(plane.sameAs(null)); 
} 
 
}
!

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build.gradle
android { 
…
testOptions { 
unitTests.returnDefaultValues = true 
} 
}
public static boolean equals(CharSequence a, CharSequence b) { 
… 
}
public static boolean equals(CharSequence a, CharSequence b) { 
return false; 
}
TextUtils.java
Mock of TextUtils.java

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Solutions
TextUtils → custom method
(or library like Apache Common)
Need to replace every calls
More code “duplicate”
“just because” of the test
Tests clean, no change

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Solutions
Robolectric
Not “exactly” Android
A bit slower (~ +3sec)
No change on code to test

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Example

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Board
play(Player player, int x, int y)
Player getPlayer(int x, int y)
int getPlayLeft()
Player getWinner()

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Tests
public class GameBoardTest extends TestCase {
 
private GameBoard mSubject;
 
@Before 
public void setUp() throws Exception { 
mSubject = new GameBoard(); 
}
 
@Test 
public void testSetPlayer() throws Exception {
assertEquals(GameBoard.Player.EMPTY, mSubject.getPlayer(0, 0));
mSubject.play(GameBoard.Player.J1, 0, 0);
assertEquals(GameBoard.Player.J1, mSubject.getPlayer(0, 0)); 
}
 
}
Fix your tests now

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Tests
public class GameBoardTest extends TestCase { 
 
private GameBoard mSubject; 
 
@Before 
} 
 
@Test 
public void testSetPlayer() throws Exception { … } 
 
@Test 
public void testGetNbPlayLeft() throws Exception { 
assertEquals(9, mSubject.getNbPlayLeft()); 
mSubject.play(GameBoard.Player.J1, 2, 2); 
} 
 
}
Fix your tests now

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Tests
public class GameBoardTest extends TestCase { 
 
private GameBoard mSubject; 
 
@Before 
} 
 
… 
 
@Test 
public void testGetWinnerInCol() throws Exception { 
assertNull(mSubject.getWinner()); 
assertEquals(mSubject.getWinner(), GameBoard.Player.J1); 
} 
 
}
Fix your tests now

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AI
constructor: (GameBoard board, Player aiPlayer)
playNext()

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Tests
public class AITest extends TestCase { 
 
private static final GameBoard.Player PLAYER_AI = GameBoard.Player.J2; 
 
private GameBoard mGameBoard; 
 
private AI mAI; 
 
@Before 
mGameBoard = new GameBoard(); 
mAI = new AI(mGameBoard, PLAYER_AI); 
} 
 
}

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Tests
public class AITest extends TestCase {
 
… 
Fix your tests now
@Test 
public void testPlayNextWithEmpty() throws Exception { 
GameBoard.Player[][] initBoard = 
{ 
{__, __, __}, 
{__, __, __}, 
{__, __, __} 
 
}; 
mGameBoard.setBoard(initBoard); 
mAI.playNext();
assertEquals(PLAYER_AI, mGameBoard.getPlayer(1, 1)); 
} 
 
}

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Tests
@Test 
public void testPlayWinnerMove() throws Exception { 
GameBoard.Player[][] initBoard = 
{ 
{J1, IA, J1}, 
{IA, IA, J1}, 
{J1, __, __} 
 
}; 
mGameBoard.setBoard(initBoard); 
 
mIA.playNext();
 
assertEquals(IA, mGameBoard.getPlayer(1, 2)); 
assertEquals(IA, mGameBoard.getWinner()); 
} 
 
}
Fix your tests now
public class AITest extends TestCase {
 
… 

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Go Further
Improve your AI
Increase board size
…

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Android UI

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Activity

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BaseActivity:1600+ lines
A base activity that handles common
functionality in the app. This includes the
navigation drawer, login and authentication,
Action Bar tweaks, amongst others.

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God Object

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How to do differently?
View Proxy
Touch Android View
No business logic
DataProvider
Access Data
Store state
Presenter
Data to ViewProxy

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Architecture
Presenter
DataProvider ViewProxy
Activity View
Strong Reference
Weak Reference
Other “Strong” Reference on DataProvider, Presenter or
ViewProxy forbidden. Use WeakReference.
OK

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Example

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v1: Activity
public class OriginalActivity extends Activity 
implements View.OnClickListener { 
 
private final GameBoard mGameBoard = new GameBoard(); 
 
private final GameBoard.Player mCurrentPlayer = GameBoard.Player.J1; 
 
private final AI mAI = new AI(mGameBoard, GameBoard.Player.J2); 
 
private ViewGroup mBoxesLayout; 
 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
super.onCreate(savedInstanceState); 
setContentView(R.layout.activity_main); 
mBoxesLayout = (ViewGroup) findViewById(R.id.boxes_layout); 
} 
 
@Override 
protected void onResume() { 
super.onResume(); 
refreshBoard(); 
} 
 
@Override 
public void onClick(View v) { 
Object x = v.getTag(R.id.tag_x); 
Object y = v.getTag(R.id.tag_y); 
if (x instanceof Integer && y instanceof Integer) { 
play((int) x, (int) y); 
} 
} 
 
private void play(int x, int y) { 
mGameBoard.play(mCurrentPlayer, x, y); 
mAI.playNext(); 
refreshBoard(); 
}
private void refreshBoard() { 
int size = mGameBoard.getSize(); 
for (int y = 0; y < size; y++) { 
for (int x = 0; x < size; x++) { 
GameBoard.Player player = mGameBoard.getPlayer(x, y); 
 
int boxType; 
switch (player) { 
case EMPTY: 
boxType = BoardDef.BOX_EMPTY; 
break; 
case J1: 
boxType = BoardDef.BOX_CROSS; 
break; 
case J2: 
boxType = BoardDef.BOX_ROUND; 
break; 
default: 
continue; 
} 
setBoxValue(x, y, boxType); 
} 
} 
} 
 
private void setBoxValue(int x, int y, int boxType) { 
ViewGroup rowLayout = (ViewGroup) mBoxesLayout.getChildAt(y); 
View boxView = rowLayout.getChildAt(x); 
 
int bgColor; 
switch (boxType) { 
case BoardDef.BOX_CROSS: 
bgColor = Color.RED; 
boxView.setOnClickListener(null); 
break; 
case BoardDef.BOX_ROUND: 
bgColor = Color.BLUE; 
break; 
default: 
bgColor = Color.GRAY; 
boxView.setOnClickListener(this); 
break; 
} 
boxView.setBackgroundColor(bgColor); 
boxView.setTag(R.id.tag_x, x); 
boxView.setTag(R.id.tag_y, y); 
} 
}

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DataProvider Presenter ViewProxy
v2: Creation
refreshBoard()
getGameBoard() setBoxValue(
int x, int y,
int boxType);

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DataProvider Presenter ViewProxy
v2: User click box
onSelectBox(int x, int y)
play(int x, int y)
refreshBoard()
…

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v2: Deﬁnition
public interface BoardDef { 
 
int BOX_EMPTY = 0; 
 
int BOX_CROSS = 1; 
 
int BOX_ROUND = 2; 
 
interface IPresenter extends BaseDef.IPresenter { 
 
void refreshBoard(); 
 
void onSelectBox(int x, int y); 
} 
 
interface IDataProvider extends BaseDef.IDataProvider { 
 
GameBoard getGameBoard(); 
 
void play(int x, int y); 
} 
 
interface IView extends BaseDef.IView { 
 
void setBoxValue(int x, int y, int boxType); 
} 
}

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v2: DataProvider
public class BoardDataProvider 
extends BaseDataProvider 
implements BoardDef.IDataProvider { 
 
private final GameBoard mGameBoard = new GameBoard(); 
 
private final GameBoard.Player mCurrentPlayer =
GameBoard.Player.J1; 
 
private final AI mAI = new AI(mGameBoard,
GameBoard.Player.J2); 
 
@Override 
public GameBoard getGameBoard() { 
return mGameBoard; 
} 
 
@Override 
public void play(int x, int y) { 
mGameBoard.play(mCurrentPlayer, x, y); 
mAI.playNext(); 
getPresenter().refreshBoard(); 
} 
} 

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public class BoardPresenter  
extends BasePresenter 
implements BoardDef.IPresenter { 
 
public BoardPresenter(Activity activity, 
BoardDef.IDataProvider provider, BoardDef.IView view) { 
super(activity, provider, view); 
} 
 
@Override 
public void onResume() { 
refreshBoard(); 
} 
 
@Override 
public void onSelectBox(int x, int y) { 
getProvider().play(x, y); 
} 
 
@Override 
public void refreshBoard() { 
GameBoard gameBoard = getProvider().getGameBoard(); 
int size = gameBoard.getSize(); 
for (int y = 0; y < size; y++) { 
for (int x = 0; x < size; x++) { 
setBoxValue(gameBoard, y, x); 
} 
} 
}
v2: Presenter

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public class BoardPresenter  
extends BasePresenter 
implements BoardDef.IPresenter { 
 
public BoardPresenter(Activity activity, 
BoardDef.IDataProvider provider, BoardDef.IView view) { 
super(activity, provider, view); 
} 
 
@Override 
public void onResume() { 
refreshBoard(); 
} 
 
@Override 
public void onSelectBox(int x, int y) { 
getProvider().play(x, y); 
} 
 
@Override 
public void refreshBoard() { 
GameBoard gameBoard = getProvider().getGameBoard(); 
int size = gameBoard.getSize(); 
for (int y = 0; y < size; y++) { 
for (int x = 0; x < size; x++) { 
setBoxValue(gameBoard, y, x); 
} 
} 
}
v2: Presenter
private void setBoxValue(GameBoard gameBoard, int y, int x) { 
GameBoard.Player player = gameBoard.getPlayer(x, y); 
int boxValue; 
switch (player) { 
case EMPTY: 
boxValue = BoardDef.BOX_EMPTY; 
break; 
case J1: 
boxValue = BoardDef.BOX_CROSS; 
break; 
case J2: 
boxValue = BoardDef.BOX_ROUND; 
break; 
default: 
return; 
} 
getView().setBoxValue(x, y, boxValue); 
} 
}

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public class BoardViewProxy extends BaseViewProxy 
implements BoardDef.IView, View.OnClickListener { 
 
public BoardViewProxy(Activity activity) { 
super(activity); 
} 
 
@Override 
int x = (Integer) v.getTag(R.id.tag_x); 
int y = (Integer) v.getTag(R.id.tag_y); 
getPresenter().onSelectBox(x, y); 
}
v2: ViewProxy
@Override 
public void setBoxValue(int x, int y, int boxType) { 
ViewGroup boxLayout = findViewByIdEfficient(R.id.boxes_layout); 
ViewGroup rowLayout = (ViewGroup) boxLayout.getChildAt(y); 
 
int bgColor; 
break; 
break; 

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public class BoardViewProxy extends BaseViewProxy 
implements BoardDef.IView, View.OnClickListener { 
 
public BoardViewProxy(Activity activity) { 
super(activity); 
} 
 
@Override 
int x = (Integer) v.getTag(R.id.tag_x); 
int y = (Integer) v.getTag(R.id.tag_y); 
getPresenter().onSelectBox(x, y); 
}
v2: ViewProxy
@Override 
public void setBoxValue(int x, int y, int boxType) { 
ViewGroup boxLayout = findViewByIdEfficient(R.id.boxes_layout); 
ViewGroup rowLayout = (ViewGroup) boxLayout.getChildAt(y); 
 
int bgColor; 
break; 
break; 
default: 
bgColor = Color.GRAY; 
boxView.setOnClickListener(this); 
break; 
} 
boxView.setBackgroundColor(bgColor); 
boxView.setTag(R.id.tag_x, x); 
boxView.setTag(R.id.tag_y, y); 
}
}

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Improve clarity
To test it easily!
Why split my god object
Activity?

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Tests: setup
public class BoardDataProviderTest extends TestCase { 
 
private BoardDef.IPresenter mPresenter; 
 
private BoardDataProvider mDataProvider; 
 
@Before 
mPresenter = Mockito.mock(BoardDef.IPresenter.class); 
 
mDataProvider = new BoardDataProvider(); 
mDataProvider.setPresenter(mPresenter); 
}

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Tests: setup
public class BoardPresenterTest extends TestCase { 
 
private BoardDef.IDataProvider mDataProvider; 
 
private BoardDef.IView mBoardView; 
 
private BoardPresenter mBoardPresenter; 
 
@Before 
mDataProvider = Mockito.mock(BoardDef.IDataProvider.class); 
mBoardView = Mockito.mock(BoardDef.IView.class); 
 
mBoardPresenter = new BoardPresenter(mDataProvider, mBoardView); 
}

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Tests: setup
public class BoardViewProxyTest extends TestCase { 
 
private View mContentView; 
 
private BoardDef.IPresenter mPresenter; 
 
private BoardViewProxy mViewProxy; 
 
@Before 
mPresenter = Mockito.mock(BoardDef.IPresenter.class); 
 
mContentView = Mockito.mock(View.class); 
Activity mockActivity = Mockito.mock(Activity.class); 
when(mockActivity.findViewById(android.R.id.content)) 
.thenReturn(mContentView); 
 
mViewProxy = new BoardViewProxy(mockActivity); 
mViewProxy.setPresenter(mPresenter); 
}

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Test the UI
Android stuffs
TextView
ImageView
…
View Proxy
Already Tested by
framework team

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Test the UI
View Proxy Mock
Mock
Mock

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Tests ViewProxy
@Test 
public void testSetBoxValue() throws Exception {
ViewGroup boxesViewGroup = Mockito.mock(ViewGroup.class);
when(mContentView.findViewById(R.id.boxes_layout)).thenReturn(boxesViewGroup); 
ViewGroup firstRowViewGroup = Mockito.mock(ViewGroup.class);
ViewGroup secondRowViewGroup = Mockito.mock(ViewGroup.class);
ViewGroup thirdRowViewGroup = Mockito.mock(ViewGroup.class);
when(boxesViewGroup.getChildAt(0)).thenReturn(firstRowViewGroup);
when(boxesViewGroup.getChildAt(1)).thenReturn(secondRowViewGroup);
when(boxesViewGroup.getChildAt(2)).thenReturn(thirdRowViewGroup); 
View firstRowFirstColView = Mockito.mock(View.class); 
View secondRowSecondColView = Mockito.mock(View.class); 
View thirdRowSecondColView = Mockito.mock(View.class); 
when(firstRowViewGroup.getChildAt(0)).thenReturn(firstRowFirstColView); 
when(secondRowViewGroup.getChildAt(1)).thenReturn(secondRowSecondColView); 
when(thirdRowViewGroup.getChildAt(1)).thenReturn(thirdRowSecondColView); 
mViewProxy.setBoxValue(0, 0, BoardDef.BOX_CROSS); 
mViewProxy.setBoxValue(1, 1, BoardDef.BOX_ROUND); 
mViewProxy.setBoxValue(1, 2, BoardDef.BOX_EMPTY); 
assertBackgroundColor(Color.RED, firstRowFirstColView); 
assertBackgroundColor(Color.BLUE, secondRowSecondColView); 
assertBackgroundColor(Color.GRAY, thirdRowSecondColView); 
} 
private void assertBackgroundColor(int expectedColor, View view) { 
ArgumentCaptor colorArg = ArgumentCaptor.forClass(Integer.class); 
verify(view).setBackgroundColor(colorArg.capture()); 
assertEquals("The background expectedColor is not correct", 
expectedColor, (int) colorArg.getValue()); 
}

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Code Coverage
Highlight part of code not tested
The percentage is (quite) useless
Display in Android Studio

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Android Studio
Execute
app
↳ src
↳ main
↳ test
↳ java
↳ ExampleUnitTest
Right click
> Run ‘All tests’ with Coverage
(or Run ‘Junit’ with Coverage)

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Singleton
Goal: be able to mock it

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Common Singleton patterns
public class MyManager { 
 
private static class SingletonHolder { 
 
private static final MyManager INSTANCE = new MyManager(); 
} 
 
private MyManager() { 
} 
 
public static MyManager getInstance() { 
return SingletonHolder.INSTANCE; 
} 
 
public void myMethod() { 
 
} 
}
Testable?
// or
public enum MyManager { 
INSTANCE; 
 
} 
}

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My testable Singleton pattern
public class MyManager { 
 
private MyManager() { 
} 
 
public static MyManager getInstance() { 
return Singleton.getInstance(MyManager.class); 
} 
 
} 
}

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Test
public class GameBoard { 
 
... 
 
MyManager.getInstance().myMethod(); 
} 
 
}
public class GameBoardTest extends TestCase {
 
... 
 
@Test 
public void testShouldCallMockSingleton() {
MyManager managerMock = Mockito.mock(MyManager.class);
Singleton.setInstance(MyManager.class, managerMock); 
mSubject.myMethod();
verify(managerMock, times(1)).myMethod(); 
} 
 
}

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Credits
@stan_kocken
Presentation pattern: github.com/StanKocken/Presentation
TicTacToe Example: github.com/StanKocken/TicTacToe
Singleton: github.com/StanKocken/39d604bcf8c814a48859
Leak Canary: github.com/square/leakcanary
Presentation pattern co-writer: Marc Olory

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Unit Test your code, even your UI

Unit Test your code, even your UI

Stan Kocken

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