Warn users on importing dependencies as absolute paths

[mstoykov]

part of #1089

[codecov-commenter]

Codecov Report

Merging #2078 (459c426) into master (b232e97) will decrease coverage by 0.07%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #2078      +/-   ##
==========================================
- Coverage   72.16%   72.08%   -0.08%     
==========================================
  Files         181      180       -1     
  Lines       14289    14248      -41     
==========================================
- Hits        10311    10271      -40     
  Misses       3351     3351              
+ Partials      627      626       -1     

Flag	Coverage Δ
ubuntu	72.01% <0.00%> (-0.08%)	⬇️
windows	71.73% <0.00%> (-0.06%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
js/initcontext.go	87.87% <0.00%> (-4.68%)	⬇️
lib/testutils/httpmultibin/httpmultibin.go	90.00% <0.00%> (-1.12%)	⬇️
lib/executor/vu_handle.go	94.39% <0.00%> (-0.94%)	⬇️
cmd/outputs.go	0.00% <0.00%> (ø)
output/statsd/datadog.go

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[codebien]

Suggested change

	i.logger.Warnf("you import '%s' with an absolute path, this won't be cross platform and likely will not work if"+
	" you move the script between machines. Also it might not work on k6 cloud if it doesn't have `file://` in front",
	i.logger.Warnf("you import '%s' with an absolute path, this won't be cross platform and likely will not work if"+
	" you move the script between machines or in cloud. You should use `file://` in front to have the full cross platform and cloud finally supported",

I would make "the suggestion" more explicit

[mstoykov]

The thing is that "full cross platform" isn't true, as just moving the script between machines will still not work. It will work if you archive it and run the archive, but not if you than unarchive it on a different machine.

[mstoykov]

The reality of it is that the correct way for something to be cross-platform and cross-machine (as the OS is not the only problem) is to not use absolute paths at all.

So I really do prefer if that is the sentiment we sent more than "this won't work in the cloud if you are on Windows and use absolute paths without file://"

cc @na-- @imiric

[na--]

👎, this is going to trigger for *nix file paths, which are not problematic. Also, the warning will be shown multiple times, once for every VU init.

[mstoykov]

this is going to trigger for Linux file paths,

They still are not

1. cross platform
2. cross machine in most cases, even if k6 archive + k6 run archive.tar on different machines will work (hopefully)

[na--]

See my other point about the warning being shown once per VU, I submitted my review prematurely and edited the message. Also, if you want this warning to be for all absolute paths (which I don't), it should also be shown for file:// imports, which it isn't.

[na--]

LGTM in general, made an inline comment with a suggestion for a better warning message