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We've just finished using the Kito to unit test our app.

But now it's time to see what's so special about Robolectric.

To quote their website, Robolectric it is a unit test framework that defangs

the Android S.T.K. jar so you can test drive the development of your Android app.

Remember earlier when we were trying to start our activity and it didn't work.

Roboelectric aims to fix that by rewriting the Android classes

as they're being loaded making it possible for

them to run on your computer just like any other Java application.

First things first we need to add Roboelectric as a dependency.

Let's head over to our build.gradle file and add it.

It's in the teacher's notes below.

Then hit Sync Now and we're good to go.

Now let's get started with Robolectric by switching back to our main activity

test class.

Then let's comment out the lines in both the set up and

editTextUpdatesTextView methods.

Just like when we use my Kito we need to be sure that we're using the correct

test runner.

Let's add a run with annotation right above our class declaration

and then pass an Alt+enter to import it, and

we're passing in RobolectricGradleTestRunner.class.

At this point if we right click and

try to run main activity test, we'll get an error.

Field constants not specified in @Config annotation.

This is required when using RobolectricGradleTestRunner!

So right below our RunWith annotation, let's add the Config annotation.

And inside the parentheses,

let's specify the Constants field and

set it equal to BuildConfig.class.

Roboelectric use the build config class to figure out how to access our manifest,

resources and assets.

So it's important we add that.

Roboelectric would have a tough time being useful without knowing where anything is.

Now that we've specified the constants field, let's try running this again.

Darn another error.

Turns out Roboelectric doesn't yet support A.P.I. level twenty three.

Luckily we can fix this pretty easily

by adding another field to our config annotation.

After Bill.class let's add

comma Sdk equals Build.VERSION_CODES and

Alt+Enter to import build .LOLLIPOP.

Then let's try running it again.

And after it finishes downloading some things, success!

But why do we need to use Lollipop?

Why can't we just use Marshmellow?

Well after a new version of Android is released it just takes a while for

Roboelectric to get updated.

If you're curious about why the process takes so

long, check out the GitHub issue linked in the teacher's notes below.

Also the newest version of Roboelectric might just work with Marshmellow.

It just isn't officially released yet but that doesn't mean we can't use it.

Over on our build.gradle file,

let's change 3.0 to 3.1-SNAPSHOT.

A snapshot build represents the most recent changes and

isn't considered a stable release.

To use this snapshot build,

we'll also need to add a repository section above the dependency section.

Let's copy it in from the teacher's notes below and

then paste it right above the word dependencies.

Then let's sync the project and now thanks to our new snapshot

build we should be able to safely remove the SDK config parameter.

And it works.

Nice. We're all set up to start exploring unit

testing with Roboelectric.

In the next video, will see how to set up an activity for unit testing and

write our first Robolectric unit test.