Reuse plugins and themes downloaded from WordPress.org across scenarios

composer.json

@@ -32,6 +32,9 @@
         "wp-coding-standards/wpcs": "dev-develop",
         "yoast/phpunit-polyfills": "^2.0 || ^3.0 || ^4.0"
     },
+    "require-dev": {
+        "wp-cli/extension-command": "^1 || ^2 || ^3"
+    },
     "config": {
         "allow-plugins": {
             "dealerdirect/phpcodesniffer-composer-installer": true,

features/behat-steps.feature

@@ -468,6 +468,80 @@ Feature: Test that WP-CLI Behat steps work as expected
     When I launch in the background `wp eval 'sleep(2); echo "done";'`
     # Background process should not block, continuing immediately
 
+  @require-wp
+  Scenario: Install plugins and themes from WordPress.org
+    Given a WP installation
+    And these installed themes:
+      """
+      twentysixteen
+      """
+    And these installed and active plugins:
+      """
+      wordpress-importer --version=0.8
+      """
+    Then the wp-content/themes/twentysixteen/style.css file should exist
+
+    When I run `wp plugin get wordpress-importer --fields=status,version --format=csv`
+    Then STDOUT should contain:
+      """
+      status,active
+      version,0.8
+      """
+
+  @require-wp
+  Scenario: Install cached plugins and themes without requests to WordPress.org
+    Given a WP installation
+    And these installed themes:
+      """
+      twentysixteen
+      oceanly-green
+      """
+    And these installed plugins:
+      """
+      wordpress-importer --version=0.8
+      """
+    And a non-existent wp-content/themes/twentysixteen directory
+    And a non-existent wp-content/themes/oceanly-green directory
+    And a non-existent wp-content/themes/oceanly directory
+    And a non-existent wp-content/plugins/wordpress-importer directory
+    And a wp-content/mu-plugins/block-http-requests.php file:
+      """
+      <?php
+      add_filter(
+          'pre_http_request',
+          static function () {
+              return new WP_Error( 'http_request_blocked', 'HTTP requests are blocked.' );
+          }
+      );
+      """
+
+    When these installed themes:
+      """
+      oceanly-green
+      """
+    And these installed and active themes:
+      """
+      twentysixteen
+      """
+    And these installed and active plugins:
+      """
+      wordpress-importer --version=0.8
+      """
+    And I run `wp theme list --status=active --field=name`
+    Then STDOUT should be:
+      """
+      twentysixteen
+      """
+
+    When I run `wp plugin get wordpress-importer --fields=status,version --format=csv`
+    Then STDOUT should contain:
+      """
+      status,active
+      version,0.8
+      """
+    And the wp-content/themes/oceanly-green/style.css file should exist
+    And the wp-content/themes/oceanly/style.css file should exist
+
   @require-wp
   Scenario: Test custom wp-content directory
     Given a WP installation

src/Context/FeatureContext.php

@@ -1871,6 +1871,136 @@ public function download_wp( $subdir = '', $version = '' ): void {
 		}
 	}
 
+	/**
+	 * Install plugins or themes, copying the ones from WordPress.org from a local cache when possible.
+	 *
+	 * @param string        $type     Either 'plugin' or 'theme'.
+	 * @param array<string> $lines    Slugs, optionally followed by `--version=<version>` and `--force`, or anything `wp plugin install` accepts.
+	 * @param bool          $activate Whether to activate them.
+	 */
+	public function install_extensions( $type, array $lines, $activate ): void {
+		$target_dir = $this->get_extension_dir( $type );
+		$slugs      = [];
+		$uncached   = [];
+		$others     = [];
+
+		foreach ( $lines as $line ) {
+			if ( ! preg_match( '/^([a-z0-9][a-z0-9._-]*)(?:\s+--version=(\S+))?(\s+--force)?$/i', $line, $matches ) || null === $target_dir ) {
+				$others[] = $line;
+				continue;
+			}
+
+			$slug    = $matches[1];
+			$flags   = ( isset( $matches[2] ) && '' !== $matches[2] ? ' --version=' . escapeshellarg( $matches[2] ) : '' ) . ( empty( $matches[3] ) ? '' : ' --force' );
+			$slugs[] = $slug;
+
+			$cache_path = self::get_extension_cache_path( $type, $slug, $flags );
+			if ( is_dir( $cache_path ) ) {
+				self::remove_dir( "$target_dir/$slug" );
+				mkdir( "$target_dir/$slug" );
+				self::copy_dir( $cache_path, "$target_dir/$slug" );
+
+				// Installing a child theme also installs its parent.
+				$parent = 'theme' === $type ? self::get_parent_theme( "$target_dir/$slug" ) : '';
+				if ( '' !== $parent && ! is_dir( "$target_dir/$parent" ) ) {
+					$this->install_extensions( 'theme', [ $parent ], false );
+				}
+			} else {
+				$uncached[ $flags ][] = $slug;
+			}
+		}
+
+		foreach ( $uncached as $flags => $uncached_slugs ) {
+			$this->proc( "wp $type install " . implode( ' ', array_map( 'escapeshellarg', $uncached_slugs ) ) . $flags )->run_check();
+
+			foreach ( $uncached_slugs as $slug ) {
+				if ( is_dir( "$target_dir/$slug" ) ) {
+					self::store_in_extension_cache( "$target_dir/$slug", self::get_extension_cache_path( $type, $slug, (string) $flags ) );
+				}
+
+				$parent = 'theme' === $type && is_dir( "$target_dir/$slug" ) ? self::get_parent_theme( "$target_dir/$slug" ) : '';
+				if ( '' !== $parent && is_dir( "$target_dir/$parent" ) && ! is_dir( self::get_extension_cache_path( 'theme', $parent, '' ) ) ) {
+					self::store_in_extension_cache( "$target_dir/$parent", self::get_extension_cache_path( 'theme', $parent, '' ) );
+				}
+			}
+		}
+
+		if ( $others ) {
+			$this->proc( "wp $type install " . implode( ' ', $others ) . ( $activate ? ' --activate' : '' ) )->run_check();
+		}
+
+		if ( $activate && $slugs ) {
+			$this->proc( "wp $type activate " . implode( ' ', array_map( 'escapeshellarg', $slugs ) ) )->run_check();
+		}
+	}
+
+	/**
+	 * Get the directory plugins or themes are installed into, or null if it is not known.
+	 *
+	 * @param string $type Either 'plugin' or 'theme'.
+	 */
+	private function get_extension_dir( $type ): ?string {
+		if ( ! isset( $this->variables['RUN_DIR'] ) ) {
+			return null;
+		}
+
+		$run_dir    = $this->variables['RUN_DIR'];
+		$candidates = 'plugin' === $type
+			? [ "$run_dir/my-plugins", "$run_dir/wp-content/plugins", "$run_dir/WordPress/wp-content/plugins" ]
+			: [ "$run_dir/my-content/themes", "$run_dir/wp-content/themes", "$run_dir/WordPress/wp-content/themes" ];
+
+		foreach ( $candidates as $candidate ) {
+			if ( is_dir( $candidate ) ) {
+				return $candidate;
+			}
+		}
+
+		return null;
+	}
+
+	/**
+	 * Get the parent of a theme from the `Template` header of its stylesheet, or '' if it has none.
+	 *
+	 * @param string $theme_dir
+	 */
+	private static function get_parent_theme( $theme_dir ): string {
+		$stylesheet = "$theme_dir/style.css";
+		if ( ! is_file( $stylesheet ) ) {
+			return '';
+		}
+
+		$header = (string) file_get_contents( $stylesheet, false, null, 0, 8192 );
+
+		return preg_match( '/^[ \t\/*#@]*Template:(.*)$/mi', $header, $matches ) ? trim( $matches[1] ) : '';
+	}
+
+	/**
+	 * @param string $type
+	 * @param string $slug
+	 * @param string $flags Install flags that change what gets installed.
+	 */
+	private static function get_extension_cache_path( $type, $slug, $flags ): string {
+		$key = implode( ':', [ $type, $slug, $flags, (string) getenv( 'WP_VERSION' ), PHP_MAJOR_VERSION . '.' . PHP_MINOR_VERSION ] );
+
+		return sys_get_temp_dir() . '/wp-cli-test-extension-cache/' . $type . '-' . $slug . '-' . substr( md5( $key ), 0, 12 );
+	}
+
+	/**
+	 * @param string $source_dir
+	 * @param string $cache_path
+	 */
+	private static function store_in_extension_cache( $source_dir, $cache_path ): void {
+		$temp_path = $cache_path . '-' . uniqid( '', true );
+		mkdir( $temp_path, 0777, true );
+
+		self::copy_dir( $source_dir, $temp_path );
+
+		// Another process may have filled the cache in the meantime.
+		if ( is_dir( $cache_path ) || ! rename( $temp_path, $cache_path ) ) {
+			self::remove_dir( $temp_path );
+		}
+	}
+
 	/**
 	 * Create a wp-config.php file.
 	 *

src/Context/GivenStepDefinitions.php

@@ -405,7 +405,12 @@ public function given_a_wp_multisite_installation( $type = 'subdirectory' ): voi
 	}
 
 	/**
-	 * Installs and activates one or more plugins.
+	 * Installs and optionally activates one or more plugins or themes.
+	 *
+	 * Plugins and themes from WordPress.org are downloaded once and copied from a local cache
+	 * afterwards. Each line holds a slug, optionally followed by `--version=<version>` and `--force`. Other
+	 * lines, like a URL or a path to a ZIP file, are installed with `wp plugin install` or
+	 * `wp theme install` every time.
 	 *
 	 * ```
 	 * Scenario: My example scenario
@@ -415,19 +420,30 @@ public function given_a_wp_multisite_installation( $type = 'subdirectory' ): voi
 	 *     akismet
 	 *     wordpress-importer
 	 *     """
+	 *
+	 * Scenario: My other scenario
+	 *   Given a WP installation
+	 *   And these installed themes:
+	 *     """
+	 *     twentysixteen
+	 *     twentyseventeen --version=1.0
+	 *     """
 	 * ```
 	 *
 	 * @access public
 	 *
-	 * @Given these installed and active plugins:
+	 * @Given /^these installed (and active )?(plugins|themes):$/
 	 *
-	 * @param string $stream
+	 * @param string       $active
+	 * @param string       $type
+	 * @param PyStringNode $stream
 	 */
-	public function given_these_installed_and_active_plugins( $stream ): void {
-		$plugins = implode( ' ', array_map( 'trim', explode( PHP_EOL, (string) $stream ) ) );
-		$plugins = $this->replace_variables( $plugins );
+	public function given_these_installed_plugins_or_themes( $active, $type, PyStringNode $stream ): void {
+		$lines    = array_filter( array_map( 'trim', explode( "\n", $this->replace_variables( (string) $stream ) ) ) );
+		$type     = 'plugins' === $type ? 'plugin' : 'theme';
+		$activate = '' !== trim( $active );
 
-		$this->proc( "wp plugin install $plugins --activate" )->run_check();
+		$this->install_extensions( $type, $lines, $activate );
 	}
 
 	/**