Travis CI: Cache $HOME/.npm

[ntwb]

Description

The addition of Puppeteer in #5618 adds an ~75MB binary to node_modules as part of the npm install process, this PR adds $HOME/.npm to the Travis CI cache with the goal to improving subsequent Travis CI build/job times.

How Has This Been Tested?

Testing this PR results to follow in comments from Travis CI test results

Screenshots (jpeg or gifs if applicable):

Types of changes

Build tooling improvement to allow faster Travis CI build results

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code has proper inline documentation.

[ntwb]

Via https://travis-ci.org/WordPress/gutenberg/caches

Branch	Time	Size
Pushes
master	20 days ago	110.58MB
Pull Requests
PR.4398	20 days ago	0.00MB
PR.4725	20 days ago	0.00MB
PR.5269	20 days ago	0.00MB
PR.5279	19 minutes ago	141.87MB
PR.5423	20 days ago	54.69MB
PR.5507	20 days ago	54.69MB
PR.5854	about 5 hours ago	0.00MB

As can be seen from the above table the only cache recently used by Travis CI was build PR.5279 of #5279 of which I pushed up changes to (and subsequently broke whilst rebasing 😏 )

I believe the reason why the previous cache located at $HOME/.composer/cache is not currently caching anything is due to Composer runs in Docker containers, why there is no cache for $HOME/.phpbrew will need further investigation.

Via https://travis-ci.org/WordPress/gutenberg/caches after this PR Travis CI completed successfully

Branch	Time	Size
Pull Requests
PR.5865	4 minutes ago	141.87MB

[ntwb]

Checking that npm cache is added:

Travis Job #17883.1

This confirms previusly that npm wasn't cached:

https://travis-ci.org/WordPress/gutenberg/jobs/359640282#L454

Setting up build cache
$ export CASHER_DIR=$HOME/.casher
0.21s$ Installing caching utilities
0.00s
4.78sattempting to download cache archive
fetching PR.5279/cache-linux-trusty-e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855--php-5.5.tgz
fetching PR.5279/cache--php-5.5.tgz
fetching master/cache-linux-trusty-e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855--php-5.5.tgz
found cache
0.01s
2.26sadding /home/travis/.composer/cache to cache
creating directory /home/travis/.composer/cache
adding /home/travis/.phpbrew to cache
creating directory /home/travis/.phpbrew
adding /home/travis/.npm to cache
npm is not yet cached

This confirms npm is now cached:

https://travis-ci.org/WordPress/gutenberg/jobs/359640282#L3623

The command "npm run ci || exit 1" exited with 0.
cache.2
store build cache
0.00s
3.98schange detected (content changed, file is created, or file is deleted):
/home/travis/.npm/anonymous-cli-metrics.json
/home/travis/.npm/_cacache/content-v2/sha1/00/a9/f7387556e27038eae232caa372a6a59b665a
/home/travis/.npm/_cacache/content-v2/sha1/00/c1/cdb1aca71112cdf0cf6126c2ed6b457ccdbc
/home/travis/.npm/_cacache/content-v2/sha1/01/8e/c7a4ce7e3a86cb9141be519d24c8faa981b5
/home/travis/.npm/_cacache/content-v2/sha1/01/fc/bbb393463a548f2f466cce16dece49db908f
/home/travis/.npm/_cacache/content-v2/sha1/02/89/88bb7fe8b2e6645676d82052587d440b02d3
/home/travis/.npm/_cacache/content-v2/sha1/03/19/1c432cb6eea168bb77f3a55ffdccb8978514
/home/travis/.npm/_cacache/content-v2/sha1/03/71/ab4ae0bdd720d4166d7dfda64ff7a445a6c0
/home/travis/.npm/_cacache/content-v2/sha1/04/21/e339fd71419b3da13d129b3979040230476e
/home/travis/.npm/_cacache/content-v2/sha1/04/5f/9782d011ae9a6803ddd382b24392b3d890f7
/home/travis/.npm/_cacache/content-v2/sha1/04/e6/926f662895354f3dd015203633b857297e2c
/home/travis/.npm/_cacache/content-v2/sha1/05/37/cb79daf59b59a1a517dff706c86ec039162e
/home/trav
...
changes detected, packing new archive
uploading archive

[aduth]

Related: #5854