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In this video we'll see how to use 'onData' to match with Views that aren't shown!
Important Imports
import static org.hamcrest.CoreMatchers.is;
import static org.hamcrest.CoreMatchers.instanceOf;
import static org.hamcrest.core.AllOf.allOf;
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We've just finished testing our
editText with Espresso, and
0:00
now it's time that we move
on to testing our spinner.
0:03
Let's start in the Arrange section,
0:08
by copying over the given color
variable from MainActivity test.
0:10
To find the right spinner item to click
we'll be using the with text a few so
0:26
let's create a new string
variable named spinner item text.
0:31
And set it equal to the string Green.
0:39
In the act section, we need to
start by clicking on our spinner.
0:46
Let's type onView(withId(
R.id.colorspinner),
0:49
and then, .perform, and for
0:56
the view action, let's pass in click.
1:00
Now that we can see all
the items in the spinner,
1:09
we need to click on
the one that says Green.
1:11
Lets use control or
command D to duplicate this line and
1:15
then replace the withId view matcher
with the withText view matcher.
1:18
And instead of passing in an ID, let's
pass in our spinnerItemText variable.
1:27
At this point if we run the test again.
1:33
We can see that we're successfully
changing the background color to green.
1:45
Nice.
1:50
But before we move on to asserting,
we need to talk about an edge case.
1:51
What if we had a spinner with 100 items
and we wanted to click on the 98th item.
1:56
Well, the spinner only shows so
many items at a time.
2:03
So if we try to click on the 98th item,
it's not going to be there.
2:07
And we'll get an error.
2:12
To fix this,
2:14
Espresso gives us the onData method,
which we use to replace the onView method.
2:15
OnView only searches through
the view hierarchy, but
2:21
onData searches through everything.
2:25
So if you want to click on that 98th item,
onData is the way to go.
2:28
Let's refactor our spinnerItem
click to use onData instead.
2:32
Then let's copy in a few other imports
we'll be needing from the teachers'
2:41
notes below.
2:45
And paste them up here
in the import section.
2:47
Next we need to provide an object matcher
to match the object we're trying to click.
2:53
So get rid of what's inside
our onData method now.
2:59
Because instead of a view matcher,
we need to be providing an object matcher.
3:05
So inside the parentheses.
3:09
Let's first use the all of matcher.
3:11
The all of matcher takes in other
matchers as parameters and if all
3:17
of those other matchers report a match the
all of matcher will report a match too.
3:23
For the first parameter of all of method,
3:30
lets pass on (is(instance0f(String.class).
3:35
We don't want to try and
3:41
match our spinner item text to
something that isn't a string, then for
3:43
the second matcher parameter lets
pass in is(spinner item text).
3:49
Now it will search through
the data in our app looking for
3:56
a string equal to our
spinner item text and
4:00
when it finds it, it will find
the associated view and perform a click.
4:04
Let's run our test again to make sure
we're still changing the background color.
4:11
Perfect.
4:24
Moving onto the assert
section we need to assert
4:25
that the background color of the app
is equal to the given color.
4:28
Let's grab the linear layout by
using the withIdViewMatcher.
4:33
OnView (withId of (R.Id.LinearLayout).
4:40
Then since were asserting we need to add
the check method, and now we just need
4:49
to matcher to check that the background
of our view matches the given color.
4:55
Unfortunately there isn't a matcher for
this.
5:02
So we'll just have to make our own.
5:05
Let's add a line above this one and
declare a new bounded matcher variable.
5:08
Named background color matcher.
5:14
And let's set it equal
to new bounded matcher.
5:23
Bounded matchers give us a way to match
only on objects of a given class.
5:29
But autocomplete didn't
fill this part in for us.
5:34
So first, in the matchesSafely method,
let's replace object item with
5:38
(LinearLayout linearLayout).
5:44
Then between BoundedMatcher and the
parentheses, let's add angle brackets and
5:51
inside lets type view
on the linear layout.
5:57
And import view.
6:05
This tells our matcher to
only be looking at views and
6:08
then to only match on linear layouts.
6:12
To finish off the errors,
6:16
we just need to provide the class
we're looking for as a parameter.
6:18
Linearlayout.class and add a semicolon.
6:23
Finally we just need to return whether or
6:29
not we have a match in
the matchesSafely method.
6:32
To check if we have a match,
6:35
let's start by copying over the actual
color variable from MainActivityTest.
6:37
And pasting it into our
matchesSafely method.
6:46
Then let's delete Activity to
leave our linear layout parameter,
6:53
And let's finish up by returning
the outcome of givenColor == actualColor.
7:01
The describeTo method is what
we'll see in an error message
7:10
if something doesn't match.
7:13
And while we don't have to fill it in,
it's quick and it doesn't hurt.
7:15
Let's type description.appendText and
7:19
then for the text let's pass in
7:25
background color should equal: and
7:29
then outside of the quotes.
7:35
Plus given color.
7:39
Semi colon.
7:42
All right.
7:46
We finally finished our custom
matcher all that's left is to use it.
7:47
Inside the check method.
7:52
Let's use the matches view assertion.
7:53
And pass in our background color matcher.
7:55
Then let's use Alt+enter
to fix this warning.
8:03
And it looks like Android Studio
just wanted us to specify the types
8:06
over here as well.
8:11
Okay moment of truth.
8:14
Let's run the test and see what happens.
8:17
All right.
8:30
You're really getting good at this stuff.
8:32
Now, let's comment out the act lines.
8:33
And if we run the test again we should
be able to see our description.
8:40
There it is.
8:54
Background color should equal
about negative seventeen million.
8:55
AKA color dark green.
9:01
Now let's un-comment the act section and
9:02
then let's conquer our final foe and
the next video.
9:06
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