Fix regex used in currency API endpoint

[ryelle]

Fixes #77 – the regex used in the API endpoint was a malformed pattern, at least for how gutenberg uses these. This caused gutenberg to crash. This PR fixes the endpoint regex by setting the currency code to exactly 3 letters.

[timmyc]

Change looks good - wondering if g-berg needs to have some logic to prevent other plugins from crashing it in this manner.

Does look like there is one failing test related to this change on the branch ( there are a couple other failures, but guessing those are on master too ):

There was 1 failure:

1) Data_API::test_register_routes
Failed asserting that an array has the key '/wc/v3/data/currencies/(?P<currency>[\w-]{3}+)'.

/srv/www/wordpress-develop/public_html/src/wp-content/plugins/wc-api-dev/tests/unit-tests/data.php:32

[ryelle]

I tried to run the tests to fix them, and ran into this error:

Warning: require_once(/vagrant/content/plugins/woocommerce/tests/framework/factories/class-wc-unit-test-factory-for-webhook.php): failed to open stream: No such file or directory in /vagrant/content/plugins/wc-api-dev/tests/bootstrap.php on line 107

It looks like the webhook tests were removed, see woocommerce/woocommerce@0ac915d – so I've removed those lines from our tests too.

[timmyc]

Thanks for picking up the webhook test trash too! I think i had an old version of WC on my vvv instance when I ran the tests yesterday.