More descriptive error messages for UndefinedVariable

[jolyonb]

This PR updates the error messages presented to students when they try to use an invalid variable or function in a formula.

Current behavior:

• Using an invalid variable yields the message: Invalid input: x not permitted in answer. (using variable x)
• Using an invalid function yields the message: Invalid input: f not permitted in answer. (using function f)

Note that there is no mention of how x or f are actually being used in the formula. This is particularly frustrating to students who write something like x(1+x), where x*(1+x) is required (and accounts for a significant percentage of forum posts in math-based courses). The error message simply tells students that x is not permitted, because x has been treated as an invalid function.

This PR addresses this issue by providing more intelligent error messages to students:

• Using an invalid variable yields the message: Invalid Input: x not permitted in answer as a variable (using variable x)
• Using a valid variable with the wrong case yields the message: "Invalid Input: X not permitted in answer as a variable (did you mean x?)" (using invalid variable X, valid variable x)
• Using an invalid function yields the message: Invalid Input: f not permitted in answer as a function (using function f)
• Using a valid function with the wrong case yields the message: Invalid Input: Sin not permitted in answer as a function (did you mean sin?) (using invalid function Sin, valid function sin)
• Using a variable as a function, likely an indicator of a missing multiplication sign, yields the message: Invalid Input: x not permitted in answer as a function (did you forget to use * for multiplication?) (using variable x)

This is a WIP while we update old tests and construct new ones.

Mentions: @pdpinch @jefrench

[openedx-webhooks]

Thanks for the pull request, @jolyonb! I've created OSPR-2394 to keep track of it in JIRA. JIRA is a place for product owners to prioritize feature reviews by the engineering development teams.

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[mduboseedx]

@jolyonb Feel free to ping me when this is ready to be reviewed

[mduboseedx]

@jolyonb Are you still working on this PR? Is there anything we can do to help?

[jolyonb]

@mduboseedx I'm done with the coding part; all that's needed are tests I believe. @pdpinch was going to work on those...

[pdpinch]

jenkins run all

[pdpinch]

@mduboseedx this has (passing) tests now and is ready for review.

[mduboseedx]

@edx/learner-product This adds a more descriptive and helpful error message for learners when inputting formulas. Could you take a look?

[jolyonb]

Bump?

[mduboseedx]

@edx/learner-product @marcotuts Have you had a chance to give this a look?

[marcotuts]

This can move to awaiting prioritization on the engineering side, but this is actually something for the educator team to review, not learner as it turns out. :) @mduboseedx

[jolyonb]

Ok guys, bump? This one is pretty straightforward...

[mduboseedx]

@edx/educator-all @scottrish Do you know when this could be given a review?

[jolyonb]

Bump...

[mduboseedx]

@jolyonb I'm sorry for the long delay. Unfortunately our Educator team will actually be unable to review any PRs for the next few weeks. I'll see if I can find someone else to give this a look over.

[jolyonb]

jenkins run bokchoy

[jolyonb]

jenkins run bokchoy

[jolyonb]

I'm getting bokchoy errors:

PageLoadError: Timed out waiting to load page '<common.test.acceptance.pages.lms.course_home.CourseHomePage object at 0x7f0312e5d710>' at URL 'http://localhost:8003/courses/course-v1:test_org+15062424598459186396361364419204103494+test_run/course/'

Is this a known bad test? I've run the tests three times now and gotten the same error message three times. I don't touch anything related to this test with this PR...

[pdpinch]

jenkins run bokchoy

[mduboseedx]

@jolyonb Sorry for the delay as I was out of the office last week. You may want to try a rebase and we can then run the bokchoy tests again.

[pdpinch]

Now I'm even more confused. The bokchoy tests ended in failure, yet there are no test failures? I guess we'll try again...

jenkins run bokchoy

[pdpinch]

jenkins run lettuce

[edx-status-bot]

Your PR has finished running tests. There were no failures.

[jolyonb]

@mduboseedx This is now tested and ready for review.

[mduboseedx]

@pdpinch As this is an Educator type of pull request, if you feel comfortable with the code then you are welcome to merge this change.

[openedx-webhooks]

@jolyonb 🎉 Your pull request was merged!

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[edx-pipeline-bot]

EdX Release Notice: This PR has been deployed to the staging environment in preparation for a release to production on Wednesday, September 19, 2018.

[edx-pipeline-bot]

EdX Release Notice: This PR has been deployed to the production environment.