Fix part of #5070: Display empty answer message in Math expressions input interaction.

[Vishwajith-Shettigar]

Explanation

Fix part of #5070, In Math expressions Interaction UI, leave submit button enabled when answer is empty. Show an error on submitting an empty answer.

MathExpressionInteractionsViewTestActivity added to accessibility_label_exemptions and test_file_exemptions files.

Numeric expression

numerix_expression.webm

Algebraic expression

algebraic_expression.webm

Math equation

math_equation.webm

Essential Checklist

• [x] 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: ...".)
• [ ] Any changes to scripts/assets files have their rationale included in the PR explanation.
• [x] The PR follows the style guide.
• [x] The PR does not contain any unnecessary code changes from Android Studio (reference).
• [x] The PR is made from a branch that's not called "develop" and is up-to-date with "develop".
• [x] The PR is assigned to the appropriate reviewers (reference).

For UI-specific PRs only

If your PR includes UI-related changes, then:

• Add screenshots for portrait/landscape for both a tablet & phone of the before & after UI changes
• For the screenshots above, include both English and pseudo-localized (RTL) screenshots (see RTL guide)
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[Vishwajith-Shettigar]

@adhiamboperes, PTAL.

[oppiabot[bot]]

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

[Vishwajith-Shettigar]

@adhiamboperes, PTAL.

[oppiabot[bot]]

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

[oppiabot[bot]]

Hi @Vishwajith-Shettigar, 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[bot]]

Hi @Vishwajith-Shettigar, 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[bot]]

Hi @Vishwajith-Shettigar, 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]

@theMr17, could you please take a review pass on this PR? I had earlier requested some changes, please verify that they have been addressed, and please assign back to me once there is no comment to be addressed from your side.

[oppiabot[bot]]

Unassigning @theMr17 since the review is done.

[oppiabot[bot]]

Hi @Vishwajith-Shettigar, it looks like some changes were requested on this pull request by @theMr17. PTAL. Thanks!

[Vishwajith-Shettigar]

Thank you @theMr17 for reviewing, assigning back to you, PTAL.

[oppiabot[bot]]

Unassigning @theMr17 since they have already approved the PR.

[oppiabot[bot]]

Assigning @BenHenning for code owner reviews. Thanks!

[theMr17]

@theMr17, could you please take a review pass on this PR? I had earlier requested some changes, please verify that they have been addressed, and please assign back to me once there is no comment to be addressed from your side.

@adhiamboperes PTAL. I have reviewed the PR and this LGTM now. I have also verified that your earlier requested changes have been addressed.

[Vishwajith-Shettigar]

@adhiamboperes, PTAL.

[oppiabot[bot]]

Unassigning @adhiamboperes since the review is done.

[oppiabot[bot]]

Hi @Vishwajith-Shettigar, it looks like some changes were requested on this pull request by @adhiamboperes. PTAL. Thanks!

[Vishwajith-Shettigar]

Thank you @BenHenning, PTAL.

[Vishwajith-Shettigar]

@BenHenning, PTAL.

[oppiabot[bot]]

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