feat(middleware): expose the memory filesystem (response.locals.fs)

[ferdinando-ferreira]

What kind of change does this PR introduce?
feature

Did you add tests for your changes?
yes

Summary
In order for the next middleware in line to be able to use the memory FileSystem created by webpack-dev-middleware (and access the files generated in memory by the compilation process) this commit passes the context.fs to the res.locals along with webpackStats when ServerSideRender is set to true.

Does this PR introduce a breaking change?
No

Other information
This is a PR is contingent on ServerSideRender not being removed from the middleware

[alexander-akait]

Looks good can we create test for this?

[ferdinando-ferreira]

If you mean a test in the npm run test suit it was created and is present in the same commit. Now if you mean a fully featured test like it was done for #336 I already did it, you can test it with

git clone --single-branch -b samples2 https://github.com/ferdinando-ferreira/webpack-dev-middleware.git
cd webpack-dev-middleware
npm install
cd samples
cd vue-ssr
npm install
npm run dev

It is the exact same vuejs SSR example.

[codecov]

Codecov Report

Merging #337 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master     #337   +/-   ##
=======================================
  Coverage   96.82%   96.82%           
=======================================
  Files           7        7           
  Lines         252      252           
=======================================
  Hits          244      244           
  Misses          8        8

Impacted Files	Coverage Δ
lib/middleware.js	94.33% <100%> (+0.1%)	⬆️
lib/fs.js	95.12% <0%> (-0.12%)	⬇️

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[alexander-akait]

@ferdinando-ferreira we need add test to avoid removing this in future (accidentally)

[michael-ciniawsky]

@ferdinando-ferreira Could you please add docs about this? (e.g to the README's SSR example)

[ferdinando-ferreira]

Could you please add docs about this? (e.g to the README's SSR example)

@michael-ciniawsky: done.

[ferdinando-ferreira]

@michael-ciniawsky: everything OK with the proposed changes?

[alexander-akait]

@michael-ciniawsky looks we should do minor release

[michael-ciniawsky]

Released in v3.3.0 🎉