fix: cy.route swallows the error about missing fixture #7818

[przemuh]

• Closes cy.route swallows the error about missing fixture #7818
• Closes Cannot read property '__error' of null error thrown when providing null.json to cy.fixture() #8010

User facing changelog

• cy.route throws an error when fixture cannot be found.
• In addition I've fixed the fixture command which raised an error for null.json. BTW. did you know that if the fixture contains following key in the returned object __error then cy.fixture throws an error :) ?

Additional details

• Why was this change necessary?
  To provide better error message in case of missing fixture or problem with parsing

• What is affected by this change?
  cy.route calls cy.fixture if response meets criteria of fixture shortcut fx: | fixture:. With this additional check we can raise an error even before HTTP request is sent.

How has the user experience changed?

If fixture file doesn't exists, or there is a problem with fixture, cy.route will raise an error.

Before:

Now:

PR Tasks

• Have tests been added/updated?

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[jennifer-shehane]

@przemuh There's a failure with this implementation when run through our cypress-example-kitchensink repo. https://circleci.com/gh/cypress-io/cypress/395839

You should be able to clone the repo and run it in your branch with yarn start, add the project and see the failure from the files spec. Can you track down what introduced this failure?

[przemuh]

@jennifer-shehane Please check it now, it should be ok :)

The problem was in waiting command. After adding additional wrap with fixutre the name of the command is no longer route. That's why I've added additional check if subject of the command has a prop. To be honest I am not sure about this solution and I would be more than happy if you could double check it :)

[jennifer-shehane]

This null.json fixture should have already worked per #5562. But weirdly enough, it seems that we only fixed when this it's passed via fx: there: https://github.com/cypress-io/cypress/blob/develop/packages/driver/cypress/integration/commands/xhr_spec.js#L1870:L1870

I opened an issue to detail the null.json error here: #8010

Dismissing my previous review for more thorough code review

[bahmutov]

super, tests were added, so that's good. I just need an answer to my question for

return cy.fixture(options.response.replace(fixturesRe, '')).then(() => route())

[jennifer-shehane]

Hey @przemuh, there were some requests for changes. It should be good to go after those are addressed. Do you have time to address them?

[przemuh]

Hey @jennifer-shehane. This week I am on vacations🏖 without access to my computer...I will be more than happy to address all comments but around Sunday evening CET. I hope that it will not be a problem 😅

[bahmutov]

super, I think this is fine now

[jennifer-shehane]

I've identified that this PR introduced a regression - where the fixture files take longer to load, especially at large fixture file sizes, sometimes timing out. Detailed here: #8181

[przemuh]

@jennifer-shehane I am really sorry about that :( I hope you will forgive me ;)

Here is a pull request with fix/revert: #8215