World-Class Testing Development Pipeline for Android

Pedro V. Gómez Sánchez - pedro@karumi.com - @pedro_g_s - github.com/pedrovgs
World-Class Testing Development Pipeline for Android
Pedro Vicente Gómez Sánchez
Senior Mobile Developer at Karumi
pedro@karumi.com
@pedro_g_s
github.com/pedrovgs

Alberto Gragera
Technical Director
Jorge Barroso
Google Developer Expert
Davide Mendolia
Senior Full Stack Engineer
Sergio Gutierrez
Senior Mobile Engineer

Let’s talk about testing!

This talk starts with some common
problems.

What do we have to test and how?

What if our code is not testable?

Just because our tests are passing doesn’t
mean your code is working.

Any conclusions?

We are doing something wrong if we can’t trust
our tests. We need a solution.

The Solution: Testable Code + Testing Pipeline

The Software Architecture used has to
hide implementation details.

Dependency Inversion Principle is
going to guide your Architecture.
DIP is the most important S.O.L.I.D.
principle.

Architecture - Testable Code
Activity
View
Presenter
Use
Case
Repository
Repository
Domain
Model
Data
Source
Data
Source
Data Source
Implementation
Data Source
Implementation
Use
Case
Use
Case

Architecture is not enough.

Testing Development Pipeline

Your Testing Development Pipeline should
define what you are going to test and how.

What do I want to test?

Test my code implements the business
requirements.

Test my API Client, HTTP requests/responses
and JSON parsing, are working as expected.

Test the user is watching in the App UI the
expected messages.

In other words…

Test our Business Logic independently of
frameworks or libraries.
Test our integration with the API.
Test our application UI.

These three points define part of the Testing
Development Pipeline.
These three points define what we want to test.

How are we going to test this?

Think in the test scope and try to check the state
of the software at the end of the test execution.
Use the Dependency Inversion Principle to be
able to use test doubles to simulate different test
scenarios and adjust the test scope.
Business Logic Tests

Show me the code!

Check the state of the
software at the end of
the test execution

Implementation
Details are replaced
using Test Doubles.
The SUT is the
GameBoy, the GBZ80
and the GPU.

Infrastructure needed?

The usage of test
doubles are the key to
adjust the test scope.
The Application architecture
will help use to hide
implementation details
applying the dependency
inversion principle

Now we can test our business logic
without depending on any framework
or library. Inside an isolated
environment.
The Result

Start a fake server we have under control
checking the API client is working given some
preconfigured scenarios.
API Client tests

Given some HTTP
responses the final
authentication state is
correct.

Given a Json file with
the response, an http
status code, and an
endpoint the parsing is
correct.

Initializes a fake http
server where we can
configure responses.

Now we can check if our integration
with the API Client is working as it
should.
The Result

UI Tests
Replace some dependencies using test doubles from
the testing application to be able to simulate different
scenarios and check the UI is showing the correct
information.

Code Injected from
the test application.

Asserts from the UI
point of view.

Asserts from the User
Interface point of
view.

Helper methods or
different creational
patterns to create
initial scenarios.

Configure your
dependency injection
library from your
Application class.

Mocking Library
Helper Methods

Replace Application’s
dependency container
with a custom
configuration.

Now we can write UI tests easily.
The Result

The Testing Development Pipeline is complete
now.
Now we know what to test and how.

Now we can trust our tests.

Tools and libraries?

Business Logic Tests
● JUnit.
● Mockito.

API Client Tests
● JUnit.
● Mockito.
● MockWebServer.

UI Tests
● JUnit.
● Mockito.
● Robolectric.
● Espresso.
● Dagger.

References
● World-Class Testing Development Pipeline for Android blog post series.
● Kata Contacts. GitHub Repository.
● Kata TODO API Client. GitHub Repository.
● Kata Super Heroes. GitHub Repository.
● Android GameBoy Emulator. GitHub Repository.
● Google Testing Blog. Testing state vs interaction.

Questions?

World-Class Testing Development Pipeline for Android

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