1. Unit tests
Landon Cox
April 25, 2017

2. Things covered this semester
Design patterns (code structure)
Decorator
Open/close principle
APIs (external libraries, services)
Firebase
SQLite
Volley
Project management tools
Android studio
git
What’s missing?

3. Topics this semester Design patterns (code structure)
Decorator
Open/close principle
APIs (external libraries, services)
Firebase
SQLite
Volley
Project management tools
Android studio
git
What’s missing? Testing!

4. Unit testing Unit tests are small Run tests at build time
Exercise a single method or class
Test behavior in isolation from rest of program
Run tests at build time
Should be integrated into gradle
Sanity check any changes you make
Fail a unit test? Fail the build.

5. Unit testing in Android
Local unit tests
Run locally on your machine
Cannot depend on a launched app
Instrumented unit tests
Run on an emulator or device
Have access to Context object

6. Unit testing in Android
Local unit tests
Run locally on your machine
Cannot depend on a launched app
Instrumented unit tests
Run on an emulator or device
Have access to Context object

7. Example local test
import org.junit.Test; import java.util.regex.Pattern; import static org.junit.Assert.assertFalse; import static org.junit.Assert.assertTrue; public class ValidatorTest {       public void Validator_Correct Simple_ReturnsTrue() {         is(true));     } }

8. Import stuff from org.junit.*
Example local test
Import stuff from org.junit.*
import org.junit.Test; import java.util.regex.Pattern; import static org.junit.Assert.assertFalse; import static org.junit.Assert.assertTrue; public class ValidatorTest {       public void Validator_Correct Simple_ReturnsTrue() {         is(true));     } }

9. Annotate method w/ @Test
Example local test
Annotate method
import org.junit.Test; import java.util.regex.Pattern; import static org.junit.Assert.assertFalse; import static org.junit.Assert.assertTrue; public class ValidatorTest {       public void Validator_Correct Simple_ReturnsTrue() {         is(true));     } }

10. Use assertions in test method
Example local test
Use assertions in test method
import org.junit.Test; import java.util.regex.Pattern; import static org.junit.Assert.assertFalse; import static org.junit.Assert.assertTrue; public class ValidatorTest {       public void Validator_Correct Simple_ReturnsTrue() {         is(true));     } }

11. Use assertions in test method
Example local test
Use assertions in test method
import org.junit.Test; import java.util.regex.Pattern; import static org.junit.Assert.assertFalse; import static org.junit.Assert.assertTrue; public class ValidatorTest {       public void Validator_Correct Simple_ReturnsTrue() {         is(true));     } }

12. Example local test
import org.junit.Test; import java.util.regex.Pattern; import static org.junit.Assert.assertFalse; import static org.junit.Assert.assertTrue; public class ValidatorTest {       public void Validator_Correct Simple_ReturnsTrue() {         is(true));     } }
These tests are useful for simple, stateless methods, like code that checks valid s.

13. Tests are also pretty limited …
Example local test
import org.junit.Test; import java.util.regex.Pattern; import static org.junit.Assert.assertFalse; import static org.junit.Assert.assertTrue; public class ValidatorTest {       public void Validator_Correct Simple_ReturnsTrue() {         is(true));     } }
Tests are also pretty limited …

14. Unit testing in Android
Local unit tests
Run locally on your machine
Cannot depend on a launched app
Instrumented unit tests
Run on an emulator or device
Have access to Context object

15. Example instrumented test
import static org.hamcrest.MatcherAssert.assertThat; import static org.hamcrest.CoreMatchers.*; import static org.mockito.Mockito.*; import org.junit.Test; import org.junit.runner.RunWith; import org.mockito.Mock; import org.mockito.runners.MockitoJUnitRunner; import android.content.SharedPreferences; @RunWith(MockitoJUnitRunner.class) public class UnitTestSample {     private static final String FAKE_STRING = "HELLO WORLD";       Context mMockContext;       public void readStringFromContext_LocalizedString() {
…     } }
Import stuff from org.junit.*

16. Example instrumented test
import static org.hamcrest.MatcherAssert.assertThat; import static org.hamcrest.CoreMatchers.*; import static org.mockito.Mockito.*; import org.junit.Test; import org.junit.runner.RunWith; import org.mockito.Mock; import org.mockito.runners.MockitoJUnitRunner; import android.content.SharedPreferences; @RunWith(MockitoJUnitRunner.class) public class UnitTestSample {     private static final String FAKE_STRING = "HELLO WORLD";       Context mMockContext;       public void readStringFromContext_LocalizedString() {
…     } }
Import stuff from org.mockito.*

17. Example instrumented test
import static org.hamcrest.MatcherAssert.assertThat; import static org.hamcrest.CoreMatchers.*; import static org.mockito.Mockito.*; import org.junit.Test; import org.junit.runner.RunWith; import org.mockito.Mock; import org.mockito.runners.MockitoJUnitRunner; import android.content.SharedPreferences; @RunWith(MockitoJUnitRunner.class) public class UnitTestSample {     private static final String FAKE_STRING = "HELLO WORLD";       Context mMockContext;       public void readStringFromContext_LocalizedString() {
…     } }
Import stuff from org.hamcrest.*

18. Example instrumented test
import static org.hamcrest.MatcherAssert.assertThat; import static org.hamcrest.CoreMatchers.*; import static org.mockito.Mockito.*; import org.junit.Test; import org.junit.runner.RunWith; import org.mockito.Mock; import org.mockito.runners.MockitoJUnitRunner; import android.content.SharedPreferences; @RunWith(MockitoJUnitRunner.class) public class UnitTestSample {     private static final String FAKE_STRING = "HELLO WORLD";       Context mMockContext;       public void readStringFromContext_LocalizedString() {
…     } }
Annotate class

19. Example instrumented test
import static org.hamcrest.MatcherAssert.assertThat; import static org.hamcrest.CoreMatchers.*; import static org.mockito.Mockito.*; import org.junit.Test; import org.junit.runner.RunWith; import org.mockito.Mock; import org.mockito.runners.MockitoJUnitRunner; import android.content.SharedPreferences; @RunWith(MockitoJUnitRunner.class) public class UnitTestSample {     private static final String FAKE_STRING = "HELLO WORLD";       Context mMockContext;       public void readStringFromContext_LocalizedString() {
…     } }
Annotate mock objects

20. Example instrumented test
import static org.hamcrest.MatcherAssert.assertThat; import static org.hamcrest.CoreMatchers.*; import static org.mockito.Mockito.*; import org.junit.Test; import org.junit.runner.RunWith; import org.mockito.Mock; import org.mockito.runners.MockitoJUnitRunner; import android.content.SharedPreferences; @RunWith(MockitoJUnitRunner.class) public class UnitTestSample {     private static final String FAKE_STRING = "HELLO WORLD";       Context mMockContext;       public void readStringFromContext_LocalizedString() {
…     } }
Annotate test methods

21. Example instrumented test
… import android.content.SharedPreferences; @RunWith(MockitoJUnitRunner.class) public class UnitTestSample {     private static final String FAKE_STRING = "HELLO WORLD";       Context mMockContext;       public void readStringFromContext_LocalizedString() {
        // Given a mocked Context injected into the object under test...         when(mMockContext.getString(R.string.hello_word))                 .thenReturn(FAKE_STRING);         ClassUnderTest myObjectUnderTest = new ClassUnderTest(mMockContext);         // ...when the string is returned from the object under test...         String result = myObjectUnderTest.getHelloWorldString();         // ...then the result should be the expected one.         assertThat(result, is(FAKE_STRING));     } }
Define behavior for the mock object

22. Example instrumented test
… import android.content.SharedPreferences; @RunWith(MockitoJUnitRunner.class) public class UnitTestSample {     private static final String FAKE_STRING = "HELLO WORLD";       Context mMockContext;       public void readStringFromContext_LocalizedString() {
        // Given a mocked Context injected into the object under test...         when(mMockContext.getString(R.string.hello_word))                 .thenReturn(FAKE_STRING);         ClassUnderTest myObjectUnderTest = new ClassUnderTest(mMockContext);         // ...when the string is returned from the object under test...         String result = myObjectUnderTest.getHelloWorldString();         // ...then the result should be the expected one.         assertThat(result, is(FAKE_STRING));     } }
When accessing R.string.hello_world,
return “HELLO_WORLD”

23. Example instrumented test
… import android.content.SharedPreferences; @RunWith(MockitoJUnitRunner.class) public class UnitTestSample {     private static final String FAKE_STRING = "HELLO WORLD";       Context mMockContext;       public void readStringFromContext_LocalizedString() {
        // Given a mocked Context injected into the object under test...         when(mMockContext.getString(R.string.hello_word))                 .thenReturn(FAKE_STRING);         ClassUnderTest myObjectUnderTest = new ClassUnderTest(mMockContext);         // ...when the string is returned from the object under test...         String result = myObjectUnderTest.getHelloWorldString();         // ...then the result should be the expected one.         assertThat(result, is(FAKE_STRING));     } }
Now create an instance of the class you want to test.

24. Example instrumented test
… import android.content.SharedPreferences; @RunWith(MockitoJUnitRunner.class) public class UnitTestSample {     private static final String FAKE_STRING = "HELLO WORLD";       Context mMockContext;       public void readStringFromContext_LocalizedString() {
        // Given a mocked Context injected into the object under test...         when(mMockContext.getString(R.string.hello_word))                 .thenReturn(FAKE_STRING);         ClassUnderTest myObjectUnderTest = new ClassUnderTest(mMockContext);         // ...when the string is returned from the object under test...         String result = myObjectUnderTest.getHelloWorldString();         // ...then the result should be the expected one.         assertThat(result, is(FAKE_STRING));     } }
Call a method on that instance.

25. Example instrumented test
… import android.content.SharedPreferences; @RunWith(MockitoJUnitRunner.class) public class UnitTestSample {     private static final String FAKE_STRING = "HELLO WORLD";       Context mMockContext;       public void readStringFromContext_LocalizedString() {
        // Given a mocked Context injected into the object under test...         when(mMockContext.getString(R.string.hello_word))                 .thenReturn(FAKE_STRING);         ClassUnderTest myObjectUnderTest = new ClassUnderTest(mMockContext);         // ...when the string is returned from the object under test...         String result = myObjectUnderTest.getHelloWorldString();         // ...then the result should be the expected one.         assertThat(result, is(FAKE_STRING));     } }
Assert that it behaved as expected