Tests consistently failing in Travis CI

[gareth-robinson]

Summary

Since the end of 2017 all Pull requests are all failing at the test-headers test; this appears to be because of two issues

1. The 'catch invalid characters error' test works on node v4 & v6, but fails on v8.
2. The 'IPv6 Host Header' test fails in all builds

Simplest Example to Reproduce

These are test bugs rather than functional bugs - compare the CI builds for the recent pull requests and see they all fail in the same way.

Current Behavior

1. Headers characters tests fails on node v8

The 'catch invalid characters error' test works on node v4 & v6, but fails on v8.
This test appears to be asserting node functionality; there isn't anything in the request code that actually throws the error message the test looks for. The error message that node throws has changed between versions:

v6 - https://github.com/nodejs/node/blob/v6.x/lib/_http_outgoing.js#L359
v8 - https://github.com/nodejs/node/blob/master/lib/_http_outgoing.js#L496

So what's the best solution here?

1. Remove the test, since it is checking node functionality rather than the library functionality?
   Or if the test needs to exist to check that request properly rethrows the error
2. Change request to catch the error and throw it's own consistent error?
3. Change the test to check accept either error message?

I'd prefer 3. here I think.

2. The 'IPv6 Host Header' test fails in all builds

There are a number of pages on this e.g.
travis-ci/travis-ci#4964 (comment)
travis-ci/travis-ci#9207
https://github.com/njh/travis-ipv6-test

Basically it appears that IPv6 is not supported on travis-ci, and only worked previously as 'a by-product of where we've been hosting' (first link above). The second link above suggests it stopped working around the end of October, which would match when the pull requests started failing.

So what's the best solution here? I've only got one solution, so others are welcome...

1. Since the environments don't support IPv6, then don't run the IPv6 test. Pass some environment flag that allows that particular test to be skipped.

Context

Blocking pull requests :)

Your Environment

travis-ci

[gareth-robinson]

Created pull request #2923 with alterations for this bugs

[simov]

Fixed in: #2923