Add busted unit testing framework for lua code

[zrdaley]

What this PR does / why we need it:

Currently Lua code is only tested through e2e tests and no unit tests exist.

This adds busted as a unit testing framework for Lua code and adds documentation within the developer guide.

Which issue this PR fixes: N/A

[zrdaley]

/assign @bowei

[codecov-io]

Codecov Report

Merging #2379 into master will increase coverage by 0.19%.
The diff coverage is 83.33%.

@@            Coverage Diff             @@
##           master    #2379      +/-   ##
==========================================
+ Coverage   40.72%   40.91%   +0.19%     
==========================================
  Files          74       74              
  Lines        5228     5252      +24     
==========================================
+ Hits         2129     2149      +20     
- Misses       2807     2809       +2     
- Partials      292      294       +2

Impacted Files	Coverage Δ
internal/file/bindata.go	60.17% <83.33%> (+2.75%)	⬆️

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[aledbf]

/assign @ElvinEfendi

[ElvinEfendi]

@zrdaley why did bindata change?

[zrdaley]

@ElvinEfendi it seems like all lua changes require bindata to be updated? Or at least anytime new files/directories are added. In this case adding rootfs/etc/nginx/lua/test/balancer-test.lua and rootfs/etc/nginx/lua/test/up.sh seemed make changes.

[ElvinEfendi]

    go-bindata -nometadata -o internal/file/bindata.go -prefix="rootfs" -pkg=file -ignore=Dockerfile -ignore=".DS_Store" rootfs/...

yeah looks like any update under rootfs, for some reason I thought it is only nginx.tmpl that requires it

[ElvinEfendi]

/approve

[aledbf]

This is required to avoid polluting the filesystem when we run the tests. Before go-bindata it was required to run as root

[ElvinEfendi]

can we enforce _test pattern rather than -test?

[zrdaley]

Unfortunately no. Initially this is the pattern I used. However, this causes errors because these files are converted to go source code in the bindata.go file and underscores are not allowed in go naming convention. It was causing the ./hack/verify-gofmt.sh test to fail.

[ElvinEfendi]

Hmm, are you sure? Looking at https://github.com/kubernetes/ingress-nginx/blob/master/hack/verify-gofmt.sh#L32 bindata.go should not be checked by ./hack/verify-gofmt.sh.

[zrdaley]

Yes, and that's the problem. go-bindata creates functions for each converted lua file in bindata.go (https://github.com/Shopify/ingress/blob/2b6696573c77a32cc3f4ba3f333e39b5bd746bbd/internal/file/bindata.go#L170). So lua files here can't be named with underscores in them or it will create a go function with an underscore which isn't allowed by the formatter.

[ElvinEfendi]

@zrdaley you could just do something like following?

out=$("${GOLINT}" -min_confidence=0.9 "${package}" | grep -v '(should not use dot imports|internal/file/bindata.go)' || :)

[ElvinEfendi]

it is not too different than your fix, but with your changes the variable name PACKAGES is not correct anymore

[aledbf]

/approve

[aledbf]

@zrdaley please rebase

[aledbf]

@ElvinEfendi add your lgtm when you think this is ready to go

[ElvinEfendi]

waiting for the rebase

[ElvinEfendi]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: aledbf, ElvinEfendi, zrdaley

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