Don't cache not valid taxonomy frontend pages and stop applying optimizations

inc/Engine/Cache/ServiceProvider.php

@@ -27,6 +27,7 @@ class ServiceProvider extends AbstractServiceProvider {
 		'expired_cache_purge_subscriber',
 		'preload_caches_query',
 		'cache_config',
+		'taxonomy_subscriber',
 	];
 
 	/**
@@ -75,5 +76,6 @@ public function register(): void {
 		$this->getContainer()->add( 'cache_config', ConfigSubscriber::class )
 			->addArgument( $this->getContainer()->get( 'options' ) )
 			->addArgument( $this->getContainer()->get( 'options_api' ) );
+		$this->getContainer()->addShared( 'taxonomy_subscriber', TaxonomySubscriber::class );
 	}
 }

inc/Engine/Cache/TaxonomySubscriber.php

@@ -0,0 +1,71 @@
+<?php
+namespace WP_Rocket\Engine\Cache;
+
+use WP_Rocket\Event_Management\Subscriber_Interface;
+
+/**
+ * Subscriber for the taxonomy frontend pages.
+ */
+class TaxonomySubscriber implements Subscriber_Interface {
+	/**
+	 * {@inheritdoc}
+	 */
+	public static function get_subscribed_events() {
+		return [
+			'do_rocket_generate_caching_files' => 'disable_cache_on_not_valid_taxonomy_pages',
+			'rocket_buffer'                    => [ 'stop_optimizations_for_not_valid_taxonomy_pages', 1 ],
+		];
+	}
+
+	/**
+	 * Disable caching invalid taxonomy frontend pages.
+	 *
+	 * @param bool $can_cache Filter callback passed value.
+	 * @return bool
+	 */
+	public function disable_cache_on_not_valid_taxonomy_pages( $can_cache ) {
+		if ( $this->is_not_valid_taxonomy_page() ) {
+			return false;
+		}
+
+		return $can_cache;
+	}
+
+	/**
+	 * Stop optimizing those invalid taxonomy pages by returning empty html string,
+	 * So it fall back to the normal page's HTML.
+	 *
+	 * @param string $html Page's buffer HTML.
+	 * @return string
+	 */
+	public function stop_optimizations_for_not_valid_taxonomy_pages( $html ) {
+		return $this->is_not_valid_taxonomy_page() ? '' : $html;
+	}
+
+	/**
+	 * Check if we are on the taxonomy frontend page, but it's not valid url query.
+	 *
+	 * @return bool (True when not valid taxonomy page, False if it's a valid one)
+	 */
+	private function is_not_valid_taxonomy_page() {
+		if ( ! is_category() && ! is_tag() && ! is_tax() ) {
+			return false;
+		}
+
+		$term_id = get_queried_object_id();
+		if ( empty( $term_id ) ) {
+			return false;
+		}
+
+		global $wp;
+
+		$term_link = get_term_link( $term_id );
+		if ( is_wp_error( $term_link ) ) {
+			return false;
+		}
+
+		$current_link = home_url( add_query_arg( [], $wp->request ?? '' ) );
+
+		return untrailingslashit( $term_link ) !== untrailingslashit( $current_link );
+	}
+}

inc/Engine/Optimization/Buffer/Optimization.php

@@ -97,7 +97,13 @@ public function maybe_process_buffer( $buffer ) {
 		 *
 		 * @param string $buffer The page content.
 		 */
-		$buffer = (string) apply_filters( 'rocket_buffer', $buffer );
+		$filtered_buffer = (string) apply_filters( 'rocket_buffer', $buffer );
+
+		if ( empty( $filtered_buffer ) ) {
+			$this->log_last_test_error();
+			$this->log( 'Empty buffer.', [], 'error' );
+			return $buffer;
+		}
 
 		$this->log( 'Page optimized.', [], 'info' );
 
@@ -108,7 +114,7 @@ public function maybe_process_buffer( $buffer ) {
 		 */
 		do_action( 'rocket_after_process_buffer' );
 
-		return $buffer;
+		return $filtered_buffer;
 	}
 
 	/**

inc/Plugin.php

@@ -400,6 +400,7 @@ private function init_common_subscribers() {
 			'performance_hints_warmup_subscriber',
 			'performance_hints_admin_subscriber',
 			'lrc_frontend_subscriber',
+			'taxonomy_subscriber',
 		];
 
 		$host_type = HostResolver::get_host_service();

tests/Fixtures/inc/Engine/Cache/TaxonomySubscriber/disableCacheOnNotValidTaxonomyPages.php

@@ -0,0 +1,71 @@
+<?php
+
+return [
+	'test_data' => [
+		'testIsNotInCategoryPage' => [
+			'config' => [
+				'is_category' => false,
+			],
+			'can_cache' => true,
+		],
+		'testIsNotInTagPage' => [
+			'config' => [
+				'is_category' => false,
+				'is_tag' => false,
+			],
+			'can_cache' => true,
+		],
+		'testIsNotInTaxPage' => [
+			'config' => [
+				'is_category' => false,
+				'is_tag' => false,
+				'is_tax' => false,
+			],
+			'can_cache' => true,
+		],
+		'testValidTaxonomyPage' => [
+			'config' => [
+				'is_category' => true,
+				'is_tag' => false,
+				'is_tax' => false,
+				'current_term_id' => 1,
+				'current_term_link' => 'http://example.com/category/test1',
+				'current_page_url' => 'http://example.com/category/test1',
+			],
+			'can_cache' => true,
+		],
+		'testEmptyTermId' => [
+			'config' => [
+				'is_category' => true,
+				'is_tag' => false,
+				'is_tax' => false,
+				'current_term_id' => 0,
+				'current_term_link' => '',
+				'current_page_url' => 'http://example.com/category/test1',
+			],
+			'can_cache' => true,
+		],
+		'testNotValidTermLink' => [
+			'config' => [
+				'is_category' => true,
+				'is_tag' => false,
+				'is_tax' => false,
+				'current_term_id' => 0,
+				'current_term_link' => new WP_Error(),
+				'current_page_url' => 'http://example.com/category/test1',
+			],
+			'can_cache' => true,
+		],
+		'testNotValidTaxonomyPage' => [
+			'config' => [
+				'is_category' => true,
+				'is_tag' => false,
+				'is_tax' => false,
+				'current_term_id' => 1,
+				'current_term_link' => 'http://example.com/category/test1',
+				'current_page_url' => 'http://example.com/category/additional-query/test1',
+			],
+			'can_cache' => false,
+		],
+	],
+];

tests/Integration/ContentTrait.php

@@ -55,6 +55,9 @@ protected function setUpCategory( $args = [] ) {
 		$category = $this->factory->category->create_and_get( $args );
 		$this->go_to( "/?cat={$category->term_id}" );
 
+		global $wp;
+		$wp->request = "category/{$category->slug}";
+
 		$this->assertTrue( is_category() );
 
 		return $category;
@@ -71,6 +74,9 @@ protected function setUpTag( $args = [] ) {
 		$tag = $this->factory->term->create_and_get( $args );
 		$this->go_to( "/?tag={$tag->slug}" );
 
+		global $wp;
+		$wp->request = "tag/{$tag->slug}";
+
 		$this->assertTrue( is_tag() );
 
 		return $tag;
@@ -99,6 +105,9 @@ protected function setUpTax( $taxonomy = 'wptests_tax', $object_type = 'post', a
 
 		$this->go_to( "/?{$taxonomy}={$term->slug}" );
 
+		global $wp;
+		$wp->request = "{$taxonomy}/{$term->slug}";
+
 		$this->assertTrue( is_tax() );
 
 		return [

tests/Unit/inc/Engine/Cache/TaxonomySubscriber/disableCacheOnNotValidTaxonomyPages.php

@@ -0,0 +1,41 @@
+<?php
+
+namespace WP_Rocket\Tests\Unit\inc\Engine\Cache\TaxonomySubscriber;
+
+use Brain\Monkey\Functions;
+use WP_Rocket\Engine\Cache\TaxonomySubscriber;
+use WP_Rocket\Tests\Unit\TestCase;
+
+/**
+ * Test class covering \WP_Rocket\Engine\Cache\TaxonomySubscriber::disable_cache_on_not_valid_taxonomy_pages
+ *
+ * @uses \WP_Rocket\Engine\Cache\TaxonomySubscriber::is_not_valid_taxonomies_page
+ *
+ * @group Cache
+ */
+class Test_DisableCacheOnNotValidTaxonomyPages extends TestCase {
+	private $subscriber;
+
+	protected function setUp(): void {
+		parent::setUp();
+
+		$this->subscriber = new TaxonomySubscriber();
+	}
+
+
+	/**
+	 * @dataProvider configTestData
+	 */
+	public function testShouldReturnExpected( $config, $can_cache ) {
+		Functions\expect( 'is_category' )->once()->andReturn( ! empty( $config['is_category'] ) );
+		Functions\when( 'is_tag' )->justReturn( ! empty( $config['is_tag'] ) );
+		Functions\when( 'is_tax' )->justReturn( ! empty( $config['is_tax'] ) );
+		Functions\when( 'get_queried_object_id' )->justReturn( $config['current_term_id'] ?? 0 );
+
+		Functions\when( 'get_term_link' )->justReturn( $config['current_term_link'] ?? '' );
+		Functions\when( 'add_query_arg' )->justReturn( '' );
+		Functions\when( 'home_url' )->justReturn( $config['current_page_url'] ?? '' );
+
+		$this->assertSame( $can_cache, $this->subscriber->disable_cache_on_not_valid_taxonomy_pages( true ) );
+	}
+}