add support for handling event streams / server sent events / SSE

[brian-mann]

fixes #1440
fixes #1111

[jijain786]

@jennifer-shehane @brian-mann

can you please advise where I can find the documentation/sample code for the SSE support from cypress - i tried to search on cypress.io and went through some of the commands like https://docs.cypress.io/api/commands/route.html

[drumslave-git]

Hi.
I also have issue with EventSource.
Peace of app code

var source = new EventSource('%REQUEST_URL%' + userId);
				source.onmessage = function(event) {
					// code here
				};
				source.onerror = function(event) {
					// code here
				};

In my spec

cy.route('GET', '**%REQUEST_URL% **').as('cleanup');
cy.wait('@cleanup').its('status').should('eq', 200)

And wait fails because request never happen, I can see it if Firefox debug console.

OS: Windows
Browser: Firefox
Cyoress: 4.5.0

[jennifer-shehane]

If you're experiencing a bug concerning SSE in Cypress, please open a new issue with a fully reproducible example that we can run. There may be a specific edge case with the issue that we need more detail to fix. Commented in a closed PR is not the best place for our team to address an issue.

Also, check out our community chat, it can be helpful for debugging or answering questions on how to use Cypress.