PHPCS 3.3.2: add XSD schema to ruleset

jrfnl commented 6 years ago

Dependency Version

When the PHP_CodeSniffer dependency is at least version 3.3.2 (not yet released at the time of writing), then take the actions below.

Action checklist

[x] Add the XSD schema attributes to the various rulesets, like so:
```
<ruleset name="My Project"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:noNamespaceSchemaLocation="https://raw.githubusercontent.com/squizlabs/PHP_CodeSniffer/master/phpcs.xsd">
```
Note: we could probably use a relative schema location like ../vendor/squizlabs/php_codesniffer/phpcs.xsd as people are required to install WPCS with Composer, so we can rely on the xsd to be available in that location.
[x] Validate the current ruleset against the schema and update it to comply if necessary.
[x] Verify whether the Travis XML validation checks will take the newly added schema into account and if not, adjust them so they will.

Rationale:

An XSD schema definition file defines the expected format of an XML file. It defines the elements and attributes which can be used in the XML file and in which order those can be used.

Adding an XSD schema reference to an XML file will allow for stricter validation of the file to ensure it is valid for the purpose for which it is intended to be used, in this case: that it is a valid ruleset for use with PHPCS.

References:

The XSD schema file was added in PHPCS 3.2.0 via PR https://github.com/squizlabs/PHP_CodeSniffer/pull/1433
The new array format for properties was introduced in PHPCS 3.3.0 / PR https://github.com/squizlabs/PHP_CodeSniffer/pull/1665
The XSD was updated to allow for the new array format in PHPCS 3.3.2 via https://github.com/squizlabs/PHP_CodeSniffer/issues/2151

jrfnl commented 5 years ago

For an example of how to implement this: https://github.com/squizlabs/PHP_CodeSniffer/pull/2187

dingo-d commented 5 years ago

Should we put this in 0.2.0 release or later?

jrfnl commented 5 years ago

I think it can be safely added now as long as the Travis check is added in a build against PHPCS master.

Note: since then one more oversight has been discovered in the PHPCS XSD file, but I don't think this will be a problem for TRTCS as I don't think that feature is used in the ruleset.

There is an open PR upstream to fix it which is expected to go into PHPCS 3.5.0: https://github.com/squizlabs/PHP_CodeSniffer/pull/2491

dingo-d commented 5 years ago

I'll tag this for later, as it's not a crucial feature for this release 🙂

jrfnl commented 5 years ago

As it is such a simple change which can contribute significantly to the QA, I've just pulled it now.

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