Intercept does not return locally cached data and times out

[asithade]

Current behavior

When trying to intercept a request, if the request is already cached locally the intercept method is unable to intercept the query. Workarounds for caching previously mentioned deleting various headers that determine whether the server returns cached data or not, do not work as it doesn't intercept the query at all.

If I disabled caching via the console's network tab, the query works every time and I'm able to wait for it to complete.

Desired behavior

If the data is cached locally, return the local response. If the intended behavior of Cypress is to mimic a user's experience, then we should not have to append query parameters to get a fresh set of data each time a query is presented.

Test code to reproduce

  it('successfully loads', () => {
    cy.visit('/');

    cy.intercept('GET', `${projectServicesAPI}/projects/search**`, (req) => {
      delete req.headers.Authorization;
    }).as('projects');

    // Ensure that the projects are loaded
    cy.wait('@projects').its('response').should('deep.include', {
      statusCode: 200
    });
  });

The response from the API sends the following cache control header:

cache-control: private, max-age=600

Versions

Cypress Version: 6.2.1
Browser: Electron 87
OS: Mac

[jennifer-shehane]

@flotwig Is this issue related to this? #14277

[flotwig]

@jennifer-shehane that one seems to be for 304 responses, this issue seems to be about requests that are never sent at all, so different

If the intended behavior of Cypress is to mimic a user's experience, then we should not have to append query parameters to get a fresh set of data each time a query is presented.

@asithade Well, it is mimicing the user's experience... your browser caches responses in the real world!

But in the real world, responses don't change like that :)

I am not sure how Cypress can easily solve this problem for users, since we are intercepting requests at the HTTP level.

My current favorite idea is Cypress clearing the browser's cache between each test, so that it acts closer to your expectations. There is probably not an easy way for Cypress to manage the browser's cache during the runtime of your test, since clearing cache mid-test could affect the outcome. What do you think?

In the mean time, you can use the workaround of disabling cache automatically before running tests (Chromium-family browsers only):

before(() => Cypress.automation(
  'remote:debugger:protocol', 
  { 
    command: 'Network.setCacheDisabled',
    params: { cacheDisabled: true }
  }
))

[rooby]

@flotwig Where does that workaround code go? Can you provide a little more context?

I have tried adding to on('before:spec', (spec) => { in plugins, and to before() and beforeEach() in my spec files and none of those seemed to have any effect.

I am testing using Electron via cypress open.

If I run my single spec it works but then if I click the re-run icon it fails due to this issue.

[rooby]

I seem to have got it working for me with this code:

if (Cypress.browser.family === 'chromium') {
  Cypress.automation('remote:debugger:protocol', {
    command: 'Network.enable',
    params: {}
  });
  Cypress.automation('remote:debugger:protocol', {
    command: 'Network.setCacheDisabled',
    params: { cacheDisabled: true }
  });
}

The way I use it currently is I have a load page function that I call on beforeEach() of all my tests, which runs the above code, then intercepts some requests, loads the requested page and waits on the intercepted requests.

[flotwig]

It should work to use it in your support file, or on a per-spec-file basis. You can read more about before and beforeEach: https://docs.cypress.io/guides/core-concepts/writing-and-organizing-tests.html#Hooks

Closing since the workaround of disabling cache is all that can really be done.

[shwarcu]

@flotwig

Closing since the workaround of disabling cache is all that can really be done.

I think there is actually something to be done here - changing the default Cypress behaviour to disable network caching for each test. Since Cypress is unable to intercept cached request it is natural to expect from Cypress to have caching disabled.

Could you please consider that?

[shwarcu]

@jennifer-shehane could we please revive this topic and think of a correct solution rather than workarounds?