… interface

…support class

…ed (and fail) for unknown reason

See xwp/wp-dev-lib#270

Test init() and redirect_canonical_amp().
@todo continue with these,
and consider a better way to test
redirect_canonical_amp().
That uses wp_safe_redirect,
which throws an error.

is_customize_preview_iframe() and
register_paired_hooks().

Test add_hooks, send_header(), and
register_content_embed_handlers().

Test methods related to AMP templates,
and get_current_canonical_url().

Test 2 methods:
get_comment_form_state_id() and
filter_comment_form_defaults().

There's a check for is_customize_preview() around add_action().
But the callback dequeue_customize_preview_scripts()
has its own check for is_customize_preview_iframe().
And that has a check for is_customize_preview().
So this ensures that the body of the callback
never runs.
Maybe I misread the intent of this, though.
This also adds unit tests.

These variables are only used once,
so they can simply be passed to the array.

There's already a phpcs:disable at the top of the method.
And a phpcs:enable at the bottom.

There was a minor conflict in:
test-class-amp-theme-support.php.
Retain both edits.

Before, merging in 0.7, there was an amp-default <link>.
But test_validate_non_amp_theme() also output that.
And that stored the script in $wp_styles->done.
So it wasn't output again, and the test failed.
So reset $wp_styles, so it gets re-instantiated.