Interactivity: Fix string index warning

[sirreal]

Fix the following warning when using an interactivity bind directive with a short attribute name, e.g. wp-data-bind--id.

Warning: Uninitialized string offset 4 in /var/www/html/wp-includes/interactivity-api/class-wp-interactivity-api.php on line 579

Trac ticket: https://core.trac.wordpress.org/ticket/60758

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Props jonsurrell, cbravobernal, swissspidy, gziolo.

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[sirreal]

👋 @c4rl0sbr4v0 @DAreRodz for review.

[cbravobernal]

LGTM

[swissspidy]

Possible to add tests for this?

[sirreal]

I tried adding tests and would like to, but I couldn't get them to fail on the warning, that may be a configuration option or my lack of knowledge, but I couldn't find any way of saying "warnings on this test should cause the test to fail."

There is actually a test that has a short attribute and should hit this code path, but it doesn't fail the test suite or seem to generate any warning:

wordpress-develop/tests/phpunit/tests/interactivity-api/wpInteractivityAPI-wp-bind.php

Lines 368 to 381 in a6783cf

	/**
	* Tests handling of bindings within nested tags.
	*
	* @ticket 60356
	*
	* @covers ::process_directives
	*/
	public function test_wp_bind_handles_nested_bindings() {
	$html = '<div data-wp-bind--id="myPlugin::state.id"><img data-wp-bind--width="myPlugin::state.width"></div>';
	list($p) = $this->process_directives( $html );
	$this->assertEquals( 'some-id', $p->get_attribute( 'id' ) );
	$p->next_tag();
	$this->assertEquals( '100', $p->get_attribute( 'width' ) );
	}

[gziolo]

I can see the error when running tests. I might be valuable to add another test that handles the boolean value:

The same check needs to be added in another line which only will trigger when passing true:

if ( is_bool( $result ) && strlen( $bound_attribute ) > 5 && '-' === $bound_attribute[4] ) {

[sirreal]

Good catch! I pushed a change to apply the same fix to that warning.

[gziolo]

You also need a test like the one I shared to trigger the warning in the second updated line. The value needs to be true.

[sirreal]

I pushed a test that does error if I revert the changes.

[sirreal]

I'll address the test failures.

[sirreal]

I fixed the tests and updated them to use assertSame. We're comparing values of types we expect to match, mostly strings, so assertSame is the appropriate assertion.

This is something to address across the interactivity tests when comparing strings to strings.

[gziolo]

Excellent, tests pass locally. I no longer see the warnings. I could confirm that unit tests hit both conditions by manually changing the comparisons strlen( $bound_attribute ) > 5 using value 1.

[swissspidy]

Committed in https://core.trac.wordpress.org/changeset/57835