Device fragmentation vs clean code

Device Fragmentation

Clean Code
Iordanis “Jordan” Giannakakis
@iordanis_g
#fragVsCode

Introduction
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Iordanis “Jordan” Giannakakis
Android Team Lead – Shazam
@iordanis_g
#fragVsCode

@iordanis_g #fragVsCode

How Shazam works


Bad vs. good code


How is fragmentation related to
clean code?


Is fragmentation really a problem?

android.support

Is fragmentation really a problem?


Is clean code really a concern?


Is clean code really a concern?

A couple of months later...

SharedPreferences.Editor

• commit() – slow
• apply() – fast


API example – MainActivity
protected void onResume() {
super.onResume();
SharedPreferences sharedPreferences =
PreferenceManager.getDefaultSharedPreferences(this);
SharedPreferences.Editor editor = sharedPreferences.edit();
prefEditor.putBoolean("has_launched_before", true);
// Will only be available for versions after Froyo
if(VERSION.SDK_INT >= VERSION_CODES.GINGERBREAD) {
editor.apply();
} else {
editor.commit();
}
}


Fixed it!


What are the issues?
super.onResume();
Glue
PreferenceManager.getDefaultSharedPreferences(this);
SharedPreferences.Editor editor = sharedPreferences.edit();
Business
prefEditor.putBoolean("has_launched_before", true);

Logic

// Will only be available for versions after Froyo
editor.apply();
} else {
editor.commit();
}

Glue

}


How to unit test?

Good luck!


Dependency Injection


Dependency Injection Framework


New MainActivity

@Override
public void onResume() {
super.onResume();

editor.putBoolean("has_launched_before", true);
preferencesSaver.save(editor);
}


Before & After
super.onResume();
PreferenceManager
.getDefaultSharedPreferences(this);
SharedPreferences.Editor editor =
sharedPreferences.edit();
prefEditor.putBoolean(
"has_launched_before", true);
// Will only be available for versions
after Froyo
if(VERSION.SDK_INT >=
VERSION_CODES.GINGERBREAD) {
editor.apply();
} else {
editor.commit();
}
}

public void onResume() {
super.onResume();
editor.putBoolean(
"has_launched_before", true);
preferencesSaver.save(editor);
}


New MainActivity – Constructors

// Constructor the system will call to instantiate this activity
public MainActivity() {
this(sharedPreferencesEditor(), preferencesSaver());
}

// Constructor that can be used in production and test code
public MainActivity(Editor editor, PreferencesSaver preferencesSaver) {
this.editor = editor;
this.preferencesSaver = preferencesSaver;
}


Module classes
public class SharedPreferencesEditorModule {
public static SharedPreferences.Editor sharedPreferencesEditor() {
Context context = getApplication().getApplicationContext();
SharedPreferences preferences = getDefaultSharedPreferences(context);
Editor editor = preferences.edit();
return editor;
}
}
public class PreferencesSaverModule {
public static PreferencesSaver preferencesSaver() {

return new ApplyPreferencesSaver();
}
return new CommitPreferencesSaver();
}
}


Application
public class MyCoolApplication extends Application {
private static MyCoolApplication application;
@Override
public void onCreate() {
application = this;
}
public static MyCoolApplication getApplication() {
return application;
}

}


How to unit test?
@Mock Editor editor;
@Mock PreferencesSaver saver;
@Test
public void canSaveLaunchFlag() {
mockery.checking(new Expectations() {{
atLeast(1).of(editor).putBoolean("has_launched_before", true);
oneOf(saver).save(editor);
}});
MainActivity activity = new MainActivity(editor, saver);
activity.onResume();
}


Capabilities example – Google+


Capabilities example
public void onCreate(Bundle savedInstanceState) {
// Set layout
View googlePlus = findViewById(R.id.google_plus);
try {
getPackageManager().getApplicationInfo("com.android.vending", 0);
googlePlus.setVisibility(VISIBLE);
} catch (PackageManager.NameNotFoundException e) {
googlePlus.setVisibility(GONE);
}
}


MVP pattern


The Model
public class GooglePlayAvailability {
private PackageManager packageManager;
public GooglePlayAvailability(PackageManager packageManager) {
this.packageManager = packageManager;
}
public boolean googlePlayIsAvailable() {
try {
packageManager.getApplicationInfo("com.android.vending", 0);
return true;
} catch (PackageManager.NameNotFoundException e) {
return false;
}
}
}


The View

public interface GooglePlusView {
public void showGooglePlus();

public void hideGooglePlus();
}


Activity as View
public class MainActivity extends Activity implements GooglePlusView {
public void onCreate(Bundle savedInstanceState) {
//Set layout...
googlePlus = findViewById(R.id.google_plus);
//Injected googlePlusPresenter
googlePlusPresenter.setView(this);
googlePlusPresenter.present();

}
public void showGooglePlus() {
googlePlus.setVisibility(VISIBLE);
}
public void hideGooglePlus() {
googlePlus.setVisibility(GONE);
}
}


The Presenter
public class GooglePlusPresenter {
private GooglePlayAvailability googlePlayAvailability;
private GooglePlusView googlePlusView;
public GooglePlusPresenter(GooglePlayAvailability availability) {
googlePlayAvailability = availability;
}

public void present() {
if (googlePlayAvailability.googlePlayIsAvailable()) {
googlePlusView.showGooglePlus();
} else {
googlePlusView.hideGooglePlus();
}
}
}


How to unit test?
@Mock GooglePlayAvailability googlePlayAvailability;
@Mock GooglePlusView googlePlus;
private GooglePlusPresenter presenter;
@Test
public void hidesGooglePlusIfNotAvailable() {
mockery.checking(new Expectations() {{
allowing(googlePlayAvailability).googlePlayIsAvailable();
will(returnValue(false));
oneOf(googlePlus).hideGooglePlus();
}});

presenter.present();
}


Device size diversity


How about Acceptance Tests?



public class ShazamTest extends
ActivityInstrumentationTestCase2<ActivityUnderTest> {
private static final int TIMEOUT = 5000;
private Solo solo;
protected void setUp() {
solo = new Solo(getInstrumentation());
}
}


public void testCanShazamOnPhone() {
// Action
// User hits the big Shazam button
View shazamButton = solo.getView(R.id.big_button);
solo.clickOnView(shazamButton);
// Assertions
// Track details are showing on full screen
assertThat(solo.waitForCondition(titleShowsOnFullScreen(),
TIMEOUT), is(true));
}


public void testShazamingOnTablet() {
// Action
// Hit small Shazam button and wait for animation to finish
final View shazamButton = solo.getView(R.id.small_button);
solo.clickOnView(shazamButton);
waitForAnimationToFinish();
// Assertions
// Track details are showing on side-panel
assertThat(solo.waitForCondition(titleShowsOnSidePanel(),

}


Test frameworks

GWEN

https://github.com/shazam/gwen


New Acceptance Test
protected void setUp() {
solo = new Solo(getInstrumentation());
user = new User(solo);
}
public void testCanShowTrackAfterShazaming() {
when(user).shazams();
then(user).seesDetailsForTrack();
}


User class
public class User implements Actor, Asserter {
private final Solo solo;
public void shazams() {
Action<Solo, Void> action;
if (isTablet()) {
action = new ShazamTabletButtonAction();
} else {
action = new ShazamPhoneButtonAction();
}
action.actOn(solo);
}
public void seesDetailsForTrack() {
Assertion<Solo> assertion;
if (isTablet()) {
assertion = new TabletDetailsAssertion();
} else {
assertion = new PhoneDetailsAssertion();
}
assertion.assertWith(solo);
}
}


Actions
public class ShazamPhoneButtonAction implements Action<Solo, Void> {
public void actOn(Solo solo) {
View bigButton = solo.getView(R.id.big_button);
solo.clickOnView(bigButton);
}
}
public class ShazamTabletButtonAction implements Action<Solo, Void> {
public void actOn(Solo solo) {
View smallButton = solo.getView(R.id.small_button);
solo.clickOnView(smallButton);
}
}


Assertions
public class PhoneDetailsAssertion implements Assertion<Solo>{
public void assertWith(Solo solo) {
assertThat(solo.waitForCondition(titleShowsOnFullScreen(),
}
}

public class TabletDetailsAssertion implements Assertion<Solo> {
public void assertWith(Solo solo) {
waitForAnimationToFinish();
assertThat(solo.waitForCondition(titleShowsOnSidePanel(),
}
}


Hiring...

Questions?
@iordanis_g
#fragVsCode
github.com/iordanis/androidCleanCode

Device fragmentation vs clean code

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