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Unit Testing in a Nutshell
Fumihiko Shiroyama
DroidKaigi 2018
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Who is this guy?
• Senior Android Developer @nikkei
• Executive Beer Drinker
• Chief Baby Sitter at home
• Unit Test Enthusiast
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Agenda today
• Why you should care about Unit Testing
• JUnit4 and basic assertions
• Mock and spy with Mockito
• Robolectric for framework's code
• Unit Testing SQLite
• Unit Testing asynchronous code
• Best practices and tips
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Why you should care about Unit Testing?
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What if you DON'T?
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public class LoginActivity extends AppCompatActivity implements LoaderCallbacks {
private static final int REQUEST_READ_CONTACTS = 0;
private static final String[] DUMMY_CREDENTIALS = new String[]{
"[email protected]:hello", "[email protected]:world"
};
private UserLoginTask mAuthTask = null;
private AutoCompleteTextView mEmailView;
private EditText mPasswordView;
private View mProgressView;
private View mLoginFormView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
mEmailView = (AutoCompleteTextView) findViewById(R.id.email);
populateAutoComplete();
mPasswordView = (EditText) findViewById(R.id.password);
mPasswordView.setOnEditorActionListener(new TextView.OnEditorActionListener() {
@Override
public boolean onEditorAction(TextView textView, int id, KeyEvent keyEvent) {
if (id == EditorInfo.IME_ACTION_DONE || id == EditorInfo.IME_NULL) {
attemptLogin();
return true;
}
return false;
}
});
Button mEmailSignInButton = (Button) findViewById(R.id.email_sign_in_button);
mEmailSignInButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View view) {
attemptLogin();
}
});
mLoginFormView = findViewById(R.id.login_form);
mProgressView = findViewById(R.id.login_progress);
}
private void populateAutoComplete() {
if (!mayRequestContacts()) {
return;
}
getLoaderManager().initLoader(0, null, this);
}
private boolean mayRequestContacts() {
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
return true;
}
if (checkSelfPermission(READ_CONTACTS) == PackageManager.PERMISSION_GRANTED) {
return true;
}
if (shouldShowRequestPermissionRationale(READ_CONTACTS)) {
Snackbar.make(mEmailView, R.string.permission_rationale, Snackbar.LENGTH_INDEFINITE)
.setAction(android.R.string.ok, new View.OnClickListener() {
@Override
@TargetApi(Build.VERSION_CODES.M)
public void onClick(View v) {
requestPermissions(new String[]{READ_CONTACTS}, REQUEST_READ_CONTACTS);
}
});
} else {
requestPermissions(new String[]{READ_CONTACTS}, REQUEST_READ_CONTACTS);
}
return false;
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
if (requestCode == REQUEST_READ_CONTACTS) {
if (grantResults.length == 1 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
populateAutoComplete();
}
}
}
private void attemptLogin() {
if (mAuthTask != null) {
return;
}
mEmailView.setError(null);
mPasswordView.setError(null);
String email = mEmailView.getText().toString();
String password = mPasswordView.getText().toString();
boolean cancel = false;
View focusView = null;
if (!TextUtils.isEmpty(password) && !isPasswordValid(password)) {
mPasswordView.setError(getString(R.string.error_invalid_password));
focusView = mPasswordView;
cancel = true;
}
if (TextUtils.isEmpty(email)) {
mEmailView.setError(getString(R.string.error_field_required));
focusView = mEmailView;
cancel = true;
} else if (!isEmailValid(email)) {
mEmailView.setError(getString(R.string.error_invalid_email));
focusView = mEmailView;
cancel = true;
}
if (cancel) {
focusView.requestFocus();
} else {
showProgress(true);
mAuthTask = new UserLoginTask(email, password);
mAuthTask.execute((Void) null);
}
}
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public class LoginActivity extends AppCompatActivity implements LoaderCallbacks {
private static final int REQUEST_READ_CONTACTS = 0;
private static final String[] DUMMY_CREDENTIALS = new String[]{
"[email protected]:hello", "[email protected]:world"
};
private UserLoginTask mAuthTask = null;
private AutoCompleteTextView mEmailView;
private EditText mPasswordView;
private View mProgressView;
private View mLoginFormView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
mEmailView = (AutoCompleteTextView) findViewById(R.id.email);
populateAutoComplete();
mPasswordView = (EditText) findViewById(R.id.password);
mPasswordView.setOnEditorActionListener(new TextView.OnEditorActionListener() {
@Override
public boolean onEditorAction(TextView textView, int id, KeyEvent keyEvent) {
if (id == EditorInfo.IME_ACTION_DONE || id == EditorInfo.IME_NULL) {
attemptLogin();
return true;
}
return false;
}
});
Button mEmailSignInButton = (Button) findViewById(R.id.email_sign_in_button);
mEmailSignInButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View view) {
attemptLogin();
}
});
mLoginFormView = findViewById(R.id.login_form);
mProgressView = findViewById(R.id.login_progress);
}
private void populateAutoComplete() {
if (!mayRequestContacts()) {
return;
}
getLoaderManager().initLoader(0, null, this);
}
private boolean mayRequestContacts() {
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
return true;
}
if (checkSelfPermission(READ_CONTACTS) == PackageManager.PERMISSION_GRANTED) {
return true;
}
if (shouldShowRequestPermissionRationale(READ_CONTACTS)) {
Snackbar.make(mEmailView, R.string.permission_rationale, Snackbar.LENGTH_INDEFINITE)
.setAction(android.R.string.ok, new View.OnClickListener() {
@Override
@TargetApi(Build.VERSION_CODES.M)
public void onClick(View v) {
requestPermissions(new String[]{READ_CONTACTS}, REQUEST_READ_CONTACTS);
}
});
} else {
requestPermissions(new String[]{READ_CONTACTS}, REQUEST_READ_CONTACTS);
}
return false;
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
if (requestCode == REQUEST_READ_CONTACTS) {
if (grantResults.length == 1 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
populateAutoComplete();
}
}
}
private void attemptLogin() {
if (mAuthTask != null) {
return;
}
mEmailView.setError(null);
mPasswordView.setError(null);
String email = mEmailView.getText().toString();
String password = mPasswordView.getText().toString();
boolean cancel = false;
View focusView = null;
if (!TextUtils.isEmpty(password) && !isPasswordValid(password)) {
mPasswordView.setError(getString(R.string.error_invalid_password));
focusView = mPasswordView;
cancel = true;
}
if (TextUtils.isEmpty(email)) {
mEmailView.setError(getString(R.string.error_field_required));
focusView = mEmailView;
cancel = true;
} else if (!isEmailValid(email)) {
mEmailView.setError(getString(R.string.error_invalid_email));
focusView = mEmailView;
cancel = true;
}
if (cancel) {
focusView.requestFocus();
} else {
showProgress(true);
mAuthTask = new UserLoginTask(email, password);
mAuthTask.execute((Void) null);
}
}
Faaaaaaaaaaaat Controller!!
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Fat Controller is bad because...
• Slow iteration
• Ambiguous responsibilities
• Off-by-one errors
• Un-reproducible bugs
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Unit testing lets you...
• Faster execution
• Clear division of roles
• Chance to improve architecture
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Is unit testing just enough?
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No!!
It just ensures it partially worked
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See also...
• EspressoςετίʔυͷಉظॲཧΛڀΊΔ
• Day1 Room5 15:40 -
• UIςετͷ࣮ߦ࣌ؒΛॖͤ͞Δํ๏
• Day2 Room2 18:30 -
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anyway
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JUnit4 and basic assertions
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JUnit4 is...
• A simple testing framework
• Available for Android out-of-the-box
• Still de-facto standard
Moving Forward with JUnit 5 - Day2 Room5 10:30 -
Check also
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Assertions
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Assertion is...
• Assert something is something
A rose is a rose is a rose is a rose...
assertThat(1 + 1).isEqualTo(2);
assertThat("Alice")
.isNotEmpty()
.isNotEqualTo("Bob");
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Installation
dependencies {
testImplementation 'junit:junit:4.12'
testImplementation 'com.squareup.assertj:assertj-android:1.2.0'
}
assertj-android lets you assert Android framework's code as well
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Test target
class InputChecker {
boolean isValid(String text) {
if (text.length() < 4) return false;
if (!text.matches("[a-zA-Z0-9]+")) return false;
return true;
}
}
VERY SIMPLE input text checker
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Create New Test
Command + SHIFT + T
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Create New Test
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Create New Test
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Types of test in Android
• Local Unit Tests
• Runs on JVM
• src/test
• Instrumented Tests
• Runs with Device/Emulators
• src/androidTest
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Local Unit Tests: pros
• Runs fast!
• No device, emulator, android sdk
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Local Unit Tests: cons
• No REAL Android framework's code
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• TRUE Android Test
• Exactly the same behavior as production
Instrumented Tests: pros
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Instrumented Tests: cons
• Runs slow!
• Need device, emulator, android sdk
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This session only cares
Local Unit Tests
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Test class
public class InputCheckerTest {
@Before
public void setUp() throws Exception {
}
@Test
public void isValid() throws Exception {
}
}
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Test class
public class InputCheckerTest {
@Before
public void setUp() throws Exception {
}
@Test
public void isValid() throws Exception {
}
}
Just naming convention
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Test class
public class InputCheckerTest {
@Before
public void setUp() throws Exception {
}
@Test
public void isValid() throws Exception {
}
}
Called at every test case
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Test class
public class InputCheckerTest {
@Before
public void setUp() throws Exception {
}
@Test
public void isValid() throws Exception {
}
}
This is a test case
Write as many as you want
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Test class
public class InputCheckerTest {
@Before
public void setUp() throws Exception {
}foo
@Test
public void isValid() throws Exception {
}foo
}foo
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Test class
public class InputCheckerTest {
private InputChecker inputChecker;
@Before
public void setUp() throws Exception {
inputChecker = new InputChecker();
}foo
@Test
public void isValid() throws Exception {
}foo
}foo
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Test class
public class InputCheckerTest {
private InputChecker inputChecker;
@Before
public void setUp() throws Exception {
inputChecker = new InputChecker();
}
@Test
public void isValid() throws Exception {
}
}
Initialization codes here
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Test class
public class InputCheckerTest {
private InputChecker inputChecker;
@Before
public void setUp() throws Exception {
inputChecker = new InputChecker();
}foo
@Test
public void isValid() throws Exception {
}foo
}foo
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Test class
public class InputCheckerTest {
private InputChecker inputChecker;
@Before
public void setUp() throws Exception {
inputChecker = new InputChecker();
}foo
@Test
public void isValid() throws Exception {
String input = "voodoo";
boolean actual = inputChecker.isValid(input);
Assertions.assertThat(actual).isTrue();
}foo
}foo
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Test class
public class InputCheckerTest {
private InputChecker inputChecker;
@Before
public void setUp() throws Exception {
inputChecker = new InputChecker();
}
@Test
public void isValid() throws Exception {
String input = "voodoo";
boolean actual = inputChecker.isValid(input);
Assertions.assertThat(actual).isTrue();
}
}
Write your assertions
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Test class
public class InputCheckerTest {
private InputChecker inputChecker;
@Before
public void setUp() throws Exception {
inputChecker = new InputChecker();
}
@Test
public void isValid() throws Exception {
String input = "voodoo";
boolean actual = inputChecker.isValid(input);
Assertions.assertThat(actual).isTrue();
}
}
what really is
"actual"
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Test class
public class InputCheckerTest {
private InputChecker inputChecker;
@Before
public void setUp() throws Exception {
inputChecker = new InputChecker();
}
@Test
public void isValid() throws Exception {
String input = "voodoo";
boolean actual = inputChecker.isValid(input);
Assertions.assertThat(actual).isTrue();
}
}
"expectation"
what you expect it to be
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Test class
public class InputCheckerTest {
private InputChecker inputChecker;
@Before
public void setUp() throws Exception {
inputChecker = new InputChecker();
}
@Test
public void isValid() throws Exception {
String input = "voodoo";
boolean actual = inputChecker.isValid(input);
Assertions.assertThat(actual).isTrue();
}
}
From AssertJ
Many assertion methods available
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Test class
public class InputCheckerTest {
private InputChecker inputChecker;
@Before
public void setUp() throws Exception {
inputChecker = new InputChecker();
}
@Test
public void isValid() throws Exception {
String input = "voodoo";
boolean actual = inputChecker.isValid(input);
Assertions.assertThat(actual).isTrue();
}
}
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Run tests
Run single
Run all
or
Passed!!!!
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If it fails...
reason why it failed
failure...
Fix and try again!!!
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Congrats!!!
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Assertions (AssertJ)
• assertThat(all)
• isEqualTo / isNotEqualTo
• assertThat(String)
• isEmpty / isNotEmpty
• assertThat(Number)
• isPositive / isNegative / isZero / isNotZero
• isGreaterThan / isLessThan
lots and lots and lots more
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• assertThat(list)
• contains / containsOnly / containsExactly
Assertions (AssertJ)
lots and lots and lots more
List strings = Arrays.asList("foo", "bar", "baz");
assertThat(strings).contains("bar");
same collection
same collection and order
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• http://joel-costigliola.github.io/assertj/
• https://github.com/square/assertj-android
• https://qiita.com/opengl-8080/items/
b07307ab0d33422be9c5
AssertJ
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Exceptions
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Remember this...
class InputChecker {
boolean isValid(String text) {
if (text.length() < 4) return false;
if (!text.matches("[a-zA-Z0-9]+")) return false;
return true;
}
}
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Remember this...
class InputChecker {
boolean isValid(String text) {
if (text.length() < 4) return false;
if (!text.matches("[a-zA-Z0-9]+")) return false;
return true;
}
}
What if null...
Let's try it anyway
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Ouch!!
@Test
public void isValid() throws Exception {
String input = null;
boolean actual = inputChecker.isValid(input);
assertThat(actual).isTrue();
}
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Expected Exception
@Test(expected = NullPointerException.class)
public void isValid() throws Exception {
String input = null;
boolean actual = inputChecker.isValid(input);
assertThat(actual).isTrue();
}
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Expected Exception
@Test(expected = NullPointerException.class)
public void isValid() throws Exception {
String input = null;
boolean actual = inputChecker.isValid(input);
assertThat(actual).isTrue();
}
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Passed!!
@Test(expected = NullPointerException.class)
public void isValid() throws Exception {
String input = null;
boolean actual = inputChecker.isValid(input);
assertThat(actual).isTrue();
}
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Better yet...
class InputChecker {
boolean isValid(String text) {
if (text.length() < 4) return false;
if (!text.matches("[a-zA-Z0-9]+")) return false;
return true;
}foo
}foo
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Better yet...
class InputChecker {
boolean isValid(@NonNull String text) {
if (text == null) throw new IllegalArgumentException("cannot be null");
if (text.length() < 4) return false;
if (!text.matches("[a-zA-Z0-9]+")) return false;
return true;
}foo
}foo
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Better yet...
class InputChecker {
boolean isValid(@NonNull String text) {
if (text == null) throw new IllegalArgumentException("cannot be null");
if (text.length() < 4) return false;
if (!text.matches("[a-zA-Z0-9]+")) return false;
return true;
}
}
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Better yet...
class InputChecker {
boolean isValid(@NonNull String text) {
if (text == null) throw new IllegalArgumentException("cannot be null");
if (text.length() < 4) return false;
if (!text.matches("[a-zA-Z0-9]+")) return false;
return true;
}
}
Unit testing helps you refactoring!!
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Way better!!
@Test(expected = IllegalArgumentException.class)
public void isValid() throws Exception {
String input = null;
boolean actual = inputChecker.isValid(input);
assertThat(actual).isTrue();
}
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Mock and spy with Mockito
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Mock is...
• A WHOLE imitation of a real object
• Used to simulate the behavior of
depending objects
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Spy is...
• A PARTIAL imitation of a real object
• Used to simulate the behavior of
depending objects
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Test Doubles
They are
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Why you need mocks?
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TweetRepository
public class TweetRepository {
private final LocalTweetDataSource localDataSource;
public TweetRepository(LocalTweetDataSource localDataSource) {
this.localDataSource = localDataSource;
}
public List getTimeline() {
return localDataSource.getTimeline();
}
}
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TweetRepository
public class TweetRepository {
private final LocalTweetDataSource localDataSource;
public TweetRepository(LocalTweetDataSource localDataSource) {
this.localDataSource = localDataSource;
}
public List getTimeline() {
return localDataSource.getTimeline();
}
}
depending on local data source
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Data Source
public class LocalTweetDataSource {
public List getTimeline() {
List tweets = new ArrayList<>();
// some local DB interaction
// .....
return tweets;
}
}
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Data Source
public class LocalTweetDataSource {
public List getTimeline() {
List tweets = new ArrayList<>();
// some local DB interaction
// .....
return tweets;
}
}
Because it dose so many interactions with DB
You don't wanna deal with all those messes!
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TweetRepository
public class TweetRepository {
private final LocalTweetDataSource localDataSource;
public TweetRepository(LocalTweetDataSource localDataSource) {
this.localDataSource = localDataSource;
}
public List getTimeline() {
return localDataSource.getTimeline();
}
}
You can replace this with simple mock
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Mockito
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Mockito is...
• A simple mocking library
• Most used one in Java and Android
community
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Installation
dependencies {
testImplementation 'org.mockito:mockito-inline:2.13.0'
}
mockito-inline lets you mock final class & methods
this artifact may be integrated into default in the future
but you can't mock
static methods & constructors
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Stubbing
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Stubbing
import static org.mockito.Mockito.*;
LocalTweetDataSource localDataSource = mock(LocalTweetDataSource.class);
when(localDataSource.getTimeline()).thenReturn(
Arrays.asList(
Tweet.bodyOf("foo"),
Tweet.bodyOf("bar"),
Tweet.bodyOf("baz")
)
);
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Stubbing
import static org.mockito.Mockito.*;
LocalTweetDataSource localDataSource = mock(LocalTweetDataSource.class);
when(localDataSource.getTimeline()).thenReturn(
Arrays.asList(
Tweet.bodyOf("foo"),
Tweet.bodyOf("bar"),
Tweet.bodyOf("baz")
)
);
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Stubbing
import static org.mockito.Mockito.*;
LocalTweetDataSource localDataSource = mock(LocalTweetDataSource.class);
when(localDataSource.getTimeline()).thenReturn(
Arrays.asList(
Tweet.bodyOf("foo"),
Tweet.bodyOf("bar"),
Tweet.bodyOf("baz")
)
);
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Stubbing
import static org.mockito.Mockito.*;
LocalTweetDataSource localDataSource = mock(LocalTweetDataSource.class);
when(localDataSource.getTimeline()).thenReturn(
Arrays.asList(
Tweet.bodyOf("foo"),
Tweet.bodyOf("bar"),
Tweet.bodyOf("baz")
)
);
mock instance
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Stubbing
import static org.mockito.Mockito.*;
LocalTweetDataSource localDataSource = mock(LocalTweetDataSource.class);
when(localDataSource.getTimeline()).thenReturn();
stub method
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Stubbing
import static org.mockito.Mockito.*;
LocalTweetDataSource localDataSource = mock(LocalTweetDataSource.class);
when(localDataSource.getTimeline()).thenReturn();
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Stubbing
import static org.mockito.Mockito.*;
LocalTweetDataSource localDataSource = mock(LocalTweetDataSource.class);
when(localDataSource.getTimeline()).thenReturn();
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Stubbing
import static org.mockito.Mockito.*;
LocalTweetDataSource localDataSource = mock(LocalTweetDataSource.class);
when(localDataSource.getTimeline()).thenReturn();
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Stubbing
import static org.mockito.Mockito.*;
LocalTweetDataSource localDataSource = mock(LocalTweetDataSource.class);
when(localDataSource.getTimeline()).thenReturn(
);zz
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Stubbing
import static org.mockito.Mockito.*;
LocalTweetDataSource localDataSource = mock(LocalTweetDataSource.class);
when(localDataSource.getTimeline()).thenReturn(
Arrays.asList(
Tweet.bodyOf("foo"),
Tweet.bodyOf("bar"),
Tweet.bodyOf("baz")
)
);zz
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Stubbing
import static org.mockito.Mockito.*;
LocalTweetDataSource localDataSource = mock(LocalTweetDataSource.class);
when(localDataSource.getTimeline()).thenReturn(
Arrays.asList(
Tweet.bodyOf("foo"),
Tweet.bodyOf("bar"),
Tweet.bodyOf("baz")
)
);zz
any item you wanna return
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Stubbing
import static org.mockito.Mockito.*;
LocalTweetDataSource localDataSource = mock(LocalTweetDataSource.class);
when(localDataSource.getTimeline()).thenReturn(
Arrays.asList(
Tweet.bodyOf("foo"),
Tweet.bodyOf("bar"),
Tweet.bodyOf("baz")
)
);
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Stubbing
private TweetRepository tweetRepository;
@Before
public void setUp() throws Exception {
LocalTweetDataSource localDataSource = mock(LocalTweetDataSource.class);
when(localDataSource.getTimeline()).thenReturn(
Arrays.asList(
Tweet.bodyOf("foo"),
Tweet.bodyOf("bar"),
Tweet.bodyOf("baz")
)
);
tweetRepository = new TweetRepository(localDataSource);
}
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Stubbing
private TweetRepository tweetRepository;
@Before
public void setUp() throws Exception {
LocalTweetDataSource localDataSource = mock(LocalTweetDataSource.class);
when(localDataSource.getTimeline()).thenReturn(
Arrays.asList(
Tweet.bodyOf("foo"),
Tweet.bodyOf("bar"),
Tweet.bodyOf("baz")
)
);
tweetRepository = new TweetRepository(localDataSource);
}
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Stubbing
@Test
public void getTimeline() throws Exception {
List tweets = tweetRepository.getTimeline();
assertThat(tweets)
.isNotEmpty()
.hasSize(3)
.containsExactly(
Tweet.bodyOf("foo"),
Tweet.bodyOf("bar"),
Tweet.bodyOf("baz")
);
}
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Stubbing
@Test
public void getTimeline() throws Exception {
List tweets = tweetRepository.getTimeline();
assertThat(tweets)
.isNotEmpty()
.hasSize(3)
.containsExactly(
Tweet.bodyOf("foo"),
Tweet.bodyOf("bar"),
Tweet.bodyOf("baz")
);
}
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Stubbing
@Test
public void getTimeline() throws Exception {
List tweets = tweetRepository.getTimeline();
assertThat(tweets)
.isNotEmpty()
.hasSize(3)
.containsExactly(
Tweet.bodyOf("foo"),
Tweet.bodyOf("bar"),
Tweet.bodyOf("baz")
);
}
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Stubbing
@Test
public void getTimeline() throws Exception {
List tweets = tweetRepository.getTimeline();
assertThat(tweets)
.isNotEmpty()
.hasSize(3)
.containsExactly(
Tweet.bodyOf("foo"),
Tweet.bodyOf("bar"),
Tweet.bodyOf("baz")
);
}
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Stubbing
@Test
public void getTimeline() throws Exception {
List tweets = tweetRepository.getTimeline();
assertThat(tweets)
.isNotEmpty()
.hasSize(3)
.containsExactly(
Tweet.bodyOf("foo"),
Tweet.bodyOf("bar"),
Tweet.bodyOf("baz")
);
}
pass!!
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Spying
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Spying is...
• Stub methods can be added on a REAL
object
That means spied objects acts EXACTLY the same
as real objects unless stubbed
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Spying
List strings = spy(new ArrayList());
strings.addAll(Arrays.asList("pop", "team", "epic"));
strings.forEach(System.out::println);
verify(strings, times(1)).addAll(
eq(Arrays.asList("pop", "team", "epic"))
);
verify(strings, never()).add(eq("pop"));
verify(strings, never()).get(anyInt());
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Spying
List strings = spy(new ArrayList());
strings.addAll(Arrays.asList("pop", "team", "epic"));
strings.forEach(System.out::println);
verify(strings, times(1)).addAll(
eq(Arrays.asList("pop", "team", "epic"))
);
verify(strings, never()).add(eq("pop"));
verify(strings, never()).get(anyInt());
normal ArrayList
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Spying
List strings = spy(new ArrayList());
strings.addAll(Arrays.asList("pop", "team", "epic"));
strings.forEach(System.out::println);
verify(strings, times(1)).addAll(
eq(Arrays.asList("pop", "team", "epic"))
);
verify(strings, never()).add(eq("pop"));
verify(strings, never()).get(anyInt());
wrap with spy()
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Spying
List strings = spy(new ArrayList());
strings.addAll(Arrays.asList("pop", "team", "epic"));
strings.forEach(System.out::println);
verify(strings, times(1)).addAll(
eq(Arrays.asList("pop", "team", "epic"))
);
verify(strings, never()).add(eq("pop"));
verify(strings, never()).get(anyInt());
things you typically to with List
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Verify
• Check the interactions with mock/spy
mocks/spies will remember all interactions
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Verify
List strings = spy(new ArrayList());
strings.addAll(Arrays.asList("pop", "team", "epic"));
strings.forEach(System.out::println);
verify(
);abc
verify(strings, never()).add(eq("pop"));
verify(strings, never()).get(anyInt());
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Verify
List strings = spy(new ArrayList());
strings.addAll(Arrays.asList("pop", "team", "epic"));
strings.forEach(System.out::println);
verify(strings, times(1)).addAll(
eq(Arrays.asList("pop", "team", "epic"))
);abc
verify(strings, never()).add(eq("pop"));
verify(strings, never()).get(anyInt());
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Verify
List strings = spy(new ArrayList());
strings.addAll(Arrays.asList("pop", "team", "epic"));
strings.forEach(System.out::println);
verify(strings, times(1)).addAll(
eq(Arrays.asList("pop", "team", "epic"))
);abc
verify(strings, never()).add(eq("pop"));
verify(strings, never()).get(anyInt());
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Verify
List strings = spy(new ArrayList());
strings.addAll(Arrays.asList("pop", "team", "epic"));
strings.forEach(System.out::println);
verify(strings, times(1)).addAll(
eq(Arrays.asList("pop", "team", "epic"))
);abc
verify(strings, never()).add(eq("pop"));
verify(strings, never()).get(anyInt());
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Verify
List strings = spy(new ArrayList());
strings.addAll(Arrays.asList("pop", "team", "epic"));
strings.forEach(System.out::println);
verify(strings, times(1)).addAll(
eq(Arrays.asList("pop", "team", "epic"))
);abc
verify(strings, never()).add(eq("pop"));
verify(strings, never()).get(anyInt());
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Verify
List strings = spy(new ArrayList());
strings.addAll(Arrays.asList("pop", "team", "epic"));
strings.forEach(System.out::println);
verify(strings, times(1)).addAll(
eq(Arrays.asList("pop", "team", "epic"))
);abc
verify(strings, never()).add(eq("pop"));
verify(strings, never()).get(anyInt());
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Verify
List strings = spy(new ArrayList());
strings.addAll(Arrays.asList("pop", "team", "epic"));
strings.forEach(System.out::println);
verify(strings, times(1)).addAll(
eq(Arrays.asList("pop", "team", "epic"))
);abc
verify(strings, never()).add(eq("pop"));
verify(strings, never()).get(anyInt());
notice!
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Verify
List strings = spy(new ArrayList());
strings.addAll(Arrays.asList("pop", "team", "epic"));
strings.forEach(System.out::println);
verify(strings, times(1)).addAll(
eq(Arrays.asList("pop", "team", "epic"))
);abc
verify(strings, never()).add(eq("pop"));
verify(strings, never()).get(anyInt());
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Verify
List strings = spy(new ArrayList());
strings.addAll(Arrays.asList("pop", "team", "epic"));
strings.forEach(System.out::println);
verify(strings, times(1)).addAll(
eq(Arrays.asList("pop", "team", "epic"))
);
verify(strings, never()).add(eq("pop"));
verify(strings, never()).get(anyInt());
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Verify
List strings = spy(new ArrayList());
strings.addAll(Arrays.asList("pop", "team", "epic"));
strings.forEach(System.out::println);
verify(strings, times(1)).addAll(
eq(Arrays.asList("pop", "team", "epic"))
);
verify(strings, never()).add(eq("pop"));
verify(strings, never()).get(anyInt());
no interaction
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Verify
List strings = spy(new ArrayList());
strings.addAll(Arrays.asList("pop", "team", "epic"));
strings.forEach(System.out::println);
verify(strings, times(1)).addAll(
eq(Arrays.asList("pop", "team", "epic"))
);
verify(strings, never()).add(eq("pop"));
verify(strings, never()).get(anyInt());
argument matcher
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Argument matchers
• eq(T)
• anyString()
• anyInt()
• any()
• any(Class)
• nullable(Class) null or T
including null
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Stubbing with callbacks
List strings = spy(new ArrayList());
String[] array = {"pop", "team", "epic"};
strings.addAll(asList(array));
when(strings.get(anyInt())).thenAnswer(invocation -> {
Object[] arguments = invocation.getArguments();
int index = (int) arguments[0];
if (index < array.length) return array[index];
return "something-else";
});
String got = strings.get(123);
assertThat(got).isEqualTo("something-else");
if you wanna change return val
according to the arguments
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Stubbing with callbacks
List strings = spy(new ArrayList());
String[] array = {"pop", "team", "epic"};
strings.addAll(asList(array));
when().thenAnswer(invocation -> {
});
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Stubbing with callbacks
List strings = spy(new ArrayList());
String[] array = {"pop", "team", "epic"};
strings.addAll(asList(array));
when(strings.get(anyInt())).thenAnswer(invocation -> {
Object[] arguments = invocation.getArguments();
int index = (int) arguments[0];
if (index < array.length) return array[index];
return "something-else";
});
String got = strings.get(123);
assertThat(got).isEqualTo("something-else");
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Stubbing with callbacks
List strings = spy(new ArrayList());
String[] array = {"pop", "team", "epic"};
strings.addAll(asList(array));
when(strings.get(anyInt())).thenAnswer(invocation -> {
Object[] arguments = invocation.getArguments();
int index = (int) arguments[0];
if (index < array.length) return array[index];
return "something-else";
});
String got = strings.get(123);
assertThat(got).isEqualTo("something-else");
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Stubbing with callbacks
List strings = spy(new ArrayList());
String[] array = {"pop", "team", "epic"};
strings.addAll(asList(array));
when(strings.get(anyInt())).thenAnswer(invocation -> {
Object[] arguments = invocation.getArguments();
int index = (int) arguments[0];
if (index < array.length) return array[index];
return "something-else";
});
String got = strings.get(123);
assertThat(got).isEqualTo("something-else");
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Stubbing with callbacks
List strings = spy(new ArrayList());
String[] array = {"pop", "team", "epic"};
strings.addAll(asList(array));
when(strings.get(anyInt())).thenAnswer(invocation -> {
Object[] arguments = invocation.getArguments();
int index = (int) arguments[0];
if (index < array.length) return array[index];
return "something-else";
});
String got = strings.get(123);
assertThat(got).isEqualTo("something-else");
whatever logic you like
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Stubbing with callbacks
List strings = spy(new ArrayList());
String[] array = {"pop", "team", "epic"};
strings.addAll(asList(array));
when(strings.get(anyInt())).thenAnswer(invocation -> {
Object[] arguments = invocation.getArguments();
int index = (int) arguments[0];
if (index < array.length) return array[index];
return "something-else";
});
String got = strings.get(123);
assertThat(got).isEqualTo("something-else");
Don't abuse this since it spoils simplicity
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Stubbing spy method
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doReturn
List strings = spy(new ArrayList());
strings.addAll(Arrays.asList("pop", "team", "epic"));
strings.forEach(System.out::println);
when(strings.get(3)).thenReturn("foo");
when().thenReturn() is almost always useful
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doReturn
List strings = spy(new ArrayList());
strings.addAll(Arrays.asList("pop", "team", "epic"));
strings.forEach(System.out::println);
when(strings.get(3)).thenReturn("foo");
0 1 2
Because this is a spy, not mock,
List#get() is evaluated first that causes an Exception
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doReturn
List strings = spy(new ArrayList());
strings.addAll(Arrays.asList("pop", "team", "epic"));
strings.forEach(System.out::println);
doReturn("foo").when(strings).get(3);
String got = strings.get(3);
Assertions.assertThat(got).isEqualTo("foo");
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doReturn
List strings = spy(new ArrayList());
strings.addAll(Arrays.asList("pop", "team", "epic"));
strings.forEach(System.out::println);
doReturn("foo").when(strings).get(3);
String got = strings.get(3);
Assertions.assertThat(got).isEqualTo("foo");
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doReturn
List strings = spy(new ArrayList());
strings.addAll(Arrays.asList("pop", "team", "epic"));
strings.forEach(System.out::println);
doReturn("foo").when(strings).get(3);
String got = strings.get(3);
Assertions.assertThat(got).isEqualTo("foo");
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doReturn
List strings = spy(new ArrayList());
strings.addAll(Arrays.asList("pop", "team", "epic"));
strings.forEach(System.out::println);
doReturn("foo").when(strings).get(3);
String got = strings.get(3);
Assertions.assertThat(got).isEqualTo("foo");
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doReturn
List strings = spy(new ArrayList());
strings.addAll(Arrays.asList("pop", "team", "epic"));
strings.forEach(System.out::println);
doReturn("foo").when(strings).get(3);
String got = strings.get(3);
Assertions.assertThat(got).isEqualTo("foo");
This works well!
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Stubbing void method
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doThrow / doNothing
List strings = spy(new ArrayList());
doThrow(new IllegalStateException()).when(strings).clear();
strings.clear();
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doThrow / doNothing
List strings = spy(new ArrayList());
doThrow(new IllegalStateException()).when(strings).clear();
strings.clear();
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doThrow / doNothing
List strings = spy(new ArrayList());
doThrow(new IllegalStateException()).when(strings).clear();
strings.clear();
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doThrow / doNothing
List strings = spy(new ArrayList());
doThrow(new IllegalStateException()).when(strings).clear();
strings.clear();
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doThrow / doNothing
List strings = spy(new ArrayList());
doThrow(new IllegalStateException()).when(strings).clear();
strings.clear();
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doThrow / doNothing
List strings = spy(new ArrayList());
doThrow(new IllegalStateException()).when(strings).clear();
strings.clear();
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doThrow / doNothing
List strings = spy(new ArrayList());
doThrow(new IllegalStateException()).when(strings).clear();
doNothing().when(strings).clear();
strings.clear();
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doThrow / doNothing
List strings = spy(new ArrayList());
doThrow(new IllegalStateException()).when(strings).clear();
doNothing().when(strings).clear();
strings.clear();
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doThrow / doNothing
List strings = spy(new ArrayList());
doThrow(new IllegalStateException()).when(strings).clear();
doNothing().when(strings).clear();
strings.clear(); pass!!
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• http://site.mockito.org/
• http://static.javadoc.io/org.mockito/mockito-core/
2.13.0/org/mockito/Mockito.html#0
Mockito
REALLY HELPFUL!!
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Robolectric for framework's code
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InputChecker
class InputChecker {
boolean isValid(@NonNull String text) {
if (text == null)
throw new IllegalArgumentException("cannot be null");
if (text.length() < 4) return false;
if (!text.matches("[a-zA-Z0-9]+")) return false;
return true;
}
}
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InputChecker
class InputChecker {
boolean isValid(@NonNull String text) {
if (TextUtils.isEmpty(text))
throw new IllegalArgumentException("cannot be blank");
if (text.length() < 4) return false;
if (!text.matches("[a-zA-Z0-9]+")) return false;
return true;
}
}
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InputChecker
class InputChecker {
boolean isValid(@NonNull String text) {
if (TextUtils.isEmpty(text))
throw new IllegalArgumentException("cannot be blank");
if (text.length() < 4) return false;
if (!text.matches("[a-zA-Z0-9]+")) return false;
return true;
}
}
android.text.TextUtils
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InputCheckerTest
public class InputCheckerTest {
private InputChecker inputChecker;
@Before
public void setUp() throws Exception {
inputChecker = new InputChecker();
}
@Test
public void isValid() throws Exception {
String input = "voodoo";
boolean actual = inputChecker.isValid(input);
assertThat(actual).isTrue();
}
}
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InputCheckerTest
Basically, Android framework's code cannot be executed
on JVM tests
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app/build.gradle
android {
testOptions {
unitTests.returnDefaultValues = true
}
} notice: this setting just return the default value
@Test isValid() passes successfully
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InputCheckerTest
public class InputCheckerTest {
private InputChecker inputChecker;
@Before
public void setUp() throws Exception {
inputChecker = new InputChecker();
}
@Test(expected = IllegalArgumentException.class)
public void isValid_fails_with_blank() throws Exception {
String input = "";
inputChecker.isValid(input);
}
} Add a test case that checks blank input
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InputCheckerTest
public class InputCheckerTest {
private InputChecker inputChecker;
@Before
public void setUp() throws Exception {
inputChecker = new InputChecker();
}
@Test(expected = IllegalArgumentException.class)
public void isValid_fails_with_blank() throws Exception {
String input = "";
inputChecker.isValid(input);
}
}
Expected exception was not thrown!
This is because of the "default value" from test options
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Robolectric
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Robolectric is...
• "A unit test framework that de-fangs the
Android SDK jar so you can test-drive the
development of your Android app."
• "Tests run inside the JVM on your
workstation in seconds."
quoted from the official site
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testImplementation "org.robolectric:robolectric:3.6.1"
android {
testOptions {
unitTests {
includeAndroidResources = true
}
}
}
Installation
remove: unitTests.returnDefaultValues = true
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InputCheckerTest
@RunWith(RobolectricTestRunner.class)
public class InputCheckerTest {
private InputChecker inputChecker;
@Before
public void setUp() throws Exception {
inputChecker = new InputChecker();
}
@Test(expected = IllegalArgumentException.class)
public void isValid_fails_with_blank() throws Exception {
String input = "";
inputChecker.isValid(input);
}
}
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InputCheckerTest
@RunWith(RobolectricTestRunner.class)
public class InputCheckerTest {
private InputChecker inputChecker;
@Before
public void setUp() throws Exception {
inputChecker = new InputChecker();
}
@Test(expected = IllegalArgumentException.class)
public void isValid_fails_with_blank() throws Exception {
String input = "";
inputChecker.isValid(input);
}
}
Just add this!!
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Context in Robolectric
@RunWith(RobolectricTestRunner.class)
public class SQLiteTest {
private SQLiteDatabase db;
@Before
public void setUp() throws Exception {
Context context
= RuntimeEnvironment.application.getApplicationContext();
SQLiteOpenHelper helper = new MySQLiteOpenHelper(context);
db = helper.getWritableDatabase();
}
@Test
public void test_db() throws Exception {
// do the stuff
}
}
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Context in Robolectric
@RunWith(RobolectricTestRunner.class)
public class SQLiteTest {
private SQLiteDatabase db;
@Before
public void setUp() throws Exception {
Context context
= RuntimeEnvironment.application.getApplicationContext();
SQLiteOpenHelper helper = new MySQLiteOpenHelper(context);
db = helper.getWritableDatabase();
}
@Test
public void test_db() throws Exception {
// do the stuff
}
}
Really handy to use!!
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• http://robolectric.org/
• http://robolectric.org/getting-started/
• http://robolectric.org/extending/
Robolectric
One thing you have to notice about Robolectric is
It just mimics the framework's behavior, not the real one
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Unit Testing SQLite
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• Robolectric simulates SQLite out-of-the-box!!
• You can use traditional SQLiteOpenHelper
• You can also use the latest Room Persistence Library
Unit Testing SQLite
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Room Persistence Library
dependencies {
implementation "android.arch.persistence.room:runtime:1.0.0"
annotationProcessor "android.arch.persistence.room:compiler:1.0.0"
}
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Room Persistence Library
@Entity
public class User {
@PrimaryKey
private int uid;
@ColumnInfo(name = "first_name")
private String firstName;
@ColumnInfo(name = "last_name")
private String lastName;
public User(String firstName, String lastName) {
this.firstName = firstName;
this.lastName = lastName;
}
// getters & setters
}
Entity
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Room Persistence Library
@Dao
public interface UserDao {
@Query("SELECT * FROM user")
List getAll();
@Query("SELECT * FROM user WHERE uid IN (:userIds)")
List loadAllByIds(int[] userIds);
@Query("SELECT * FROM user WHERE first_name LIKE :first AND "
+ "last_name LIKE :last LIMIT 1")
User findByName(String first, String last);
@Insert
void insertAll(User... users);
@Delete
void delete(User user);
}
Dao
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Room Persistence Library
@Database(entities = {User.class}, version = 1)
public abstract class AppDatabase extends RoomDatabase {
public abstract UserDao userDao();
}
Database
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Room Persistence Library
public class UserManager {
private final String DB_NAME = "sample_app";
private final AppDatabase db;
public UserManager(@NonNull Context context) {
db = Room.databaseBuilder(context.getApplicationContext(),
AppDatabase.class, DB_NAME)
.allowMainThreadQueries()
.build();
}
public void insertUser(@NonNull User user) {
db.userDao().insertAll(user);
}
public List getUsers() {
return db.userDao().getAll();
}
}
Business Logic
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Room Persistence Library
public class UserManager {
private final String DB_NAME = "sample_app";
private final AppDatabase db;
public UserManager(@NonNull Context context) {
db = Room.databaseBuilder(context.getApplicationContext(),
AppDatabase.class, DB_NAME)
.allowMainThreadQueries()
.build();
}
public void insertUser(@NonNull User user) {
db.userDao().insertAll(user);
}
public List getUsers() {
return db.userDao().getAll();
}
}
Business Logic
just for demo's convenience
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Room Persistence Library
public class UserManager {
private final String DB_NAME = "sample_app";
private final AppDatabase db;
public UserManager(@NonNull Context context) {
db = Room.databaseBuilder(context.getApplicationContext(),
AppDatabase.class, DB_NAME)
.allowMainThreadQueries()
.build();
}
public void insertUser(@NonNull User user) {
db.userDao().insertAll(user);
}
public List getUsers() {
return db.userDao().getAll();
}
}
Business Logic
delegate
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Room Persistence Library
public class UserManager {
private final String DB_NAME = "sample_app";
private final AppDatabase db;
public UserManager(@NonNull Context context) {
db = Room.databaseBuilder(context.getApplicationContext(),
AppDatabase.class, DB_NAME)
.allowMainThreadQueries()
.build();
}
public void insertUser(@NonNull User user) {
db.userDao().insertAll(user);
}
public List getUsers() {
return db.userDao().getAll();
}
}
Business Logic
delegate
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Room Persistence Library
@RunWith(RobolectricTestRunner.class)
public class UserManagerTest {
private UserManager userManager;
@Before
public void setUp() throws Exception {
Context context
= RuntimeEnvironment.application.getApplicationContext();
userManager = new UserManager(context);
}
@Test
public void insert_and_get() throws Exception {
List users = userManager.getUsers();
assertThat(users).isEmpty();
userManager.insertUser(new User("Fumihiko", "Shiroyama"));
users = userManager.getUsers();
assertThat(users)
.isNotEmpty()
.hasSize(1);
}
}
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Room Persistence Library
@RunWith(RobolectricTestRunner.class)
public class UserManagerTest {
private UserManager userManager;
@Before
public void setUp() throws Exception {
Context context
= RuntimeEnvironment.application.getApplicationContext();
userManager = new UserManager(context);
}
@Test
public void insert_and_get() throws Exception {
List users = userManager.getUsers();
assertThat(users).isEmpty();
userManager.insertUser(new User("Fumihiko", "Shiroyama"));
users = userManager.getUsers();
assertThat(users)
.isNotEmpty()
.hasSize(1);
}
}
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Room Persistence Library
@RunWith(RobolectricTestRunner.class)
public class UserManagerTest {
private UserManager userManager;
@Before
public void setUp() throws Exception {
Context context
= RuntimeEnvironment.application.getApplicationContext();
userManager = new UserManager(context);
}
@Test
public void insert_and_get() throws Exception {
List users = userManager.getUsers();
assertThat(users).isEmpty();
userManager.insertUser(new User("Fumihiko", "Shiroyama"));
users = userManager.getUsers();
assertThat(users)
.isNotEmpty()
.hasSize(1);
}
}
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Room Persistence Library
@RunWith(RobolectricTestRunner.class)
public class UserManagerTest {
private UserManager userManager;
@Before
public void setUp() throws Exception {
Context context
= RuntimeEnvironment.application.getApplicationContext();
userManager = new UserManager(context);
}
@Test
public void insert_and_get() throws Exception {
List users = userManager.getUsers();
assertThat(users).isEmpty();
userManager.insertUser(new User("Fumihiko", "Shiroyama"));
users = userManager.getUsers();
assertThat(users)
.isNotEmpty()
.hasSize(1);
}
}
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Room Persistence Library
@RunWith(RobolectricTestRunner.class)
public class UserManagerTest {
private UserManager userManager;
@Before
public void setUp() throws Exception {
Context context
= RuntimeEnvironment.application.getApplicationContext();
userManager = new UserManager(context);
}
@Test
public void insert_and_get() throws Exception {
List users = userManager.getUsers();
assertThat(users).isEmpty();
userManager.insertUser(new User("Fumihiko", "Shiroyama"));
users = userManager.getUsers();
assertThat(users)
.isNotEmpty()
.hasSize(1);
}
}
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Room Persistence Library
@RunWith(RobolectricTestRunner.class)
public class UserManagerTest {
private UserManager userManager;
@Before
public void setUp() throws Exception {
Context context
= RuntimeEnvironment.application.getApplicationContext();
userManager = new UserManager(context);
}
@Test
public void insert_and_get() throws Exception {
List users = userManager.getUsers();
assertThat(users).isEmpty();
userManager.insertUser(new User("Fumihiko", "Shiroyama"));
users = userManager.getUsers();
assertThat(users)
.isNotEmpty()
.hasSize(1);
}
}
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Room Persistence Library
@RunWith(RobolectricTestRunner.class)
public class UserManagerTest {
private UserManager userManager;
@Before
public void setUp() throws Exception {
Context context
= RuntimeEnvironment.application.getApplicationContext();
userManager = new UserManager(context);
}
@Test
public void insert_and_get() throws Exception {
List users = userManager.getUsers();
assertThat(users).isEmpty();
userManager.insertUser(new User("Fumihiko", "Shiroyama"));
users = userManager.getUsers();
assertThat(users)
.isNotEmpty()
.hasSize(1);
}
}
DB & table's data are reset automatically
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Room Persistence Library
• https://developer.android.com/topic/
libraries/architecture/room.html
• https://developer.android.com/topic/
libraries/architecture/adding-
components.html
• https://developer.android.com/training/
data-storage/room/index.html
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Unit Testing asynchronous code
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Testing async code
• Testing asynchronous code is not always
easy
I'd introduce the very basic concept of it!
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Synchronous call
interface Fetcher {
T fetch();
class StringFetcher implements Fetcher {
@Override
public String fetch() {
return "OK";
}
}
} Think of a synchronous API call over internet
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Simple callback
Callback interfaces
interface OnSuccess {
void onSuccess(T result);
}
interface OnFailure {
void onFailure(Exception e);
}
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Asynchronous call
class AsyncFetcher {
private final Fetcher fetcher;
AsyncFetcher(Fetcher fetcher) {
this.fetcher = fetcher;
}
void fetch(OnSuccess onSuccess, OnFailure onFailure) {
new Thread(() -> {
try {
Thread.sleep(1000L);
onSuccess.onSuccess(fetcher.fetch());
} catch (Exception e) {
onFailure.onFailure(e);
}
}).start();
}
}
Think of an asynchronous API call over internet
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Asynchronous call
class AsyncFetcher {
private final Fetcher fetcher;
AsyncFetcher(Fetcher fetcher) {
this.fetcher = fetcher;
}
void fetch(OnSuccess onSuccess, OnFailure onFailure) {
new Thread(() -> {
try {
Thread.sleep(1000L);
onSuccess.onSuccess(fetcher.fetch());
} catch (Exception e) {
onFailure.onFailure(e);
}
}).start();
}
}
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Asynchronous call
class AsyncFetcher {
private final Fetcher fetcher;
AsyncFetcher(Fetcher fetcher) {
this.fetcher = fetcher;
}
void fetch(OnSuccess onSuccess, OnFailure onFailure) {
new Thread(() -> {
try {
Thread.sleep(1000L);
onSuccess.onSuccess(fetcher.fetch());
} catch (Exception e) {
onFailure.onFailure(e);
}
}).start();
}
}
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Asynchronous call
class AsyncFetcher {
private final Fetcher fetcher;
AsyncFetcher(Fetcher fetcher) {
this.fetcher = fetcher;
}
void fetch(OnSuccess onSuccess, OnFailure onFailure) {
new Thread(() -> {
try {
Thread.sleep(1000L);
onSuccess.onSuccess(fetcher.fetch());
} catch (Exception e) {
onFailure.onFailure(e);
}
}).start();
}
}
Executed on a different thread
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Asynchronous call
class AsyncFetcher {
private final Fetcher fetcher;
AsyncFetcher(Fetcher fetcher) {
this.fetcher = fetcher;
}
void fetch(OnSuccess onSuccess, OnFailure onFailure) {
new Thread(() -> {
try {
Thread.sleep(1000L);
onSuccess.onSuccess(fetcher.fetch());
} catch (Exception e) {
onFailure.onFailure(e);
}
}).start();
}
}
time intensive task
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Asynchronous call
class AsyncFetcher {
private final Fetcher fetcher;
AsyncFetcher(Fetcher fetcher) {
this.fetcher = fetcher;
}
void fetch(OnSuccess onSuccess, OnFailure onFailure) {
new Thread(() -> {
try {
Thread.sleep(1000L);
onSuccess.onSuccess(fetcher.fetch());
} catch (Exception e) {
onFailure.onFailure(e);
}
}).start();
}
}
Callbacks
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Asynchronous Test
public class AsyncFetcherTest {
private Fetcher fetcher;
private AsyncFetcher asyncFetcher;
@Before
public void setUp() throws Exception {
fetcher = spy(new Fetcher.StringFetcher());
asyncFetcher = new AsyncFetcher<>(fetcher);
}
@Test
public void fetch_success() throws Exception {
asyncFetcher.fetch();
}
}
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Asynchronous Test
public class AsyncFetcherTest {
private Fetcher fetcher;
private AsyncFetcher asyncFetcher;
@Before
public void setUp() throws Exception {
fetcher = spy(new Fetcher.StringFetcher());
asyncFetcher = new AsyncFetcher<>(fetcher);
}
@Test
public void fetch_success() throws Exception {
asyncFetcher.fetch();
}
}
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Asynchronous Test
public class AsyncFetcherTest {
private Fetcher fetcher;
private AsyncFetcher asyncFetcher;
@Before
public void setUp() throws Exception {
fetcher = spy(new Fetcher.StringFetcher());
asyncFetcher = new AsyncFetcher<>(fetcher);
}
@Test
public void fetch_success() throws Exception {
asyncFetcher.fetch();
}
}
How do I write this test?
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Asynchronous Test
@Test
public void fetch_success() throws Exception {
asyncFetcher.fetch(
result -> {
assertThat(result).isEqualTo("OK");
log("async: ok");
},
e -> log("async: ng")
);
log("fetch_success: end");
}
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Asynchronous Test
@Test
public void fetch_success() throws Exception {
asyncFetcher.fetch(
result -> {
assertThat(result).isEqualTo("OK");
log("async: ok");
},
e -> log("async: ng")
);
log("fetch_success: end");
}
success
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Asynchronous Test
@Test
public void fetch_success() throws Exception {
asyncFetcher.fetch(
result -> {
assertThat(result).isEqualTo("OK");
log("async: ok");
},
e -> log("async: ng")
);
log("fetch_success: end");
}
failure
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Asynchronous Test
@Test
public void fetch_failure() throws Exception {
doThrow(new RuntimeException("NG")).when(fetcher).fetch();
asyncFetcher.fetch(
result -> log("async: ok"),
e -> {
assertThat(e.getMessage()).isEqualTo("NG");
log("async: ng");
}
);
log("fetch_failure: end");
}
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Asynchronous Test
@Test
public void fetch_failure() throws Exception {
doThrow(new RuntimeException("NG")).when(fetcher).fetch();
asyncFetcher.fetch(
result -> log("async: ok"),
e -> {
assertThat(e.getMessage()).isEqualTo("NG");
log("async: ng");
}
);
log("fetch_failure: end");
}
stub failure
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Asynchronous Test
Callback is NOT actually called!!!
Execution seems successful...but wait?
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Asynchronous Test
private CountDownLatch latch;
@Before
public void setUp() throws Exception {
fetcher = spy(new Fetcher.StringFetcher());
asyncFetcher = new AsyncFetcher<>(fetcher);
latch = new CountDownLatch(1);
}
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Asynchronous Test
Acts like an ON/OFF latch
private CountDownLatch latch;
@Before
public void setUp() throws Exception {
fetcher = spy(new Fetcher.StringFetcher());
asyncFetcher = new AsyncFetcher<>(fetcher);
latch = new CountDownLatch(1);
}
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Asynchronous Test
@Test
public void fetch_success() throws Exception {
asyncFetcher.fetch(
result -> {
assertThat(result).isEqualTo("OK");
log("async: ok");
latch.countDown();
},
e -> log("async: ng")
);
latch.await();
log("fetch_success: end");
}
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Asynchronous Test
@Test
public void fetch_success() throws Exception {
asyncFetcher.fetch(
result -> {
assertThat(result).isEqualTo("OK");
log("async: ok");
latch.countDown();
},
e -> log("async: ng")
);
latch.await();
log("fetch_success: end");
}
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Asynchronous Test
@Test
public void fetch_success() throws Exception {
asyncFetcher.fetch(
result -> {
assertThat(result).isEqualTo("OK");
log("async: ok");
latch.countDown();
},
e -> log("async: ng")
);
latch.await();
log("fetch_success: end");
}
Test execution awaits here
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Asynchronous Test
@Test
public void fetch_success() throws Exception {
asyncFetcher.fetch(
result -> {
assertThat(result).isEqualTo("OK");
log("async: ok");
latch.countDown();
},
e -> log("async: ng")
);
latch.await();
log("fetch_success: end");
}
Opens the latch and test goes again
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Asynchronous Test
@Test
public void fetch_failure() throws Exception {
doThrow(new RuntimeException("NG")).when(fetcher).fetch();
asyncFetcher.fetch(
result -> log("async: ok"),
e -> {
assertThat(e.getMessage()).isEqualTo("NG");
log("async: ng");
latch.countDown();
}
);
latch.await();
log("fetch_failure: end");
}
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Asynchronous Test
@Test
public void fetch_failure() throws Exception {
doThrow(new RuntimeException("NG")).when(fetcher).fetch();
asyncFetcher.fetch(
result -> log("async: ok"),
e -> {
assertThat(e.getMessage()).isEqualTo("NG");
log("async: ng");
latch.countDown();
}
);
latch.await();
log("fetch_failure: end");
}
The same implementation as success
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Asynchronous Test
Callback is properly called!!!
Log message seems correct!!
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Additional info...
• MockWebServer for OkHttp
• TestSubscriber for RxJava
• https://speakerdeck.com/srym/
hayaiyasuiumai-sutatoatupudemoshi-eru-
retrofit-plus-rxjava-deshun-jian-
apikutukinguresipi?slide=17
Check this slide & sample project
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Best practices and tips
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Best practices and tips
• Use interface at the structural boundary
• Use DI pattern for testability
• Static is EVIL
• Don't be a Mad Tester
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Use interface
at the structural boundary
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Repository pattern
public class TweetRepository {
private final LocalTweetDataSource localDataSource;
public TweetRepository(LocalTweetDataSource localDataSource) {
this.localDataSource = localDataSource;
}
public List getTimeline() {
return localDataSource.getTimeline();
}
}
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Repository pattern
public class LocalTweetDataSource {
public List getTimeline() {
List tweets = new ArrayList<>();
// some local DB interaction
return tweets;
}
}
Concrete data source
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Repository pattern
public interface LocalTweetDataSource {
List getTimeline();
class SQLiteTweetDataSource implements LocalTweetDataSource {
@Override
public List getTimeline() {
List tweets = new ArrayList<>();
// some local DB interaction
return tweets;
}
}
class MockTweetDataSource implements LocalTweetDataSource {
@Override
public List getTimeline() {
return Arrays.asList(/* some mock data */);
}
}
}
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Repository pattern
public interface LocalTweetDataSource {
List getTimeline();
class SQLiteTweetDataSource implements LocalTweetDataSource {
@Override
public List getTimeline() {
List tweets = new ArrayList<>();
// some local DB interaction
return tweets;
}
}
class MockTweetDataSource implements LocalTweetDataSource {
@Override
public List getTimeline() {
return Arrays.asList(/* some mock data */);
}
}
}
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Repository pattern
public interface LocalTweetDataSource {
List getTimeline();
class SQLiteTweetDataSource implements LocalTweetDataSource {
@Override
public List getTimeline() {
List tweets = new ArrayList<>();
// some local DB interaction
return tweets;
}
}
class MockTweetDataSource implements LocalTweetDataSource {
@Override
public List getTimeline() {
return Arrays.asList(/* some mock data */);
}
}
}
Concrete data source with real DB interactions
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Repository pattern
public interface LocalTweetDataSource {
List getTimeline();
class SQLiteTweetDataSource implements LocalTweetDataSource {
@Override
public List getTimeline() {
List tweets = new ArrayList<>();
// some local DB interaction
return tweets;
}
}
class MockTweetDataSource implements LocalTweetDataSource {
@Override
public List getTimeline() {
return Arrays.asList(/* some mock data */);
}
}
}
mock data source just for tests
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Repository pattern
public class TweetRepositoryTest {
private TweetRepository tweetRepository;
@Before
public void setUp() throws Exception {
LocalTweetDataSource localDataSource = mock(LocalTweetDataSource.class);
when(localDataSource.getTimeline()).thenReturn(
Arrays.asList(
Tweet.bodyOf("foo"),
Tweet.bodyOf("bar"),
Tweet.bodyOf("baz")));
tweetRepository = new TweetRepository(localDataSource);
}
}
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Repository pattern
public class TweetRepositoryTest {
private TweetRepository tweetRepository;
@Before
public void setUp() throws Exception {
LocalTweetDataSource localDataSource
= new LocalTweetDataSource.MockTweetDataSource();
tweetRepository = new TweetRepository(localDataSource);
}
} You can even get rid of Mockito dependency
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Use DI pattern for testability
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Use DI pattern
public class TweetRepository {
private final LocalTweetDataSource localDataSource;
public TweetRepository() {
this.localDataSource = new LocalTweetDataSource.SQLiteTweetDataSource();
}
public List getTimeline() {
return localDataSource.getTimeline();
}
}
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Use DI pattern
public class TweetRepository {
private final LocalTweetDataSource localDataSource;
public TweetRepository() {
this.localDataSource = new LocalTweetDataSource.SQLiteTweetDataSource();
}
public List getTimeline() {
return localDataSource.getTimeline();
}
}
mocking field is painful!!
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Use DI pattern
public class TweetRepository {
private final LocalTweetDataSource localDataSource;
public TweetRepository() {
this.localDataSource = new LocalTweetDataSource.SQLiteTweetDataSource();
}
public List getTimeline() {
return localDataSource.getTimeline();
}
}
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Use DI pattern
public class TweetRepository {
private final LocalTweetDataSource localDataSource;
public TweetRepository(LocalTweetDataSource localDataSource) {
this.localDataSource = localDataSource;
}
public List getTimeline() {
return localDataSource.getTimeline();
}
}
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Use DI pattern
public class TweetRepository {
private final LocalTweetDataSource localDataSource;
public TweetRepository(LocalTweetDataSource localDataSource) {
this.localDataSource = localDataSource;
}
public List getTimeline() {
return localDataSource.getTimeline();
}
}
Putting dependency from outer
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Use DI pattern
• This is so-called DI pattern
• DI pattern does NOT have to use DI library
• DI library (e.g. Dagger2) is useful though
e.g. Factory Pattern
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Static is EVIL
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Static is EVIL because...
• Static has global scope
• Mockito cannot mock static
• Static is practically unnecessary
This may cause order dependent bugs
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Static is practically unnecessary
@Singleton
public class TweetRepository {
private final LocalTweetDataSource localDataSource;
@Inject
public TweetRepository(LocalTweetDataSource localDataSource) {
this.localDataSource = localDataSource;
}
public List getTimeline() {
return localDataSource.getTimeline();
}
}
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Static is practically unnecessary
@Singleton
public class TweetRepository {
private final LocalTweetDataSource localDataSource;
@Inject
public TweetRepository(LocalTweetDataSource localDataSource) {
this.localDataSource = localDataSource;
}
public List getTimeline() {
return localDataSource.getTimeline();
}
}
Use Dagger's annotations for handy singleton
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Don't be a Mad Tester
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Don't be a Mad Tester
• Avoid to test EVERYTHING
• Unit tests are NOT perfect
• Gain maximum with minimum investment!
Enjoy your test life!!!
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Thank you for listening!
• All illustrations by www.irasutoya.com
• Special Thanks to @sumio_tym, @numa08
• Get the slides: https://goo.gl/ju66No
• Get the materials: https://goo.gl/R5kBeN