Cypress crashes completely on some network requests

[vitalybe]

Current behavior:

Cypress crashes completely (the browser and the application) with the following stack after I navigate to a page that does multiple AJAX requests:

TypeError: Cannot read property 'length' of null
    at Writable.onWrite [as _write] (/Users/vitalyb/Library/Caches/Cypress/3.6.0/Cypress.app/Contents/Resources/app/packages/server/lib/util/stream_buffer.js:13:46)
    at doWrite (_stream_writable.js:415:12)
    at writeOrBuffer (_stream_writable.js:399:5)
    at Writable.write (_stream_writable.js:299:11)
    at Duplexify._write (/Users/vitalyb/Library/Caches/Cypress/3.6.0/Cypress.app/Contents/Resources/app/packages/server/node_modules/duplexify/index.js:212:22)
    at doWrite (/Users/vitalyb/Library/Caches/Cypress/3.6.0/Cypress.app/Contents/Resources/app/packages/server/node_modules/duplexify/node_modules/readable-stream/lib/_stream_writable.js:405:139)
    at writeOrBuffer (/Users/vitalyb/Library/Caches/Cypress/3.6.0/Cypress.app/Contents/Resources/app/packages/server/node_modules/duplexify/node_modules/readable-stream/lib/_stream_writable.js:394:5)
    at Duplexify.Writable.write (/Users/vitalyb/Library/Caches/Cypress/3.6.0/Cypress.app/Contents/Resources/app/packages/server/node_modules/duplexify/node_modules/readable-stream/lib/_stream_writable.js:303:11)
    at IncomingMessage.ondata (_stream_readable.js:706:22)
    at IncomingMessage.emit (events.js:199:15)
    at IncomingMessage.Readable.read (_stream_readable.js:497:10)
    at flow (_stream_readable.js:970:34)
    at Request.pipeOnDrainFunctionResult (_stream_readable.js:774:7)
    at Request.emit (events.js:194:13)
    at ClientRequest.<anonymous> (/Users/vitalyb/Library/Caches/Cypress/3.6.0/Cypress.app/Contents/Resources/app/packages/server/node_modules/request/request.js:778:10)
    at ClientRequest.emit (events.js:194:13)
    at TLSSocket.ondrain (internal/http.js:31:44)
    at TLSSocket.emit (events.js:194:13)
    at onwriteDrain (_stream_writable.js:495:12)
    at afterWrite (_stream_writable.js:483:5)
    at onwrite (_stream_writable.js:476:7)
    at WriteWrap.onWriteComplete [as oncomplete] (internal/stream_base_commons.js:91:10)

TypeError: Cannot read property 'length' of null
    at Writable.onWrite [as _write] (/Users/vitalyb/Library/Caches/Cypress/3.6.0/Cypress.app/Contents/Resources/app/packages/server/lib/util/stream_buffer.js:13:46)
    at doWrite (_stream_writable.js:415:12)
    at writeOrBuffer (_stream_writable.js:399:5)
    at Writable.write (_stream_writable.js:299:11)
    at Duplexify._write (/Users/vitalyb/Library/Caches/Cypress/3.6.0/Cypress.app/Contents/Resources/app/packages/server/node_modules/duplexify/index.js:212:22)
    at doWrite (/Users/vitalyb/Library/Caches/Cypress/3.6.0/Cypress.app/Contents/Resources/app/packages/server/node_modules/duplexify/node_modules/readable-stream/lib/_stream_writable.js:405:139)
    at writeOrBuffer (/Users/vitalyb/Library/Caches/Cypress/3.6.0/Cypress.app/Contents/Resources/app/packages/server/node_modules/duplexify/node_modules/readable-stream/lib/_stream_writable.js:394:5)
    at Duplexify.Writable.write (/Users/vitalyb/Library/Caches/Cypress/3.6.0/Cypress.app/Contents/Resources/app/packages/server/node_modules/duplexify/node_modules/readable-stream/lib/_stream_writable.js:303:11)
    at IncomingMessage.ondata (_stream_readable.js:706:22)
    at IncomingMessage.emit (events.js:199:15)
    at IncomingMessage.Readable.read (_stream_readable.js:497:10)
    at flow (_stream_readable.js:970:34)
    at Request.pipeOnDrainFunctionResult (_stream_readable.js:774:7)
    at Request.emit (events.js:194:13)
    at ClientRequest.<anonymous> (/Users/vitalyb/Library/Caches/Cypress/3.6.0/Cypress.app/Contents/Resources/app/packages/server/node_modules/request/request.js:778:10)
    at ClientRequest.emit (events.js:194:13)
    at TLSSocket.ondrain (internal/http.js:31:44)
    at TLSSocket.emit (events.js:194:13)
    at onwriteDrain (_stream_writable.js:495:12)
    at afterWrite (_stream_writable.js:483:5)
    at onwrite (_stream_writable.js:476:7)
    at WriteWrap.onWriteComplete [as oncomplete] (internal/stream_base_commons.js:91:10)```

Desired behavior:

I'd like it not to crash.

Steps to reproduce: (app code and test code)

I'm performing the test on an internal site, so I can't really reproduce it.

Versions

cypress@3.6.0
MacOS, High Sierra, 10.13.6 (17G7024)

[vitalybe]

Adding here: https://github.com/cypress-io/cypress/blob/develop/packages/server/lib/util/stream_buffer.js#L13

The following fixes that:

    if(!chunk || !buffer) {
      return;
    }

[brian-mann]

This is likely due to the XHR mocking changes in 3.6.0 - I can think of a few situations where if requests are leaking from one test into another - they could possibly cause this.

If then a request goes out and signals it should be stubbed - but the state doesn't have a record for it, the request will fail, the socket will be closed, but I believe it'll still have a buffer that needs draining, and because we null out the internal request it'll end up being null - which leads to this failure.

[cypress-bot]

The code for this is done in cypress-io/cypress#5605, but has yet to be released.
We'll update this issue and reference the changelog when it's released.

[cypress-bot]

The code for this is done in cypress-io/cypress#5605, but has yet to be released.
We'll update this issue and reference the changelog when it's released.

[cypress-bot]

Released in 3.6.1.