Fix some instances of null array key access

src/wp-includes/class-wp-block-bindings-registry.php

@@ -249,11 +249,11 @@ public function get_registered( string $source_name ) {
 	 *
 	 * @since 6.5.0
 	 *
-	 * @param string $source_name The name of the source.
+	 * @param string|null $source_name The name of the source.
 	 * @return bool `true` if the block bindings source is registered, `false` otherwise.
 	 */
 	public function is_registered( $source_name ) {
-		return isset( $this->sources[ $source_name ] );
+		return isset( $source_name, $this->sources[ $source_name ] );
 	}
 
 	/**

src/wp-includes/class-wp-block-pattern-categories-registry.php

@@ -138,11 +138,11 @@ public function get_all_registered( $outside_init_only = false ) {
 	 *
 	 * @since 5.5.0
 	 *
-	 * @param string $category_name Pattern category name including namespace.
+	 * @param string|null $category_name Pattern category name including namespace.
 	 * @return bool True if the pattern category is registered, false otherwise.
 	 */
 	public function is_registered( $category_name ) {
-		return isset( $this->registered_categories[ $category_name ] );
+		return isset( $category_name, $this->registered_categories[ $category_name ] );
 	}
 
 	/**

src/wp-includes/class-wp-block-patterns-registry.php

@@ -238,11 +238,11 @@ public function get_all_registered( $outside_init_only = false ) {
 	 *
 	 * @since 5.5.0
 	 *
-	 * @param string $pattern_name Block pattern name including namespace.
+	 * @param string|null $pattern_name Block pattern name including namespace.
 	 * @return bool True if the pattern is registered, false otherwise.
 	 */
 	public function is_registered( $pattern_name ) {
-		return isset( $this->registered_patterns[ $pattern_name ] );
+		return isset( $pattern_name, $this->registered_patterns[ $pattern_name ] );
 	}
 
 	public function __wakeup() {

src/wp-includes/class-wp-block-styles-registry.php

@@ -181,12 +181,12 @@ public function get_registered_styles_for_block( $block_name ) {
 	 *
 	 * @since 5.3.0
 	 *
-	 * @param string $block_name       Block type name including namespace.
-	 * @param string $block_style_name Block style name.
+	 * @param string|null $block_name       Block type name including namespace.
+	 * @param string|null $block_style_name Block style name.
 	 * @return bool True if the block style is registered, false otherwise.
 	 */
 	public function is_registered( $block_name, $block_style_name ) {
-		return isset( $this->registered_block_styles[ $block_name ][ $block_style_name ] );
+		return isset( $block_name, $this->registered_block_styles[ $block_name ][ $block_style_name ] );
 	}
 
 	/**

src/wp-includes/class-wp-block-templates-registry.php

@@ -204,11 +204,11 @@ public function get_by_query( $query = array() ) {
 	 *
 	 * @since 6.7.0
 	 *
-	 * @param string $template_name Template name.
+	 * @param string|null $template_name Template name.
 	 * @return bool True if the template is registered, false otherwise.
 	 */
 	public function is_registered( $template_name ) {
-		return isset( $this->registered_templates[ $template_name ] );
+		return isset( $template_name, $this->registered_templates[ $template_name ] );
 	}
 
 	/**

tests/phpunit/tests/block-bindings/wpBlockBindingsRegistry.php

@@ -344,4 +344,16 @@ public function test_is_registered_for_known_source() {
 		$result = $this->registry->is_registered( self::$test_source_name );
 		$this->assertTrue( $result );
 	}
+
+	/**
+	 * Should return false when checking registration with an empty source name.
+	 *
+	 * @ticket 63957
+	 *
+	 * @covers WP_Block_Bindings_Registry::is_registered
+	 */
+	public function test_is_registered_with_empty_source_name() {
+		$result = $this->registry->is_registered( '' );
+		$this->assertFalse( $result );
+	}
 }

tests/phpunit/tests/block-pattern/wpBlockPatternCategoriesRegistry.php

@@ -0,0 +1,33 @@
+<?php
+/**
+ * Unit tests for WP_Block_Pattern_Categories_Registry::is_registered().
+ *
+ * @package WordPress
+ * @subpackage Blocks
+ * @since 6.9.0
+ *
+ * @group block-patterns
+ * @covers WP_Block_Pattern_Categories_Registry::is_registered
+ */
+
+class Tests_Block_Pattern_WPBlockPatternCategoriesRegistry extends WP_UnitTestCase {
+
+	/**
+	 * @ticket 63957
+	 */
+	public function test_is_registered_with_empty_param() {
+		$registry = WP_Block_Pattern_Categories_Registry::get_instance();
+
+		// Should return false when called with empty string.
+		$this->assertFalse( $registry->is_registered( '' ) );
+
+		// Should return false when called with null.
+		$this->assertFalse( $registry->is_registered( null ) );
+
+		// Should return false when called with false.
+		$this->assertFalse( $registry->is_registered( false ) );
+
+		// Should return false when called with 0.
+		$this->assertFalse( $registry->is_registered( 0 ) );
+	}
+}

tests/phpunit/tests/block-pattern/wpBlockPatternsRegistry.php

@@ -0,0 +1,81 @@
+<?php
+/**
+ * Tests for WP_Block_Patterns_Registry::is_registered().
+ *
+ * @package WordPress
+ * @subpackage Blocks
+ * @since 6.9.0
+ *
+ * @group block-patterns
+ *
+ * @covers WP_Block_Patterns_Registry::is_registered
+ */
+class Tests_Block_Pattern_WPBlockPatternsRegistry extends WP_UnitTestCase {
+
+	/**
+	 * Instance of the registry.
+	 *
+	 * @var WP_Block_Patterns_Registry
+	 */
+	protected $registry;
+
+	public function set_up() {
+		parent::set_up();
+		$this->registry = WP_Block_Patterns_Registry::get_instance();
+	}
+
+	public function tear_down() {
+		$this->registry = null;
+
+		parent::tear_down();
+	}
+
+	/**
+	 * @ticket 63957
+	 */
+	public function test_is_registered_returns_false_for_unregistered_pattern() {
+		$this->assertFalse( $this->registry->is_registered( 'my/pattern' ) );
+	}
+
+	/**
+	 * @ticket 63957
+	 */
+	public function test_is_registered_returns_true_for_registered_pattern() {
+		$this->registry->register(
+			'my/pattern',
+			array(
+				'title'   => 'My Pattern',
+				'content' => '<!-- wp:paragraph --><p>Test</p><!-- /wp:paragraph -->',
+			)
+		);
+
+		$this->assertTrue( $this->registry->is_registered( 'my/pattern' ) );
+	}
+
+	/**
+	 * @ticket 63957
+	 */
+	public function test_is_registered_returns_false_after_unregistering_pattern() {
+		$this->registry->register(
+			'my/pattern',
+			array(
+				'title'   => 'My Pattern',
+				'content' => '<!-- wp:paragraph --><p>Test</p><!-- /wp:paragraph -->',
+			)
+		);
+
+		$this->registry->unregister( 'my/pattern' );
+
+		$this->assertFalse( $this->registry->is_registered( 'my/pattern' ) );
+	}
+
+	/**
+	 * @ticket 63957
+	 */
+	public function test_is_registered_with_invalid_pattern_name() {
+		$this->assertFalse( $this->registry->is_registered( '' ) );
+		$this->assertFalse( $this->registry->is_registered( null ) );
+		$this->assertFalse( $this->registry->is_registered( false ) );
+		$this->assertFalse( $this->registry->is_registered( 0 ) );
+	}
+}

tests/phpunit/tests/block-styles/wpBlockStylesRegistry.php

@@ -0,0 +1,137 @@
+<?php
+/**
+ * Unit tests for WP_Block_Styles_Registry::is_registered().
+ *
+ * @package WordPress
+ * @subpackage Blocks
+ * @since 6.9.0
+ *
+ * @group block-styles
+ *
+ * @covers WP_Block_Styles_Registry::is_registered
+ */
+
+class Tests_Block_Styles_WPBlockStylesRegistryTest extends WP_UnitTestCase {
+
+	/**
+	 * WP_Block_Styles_Registry instance.
+	 *
+	 * @var WP_Block_Styles_Registry
+	 */
+	protected $registry;
+
+	public function setUp(): void {
+		parent::setUp();
+		$this->registry = WP_Block_Styles_Registry::get_instance();
+	}
+
+	public function tearDown(): void {
+		$this->registry = null;
+		parent::tearDown();
+	}
+
+	/**
+	 * @ticket 63957
+	 */
+	public function test_is_registered_returns_false_for_unregistered_style() {
+		$this->assertFalse(
+			$this->registry->is_registered( 'core/paragraph', 'fancy-style' ),
+			'Unregistered style should return false.'
+		);
+	}
+
+	/**
+	 * @ticket 63957
+	 */
+	public function test_is_registered_returns_true_for_registered_style() {
+		$block_name = 'core/paragraph';
+		$style_name = 'fancy-style';
+
+		$this->registry->register(
+			$block_name,
+			array(
+				'name'  => $style_name,
+				'label' => 'Fancy Style',
+			)
+		);
+
+		$this->assertTrue(
+			$this->registry->is_registered( $block_name, $style_name ),
+			'Registered style should return true.'
+		);
+	}
+
+	/**
+	 * @ticket 63957
+	 */
+	public function test_is_registered_returns_false_for_wrong_block() {
+		$block_name = 'core/paragraph';
+		$style_name = 'fancy-style';
+
+		$this->registry->register(
+			$block_name,
+			array(
+				'name'  => $style_name,
+				'label' => 'Fancy Style',
+			)
+		);
+
+		$this->assertFalse(
+			$this->registry->is_registered( 'core/image', $style_name ),
+			'Style registered for another block should return false.'
+		);
+	}
+
+	/**
+	 * @ticket 63957
+	 */
+	public function test_is_registered_returns_false_for_wrong_style_name() {
+		$block_name = 'core/paragraph';
+		$style_name = 'fancy-style';
+
+		$this->registry->register(
+			$block_name,
+			array(
+				'name'  => $style_name,
+				'label' => 'Fancy Style',
+			)
+		);
+
+		$this->assertFalse(
+			$this->registry->is_registered( $block_name, 'other-style' ),
+			'Non-existent style name should return false.'
+		);
+	}
+
+	/**
+	 * @ticket 63957
+	 */
+	public function test_is_registered_returns_false_for_empty_block_name() {
+		$style_name = 'fancy-style';
+		$this->assertFalse(
+			$this->registry->is_registered( '', $style_name ),
+			'Empty block name should return false.'
+		);
+	}
+
+	/**
+	 * @ticket 63957
+	 */
+	public function test_is_registered_returns_false_for_empty_style_name() {
+		$block_name = 'core/paragraph';
+		$this->assertFalse(
+			$this->registry->is_registered( $block_name, '' ),
+			'Empty style name should return false.'
+		);
+	}
+
+	/**
+	 * @ticket 63957
+	 */
+	public function test_is_registered_returns_false_for_both_empty_params() {
+		$this->assertFalse(
+			$this->registry->is_registered( '', '' ),
+			'Both empty block and style name should return false.'
+		);
+	}
+}

tests/phpunit/tests/block-templates/WpBlockTemplatesRegistry.php

@@ -247,6 +247,16 @@ public function test_is_registered() {
 		self::$registry->unregister( $template_name );
 	}
 
+	/**
+	 * @ticket 63957
+	 *
+	 * @covers ::is_registered
+	 */
+	public function test_is_registered_with_invalid_param() {
+		$this->assertFalse( self::$registry->is_registered( '' ) );
+		$this->assertFalse( self::$registry->is_registered( null ) );
+	}
+
 	/**
 	 * Tests that unregister() correctly unregisters a registered template.
 	 *