[Merged by Bors] - Add sleep to make data race less likely

[fasmat]

Motivation

This adds sleeps to tests in the fetch package to hopefully make data races less likely.

Description

libp2p/go-libp2p-pubsub internally uses a go routine with a for loop that only returns when the context is canceled. See the code here: https://github.com/libp2p/go-libp2p-pubsub/blob/19ffbb3a482caecabb8520917c631e3047a78094/pubsub.go#L668-L671

Since this signal might not reach the go routine before the test ends the log that is emitted might use the test logger of a different test causing a race. Since there is no way to not use a global logger or any signal back from PubSub that the go routine exited, the only thing we can do without changing libp2p/go-libp2p-pubsub is to sleep in the test for some time and hope that ensures the go routine exited.

Test Plan

existing tests pass and are less flaky

TODO

• Explain motivation or link existing issue(s)
• Test changes and document test plan
• Update documentation as needed
• Update changelog as needed

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.1%. Comparing base (c25d28c) to head (0b53859).
Report is 2 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff           @@
##           develop   #6231   +/-   ##
=======================================
  Coverage     82.0%   82.1%           
=======================================
  Files          309     309           
  Lines        34120   34120           
=======================================
+ Hits         28010   28018    +8     
+ Misses        4327    4320    -7     
+ Partials      1783    1782    -1     

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[fasmat]

bors merge

[spacemesh-bors]

Build failed:

• systest-status

[fasmat]

bors merge

[spacemesh-bors]

Build failed:

• ci-status

[fasmat]

bors merge

[spacemesh-bors]

Build failed:

• systest-status

[fasmat]

bors merge

[spacemesh-bors]

Pull request successfully merged into develop.

Build succeeded:

• systest-status
• ci-status