Fix #3090: Removing context initialization from test setup

[sierisimo]

Fix #3090:

Explanation

In the ExplorationActivityTest dagger has been setup and the context is now injected, the line in the setup is unnecessary as noted in #3090

Screenshot of tests

Checklist

• The PR title starts with "Fix #bugnum: ", followed by a short, clear summary of the changes. (If this PR fixes part of an issue, prefix the title with "Fix part of #bugnum: ...".)
• The PR explanation includes the words "Fixes #bugnum: ..." (or "Fixes part of #bugnum" if the PR only partially fixes an issue).
• The PR follows the style guide.
• The PR does not contain any unnecessary auto-generated code from Android Studio.
• The PR is made from a branch that's not called "develop".
• The PR is made from a branch that is up-to-date with "develop".
• The PR's branch is based on "develop" and not on any other branch.
• The PR is assigned to an appropriate reviewer in both the Assignees and the Reviewers sections.

[anandwana001]

Thanks, @sierisimo for sending your first PR.
Few suggestions:

1. Follow the checklist in the PR description and mark done if it is completed or done in the PR.
2. PR title should be in the format Fix #bugnum: ...
3. PR description should have format Fixes #bugnum: ...
4. Branch name looks good to me.
5. For the screenshot, could you confirm if this is an espresso test result or a robolectric test result? What we actually looking for is an espresso test result screenshot.
6. As you are a new contributor, you can simply mention the issue author in the comment in your PR once the PR is ready for review.
7. You can join our Gitter channel where we have all the communication with all other contributors - https://gitter.im/oppia/oppia-android
8. Also, you need to comment on issue, that you want to work on it so the issue author can assign the issue to you.

[sierisimo]

Sorry for the inconvenience, I originally checked the checklist options I though I satisfied but later though it was something the reviewer will mark.

For the espresso part, how can I show/confirm the test is espresso test? Sharing screenshot of the adb instruction run by android studio or maybe running a concrete gradle task?

Thanks for your comment!

[anandwana001]

As from the Icon in your screenshot, I can confirm this is the espresso test only. But, I think this will be helpful and learning too if you check here on how to run espresso test - https://developer.android.com/codelabs/advanced-android-kotlin-training-testing-basics#4
and Robolectric test - https://github.com/oppia/oppia-android/wiki/Oppia-Android-Testing#running-robolectric-tests

[anandwana001]

LGTM

[sierisimo]

Thanks for those resources, I'm used to running tests but seeing the @Config and @LooperMode confused me about it.

Thanks for your review! I'll wait for @BenHenning

[BenHenning]

Thanks @sierisimo. LGTM.