From fe54c03d8f80ee5ec78a1565ffeb40ab205f7aa3 Mon Sep 17 00:00:00 2001
From: Luis Herranz <luisherranz@gmail.com>
Date: Thu, 19 Oct 2023 22:27:06 +0200
Subject: [PATCH] Fix server processing of an empty `data-wp-context` directive
 (#55482)

* Add failing test

* Fix the test

* Fix WPCS

* Add a test for an empty directive
---
 .../directives/wp-context.php                 |  15 +--
 .../directives/wp-context-test.php            | 102 ++++++++++++++++++
 2 files changed, 107 insertions(+), 10 deletions(-)

diff --git a/lib/experimental/interactivity-api/directives/wp-context.php b/lib/experimental/interactivity-api/directives/wp-context.php
index bf3014c5772d72..7d92b0ac7b0c67 100644
--- a/lib/experimental/interactivity-api/directives/wp-context.php
+++ b/lib/experimental/interactivity-api/directives/wp-context.php
@@ -18,16 +18,11 @@ function gutenberg_interactivity_process_wp_context( $tags, $context ) {
 	}
 
 	$value = $tags->get_attribute( 'data-wp-context' );
-	if ( null === $value ) {
-		// No data-wp-context directive.
-		return;
-	}
 
-	$new_context = json_decode( $value, true );
-	if ( null === $new_context ) {
-		// If the JSON is not valid, we still add an empty array to the stack.
-		$new_context = array();
-	}
+	$new_context = json_decode(
+		is_string( $value ) && ! empty( $value ) ? $value : '{}',
+		true
+	);
 
-	$context->set_context( $new_context );
+	$context->set_context( $new_context ?? array() );
 }
diff --git a/phpunit/experimental/interactivity-api/directives/wp-context-test.php b/phpunit/experimental/interactivity-api/directives/wp-context-test.php
index d3f44a5e4fd811..1277b016848cce 100644
--- a/phpunit/experimental/interactivity-api/directives/wp-context-test.php
+++ b/phpunit/experimental/interactivity-api/directives/wp-context-test.php
@@ -124,4 +124,106 @@ public function test_directive_keeps_working_after_malformed_context_objects() {
 			$context->get_context()
 		);
 	}
+
+	public function test_directive_keeps_working_with_a_directive_without_value() {
+		$context = new WP_Directive_Context();
+
+		$markup = '
+			<div data-wp-context=\'{ "my-key": "some-value" }\'>
+				<div data-wp-context>
+				</div>
+			</div>
+		';
+		$tags   = new WP_HTML_Tag_Processor( $markup );
+
+		// Parent div.
+		$tags->next_tag( array( 'tag_closers' => 'visit' ) );
+		gutenberg_interactivity_process_wp_context( $tags, $context );
+
+		$this->assertSame(
+			array( 'my-key' => 'some-value' ),
+			$context->get_context()
+		);
+
+		// Children div.
+		$tags->next_tag( array( 'tag_closers' => 'visit' ) );
+		gutenberg_interactivity_process_wp_context( $tags, $context );
+
+		// Still the same context.
+		$this->assertSame(
+			array( 'my-key' => 'some-value' ),
+			$context->get_context()
+		);
+
+		// Closing children div.
+		$tags->next_tag( array( 'tag_closers' => 'visit' ) );
+		gutenberg_interactivity_process_wp_context( $tags, $context );
+
+		// Still the same context.
+		$this->assertSame(
+			array( 'my-key' => 'some-value' ),
+			$context->get_context()
+		);
+
+		// Closing parent div.
+		$tags->next_tag( array( 'tag_closers' => 'visit' ) );
+		gutenberg_interactivity_process_wp_context( $tags, $context );
+
+		// Now the context is empty.
+		$this->assertSame(
+			array(),
+			$context->get_context()
+		);
+	}
+
+	public function test_directive_keeps_working_with_an_empty_directive() {
+		$context = new WP_Directive_Context();
+
+		$markup = '
+			<div data-wp-context=\'{ "my-key": "some-value" }\'>
+				<div data-wp-context="">
+				</div>
+			</div>
+		';
+		$tags   = new WP_HTML_Tag_Processor( $markup );
+
+		// Parent div.
+		$tags->next_tag( array( 'tag_closers' => 'visit' ) );
+		gutenberg_interactivity_process_wp_context( $tags, $context );
+
+		$this->assertSame(
+			array( 'my-key' => 'some-value' ),
+			$context->get_context()
+		);
+
+		// Children div.
+		$tags->next_tag( array( 'tag_closers' => 'visit' ) );
+		gutenberg_interactivity_process_wp_context( $tags, $context );
+
+		// Still the same context.
+		$this->assertSame(
+			array( 'my-key' => 'some-value' ),
+			$context->get_context()
+		);
+
+		// Closing children div.
+		$tags->next_tag( array( 'tag_closers' => 'visit' ) );
+		gutenberg_interactivity_process_wp_context( $tags, $context );
+
+		// Still the same context.
+		$this->assertSame(
+			array( 'my-key' => 'some-value' ),
+			$context->get_context()
+		);
+
+		// Closing parent div.
+		$tags->next_tag( array( 'tag_closers' => 'visit' ) );
+		gutenberg_interactivity_process_wp_context( $tags, $context );
+
+		// Now the context is empty.
+		$this->assertSame(
+			array(),
+			$context->get_context()
+		);
+	}
 }