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In this video we'll write our very first Android unit test!
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It's time for testing.
0:00
Over in the project pane,
0:02
let's create a new test class by
right-clicking on the test folder.
0:03
New > Java Class, and
let's name it MainActivityTest.
0:10
And let's choose to add this and
all other new files to gif.
0:20
Now let's create our first Android test to
test the functionality of our edit text.
0:26
Let's create a new test
method @Test public void and
0:32
let's name it editTextUpdatesTextView and
0:39
make sure it throws an exception.
0:45
Let's start this method by commenting and
the three As of testing.
0:53
First, we arrange the objects under test,
then we act on those objects and
0:57
finally we assert that we
get the expected result.
1:04
Starting with the Arrange section,
1:11
let's first create a new string
variable named given string.
1:13
And set it equal to test123.
1:19
Then we need to call set text on our
edit text and pass in our new string,
1:25
but before we can do that, our edit
text needs to exist and before our
1:31
edit text can exist, main activity
needs to have already been created.
1:36
Sounds like we need
an instance of our activity.
1:42
Let's create a new main activity
field at the top of the class.
1:45
Main activity and we'll call it activity.
1:50
Then let's create a new @Before
method to set up our main activity.
1:55
Let's name it setUp public void setUp and
brackets.
2:02
Next, inside our setUp method
let's initialize our field
2:10
to a new main activity object.
2:14
Activity = new MainActivity.
2:15
Then on the next line,
let's call activity.onCreate and
2:20
pass a null for the saved instance state.
2:27
Saved instance state is always null
the first time you start an app, so
2:30
passing a null is no problem.
2:34
Now that we've initialized
our MainActivity object and
2:38
called onCreate,
our edit text should exist and
2:41
we should be able to access it
by using activity.edittext.
2:45
Getting back to the Arrange section of
our test, let's update our edit text
2:49
by calling activity.editText.setText and
2:55
passing in givenString.
3:07
Nice.
3:10
Moving on to the act section,
we need a way to trigger our editText.
3:11
Let's see how it's done in the activity,
but instead of navigating to the activity,
3:16
let's right click on main activity test
up here and select split vertically.
3:21
Then let's close the copy
on the left side and
3:28
now we can easily see main activity and
main activity test at the same time.
3:32
Looking over at main activity,
if we want our text view to update,
3:39
it looks like we need to
call on editor action and
3:45
pass in an action ID of
editorInfo.IME_Action_Done.
3:49
And luckily, we can do that pretty easily.
3:55
Back in the act section of our test,
3:59
just type
activity.editText.onEditorAction and
4:03
pass in editorInfo.IME_Action_Done.
4:11
And that takes care of the act section.
4:17
Now let's close MainActivity to give
the whole screen back to our test.
4:19
Finally, we just need to
assert that our text view was
4:25
updated with the correct text.
4:28
Let's start by creating a new
string variable named actualString.
4:30
To store what's actually in our text view,
and
4:38
let's set it equal to
activity.textView.getText().toString();.
4:43
Then we just need to assert that our given
string is equal to our actual string.
4:51
On the next line let's type
assertEquals and the parentheses
4:57
and then use Alt+Enter to
add the static import, and
5:05
let's scroll a bit to choose one of
these from the org.Junit package
5:10
to stay consistent with our other imports.
5:17
Then we just need to include our
expected value, given string
5:20
and then our actual value, actual string,
add a semi colon and there we go.
5:27
In the next video,
we'll run our test and see what happens.
5:34
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