fix(challenges): Add check for function name in test cases

[vs1682]

Changed a test case where it checks that the user defined function name
matches to that given in instructions.

BREAKING CHANGE: no breaking change

Closes #15591

Pre-Submission Checklist

• Your pull request targets the staging branch of freeCodeCamp.
• Branch starts with either fix/, feature/, or translate/ (e.g. fix/signin-issue)
• You have only one commit (if not, squash them into one commit).
• All new and existing tests pass the command npm test. Use git commit --amend to amend any fixes.

Type of Change

• Small bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds new functionality)
• Breaking change (fix or feature that would change existing functionality)
• Add new translation (feature adding new translations)

Checklist:

• Tested changes locally.
• Closes currently open issue (replace XXXX with an issue no): Closes Use a Mixin Under Object Oriented Programming FCC Beta #15591

Description

In issue #15591 user was able to pass a test with function name as glideMixing, but the test case says that

Your code should declare a glideMixin variable that is a function.

This change checks the function name to be exact as given in test case.

[camperbot]

@vs1682 thanks for the PR.
Do not include issue numbers and following keywords in commit messages.
Please review our Guidelines for Contributing, thank you!

[Manish-Giri]

This is not the underlying problem here. Refer - ☝️ [July 11, 2017 2:24 PM](https://gitter.im/FreeCodeCamp/Contributors?at=596517f089aea4761d8a9ba4

[vs1682]

@Manish-Giri Sorry my bad. Did you find anything on this?