Need a validator for election files

[jberkus]

We need a script or test framework plugin that will validate election files, and prevent formatting errors. This validator could then be added as a presubmit test for organizations using elekto.

It would check for the following things:

• all files are present
• all YAML and MD files formatted correctly
• IDs are valid
• no MD formatting bugaboos, such as "@" characters
• all required fields are present

[upodroid]

On that note, elekto breaks down when an incorrectly formatted candidate-*.yaml is supplied. That needs to be fixed server side in addition to a script/linter that communities can run to ensure invalid files are not submitted.

The picture below was caused by merging knative/community#1193