Traffic Ops unit tests: TestGetMonitoringJSON sometimes fails

[srijeet0406]

What does this PR (Pull Request) do?

• This PR fixes Traffic Ops unit tests: TestGetMonitoringJSON sometimes fails #4919

Which Traffic Control components are affected by this PR?

• Traffic Ops

What is the best way to verify this PR?

Follow the steps in #4919

cd traffic_ops/traffic_ops_golang/monitoring
go test -c
failures=0
for ((i = 0; i < 100; i++)); do
  ./monitoring.test || (( ++failures ))
done;
echo "Failed ${failures} times out of ${i}"

should result in 0 failures, always.

If this is a bug fix, what versions of Traffic Control are affected?

• master

The following criteria are ALL met by this PR

• This PR includes tests
• I have explained why documentation is unnecessary
• This PR does not include an update to CHANGELOG.md
• This PR includes any and all required license headers
• This PR does not include a database migration
• This PR DOES NOT FIX A SERIOUS SECURITY VULNERABILITY

[zrhoffman]

Although the tests do pass, is there a way to accomplish this that makes use of the existing code? Take a look at the sortable types in this file and how they implement interface.Less() and interface.Swap() so they can use sort.Sort().

[srijeet0406]

@zrhoffman I changed it so that it gets called from the sortCaches method now. The servers sorting is different, in the sense that we need to double sort the slice, once by the server hostname, and the second sorting will be by the interface names of each server.

[zrhoffman]

The servers sorting is different, in the sense that we need to double sort the slice, once by the server hostname, and the second sorting will be by the interface names of each server

Right, but for the interface sorting part, is there a way to use a SortableInterfaces type and sort on that?

If we can use the same code pattern for sorting across different Go interfaces, it will make it easier for the next maintainer who has to modify this code.

[srijeet0406]

@zrhoffman Should be done now

[zrhoffman]

Awesome, looks great and passes consistently.