Fix part of #5070: Display empty answer message in ratio input interaction

[theMr17]

Explanation

Fixes part of #5070

Enables the submit_answer_button when the pending answer is empty. Instead of disabling the button, an error message, stating "Enter a ratio to continue.", is now displayed when the user attempts to submit a blank answer.

RatioInputInteractionViewTestActivity is added to accessibility-label exemption as this is a test activity.

Screen.Recording.mp4

Essential Checklist

• The PR title and explanation each start with "Fix #bugnum: " (If this PR fixes part of an issue, prefix the title with "Fix part of #bugnum: ...".)
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[adhiamboperes]

@theMr17 is this ready for a full pass or are you looking for a preliminary review on approach? Please convert to ready and assign to me if the former.

[theMr17]

@adhiamboperes, please do a preliminary review of the approach. I will proceed to write tests after that.

[adhiamboperes]

@theMr17, I have left some suggestions, but the overall approach looks good to me.

[theMr17]

@adhiamboperes PTAL

[oppiabot]

Unassigning @theMr17 since a re-review was requested. @theMr17, please make sure you have addressed all review comments. Thanks!

[adhiamboperes]

Thanks @theMr17! This LGTM.

Thanks for moving the ratio tests to their own suite as well.

[oppiabot]

Unassigning @adhiamboperes since they have already approved the PR.

[oppiabot]

Assigning @BenHenning for code owner reviews. Thanks!

[oppiabot]

Hi @theMr17, I'm going to mark this PR as stale because it hasn't had any updates for 7 days. If no further activity occurs within 7 days, it will be automatically closed so that others can take up the issue.
If you are still working on this PR, please make a follow-up commit within 3 days (and submit it for review, if applicable). Please also let us know if you are stuck so we can help you!

[oppiabot]

Hi @theMr17, I'm going to mark this PR as stale because it hasn't had any updates for 7 days. If no further activity occurs within 7 days, it will be automatically closed so that others can take up the issue.
If you are still working on this PR, please make a follow-up commit within 3 days (and submit it for review, if applicable). Please also let us know if you are stuck so we can help you!

[adhiamboperes]

@BenHenning, this PR is blocked on codeowner, PTAL.

[BenHenning]

Thanks @theMr17! Really sorry about the late review here. I just had two small comments, otherwise the PR LGTM.

[theMr17]

@BenHenning PTAL

[oppiabot]

Unassigning @theMr17 since a re-review was requested. @theMr17, please make sure you have addressed all review comments. Thanks!

[BenHenning]

Thanks @theMr17! Please make sure to respond to addressed comments on future PRs. Otherwise the PR LGTM.

[theMr17]

Thanks @theMr17! Please make sure to respond to addressed comments on future PRs. Otherwise the PR LGTM.

Thanks @BenHenning, I will surely keep that in mind.