diff --git a/composer.json b/composer.json
index 1ba1f207b..df669a663 100644
--- a/composer.json
+++ b/composer.json
@@ -18,7 +18,7 @@
         "wp-cli/db-command": "^1.3 || ^2",
         "wp-cli/entity-command": "^1.3 || ^2",
         "wp-cli/extension-command": "^1.2 || ^2",
-        "wp-cli/wp-cli-tests": "^3.1"
+        "wp-cli/wp-cli-tests": "^4"
     },
     "config": {
         "process-timeout": 7200,
diff --git a/language-command.php b/language-command.php
index 5153b90ea..02c0a5b77 100644
--- a/language-command.php
+++ b/language-command.php
@@ -4,13 +4,13 @@
 	return;
 }
 
-$wpcli_language_autoloader = dirname( __FILE__ ) . '/vendor/autoload.php';
+$wpcli_language_autoloader = __DIR__ . '/vendor/autoload.php';
 
 if ( file_exists( $wpcli_language_autoloader ) ) {
 	require_once $wpcli_language_autoloader;
 }
 
-$wpcli_language_check_requirements = function() {
+$wpcli_language_check_requirements = function () {
 	if ( \WP_CLI\Utils\wp_version_compare( '4.0', '<' ) ) {
 		WP_CLI::error( 'Requires WordPress 4.0 or greater.' );
 	}
diff --git a/phpcs.xml.dist b/phpcs.xml.dist
index 6f1bc3e21..0dd741bd0 100644
--- a/phpcs.xml.dist
+++ b/phpcs.xml.dist
@@ -63,7 +63,7 @@
 		 Related: https://github.com/WordPress-Coding-Standards/WordPress-Coding-Standards/issues/1623 -->
 	<rule ref="WordPress.NamingConventions.ValidVariableName">
 		<properties>
-			<property name="customPropertiesWhitelist" type="array">
+			<property name="allowed_custom_properties" type="array">
 				<element value="Language"/>
 				<element value="Name"/>
 				<element value="Type"/>
diff --git a/src/Core_Language_Command.php b/src/Core_Language_Command.php
index b6a6271b5..8430bc536 100644
--- a/src/Core_Language_Command.php
+++ b/src/Core_Language_Command.php
@@ -93,7 +93,7 @@ public function list_( $args, $assoc_args ) {
 		$current_locale = get_locale();
 
 		$translations = array_map(
-			function( $translation ) use ( $available, $current_locale, $updates ) {
+			function ( $translation ) use ( $available, $current_locale, $updates ) {
 				$translation['status'] = 'uninstalled';
 				if ( in_array( $translation['language'], $available, true ) ) {
 					$translation['status'] = 'installed';
@@ -199,7 +199,7 @@ public function install( $args, $assoc_args ) {
 
 			if ( in_array( $language_code, $available, true ) ) {
 				\WP_CLI::log( "Language '{$language_code}' already installed." );
-				$skips++;
+				++$skips;
 			} else {
 				$response = $this->download_language_pack( $language_code );
 
@@ -209,13 +209,13 @@ public function install( $args, $assoc_args ) {
 
 					// Skip if translation is not yet available.
 					if ( 'not_found' === $response->get_error_code() ) {
-						$skips++;
+						++$skips;
 					} else {
-						$errors++;
+						++$errors;
 					}
 				} else {
 					\WP_CLI::log( "Language '{$language_code}' installed." );
-					$successes++;
+					++$successes;
 				}
 			}
 
diff --git a/src/Plugin_Language_Command.php b/src/Plugin_Language_Command.php
index 681514ed7..2a59c59a9 100644
--- a/src/Plugin_Language_Command.php
+++ b/src/Plugin_Language_Command.php
@@ -263,7 +263,7 @@ private function install_one( $args, $assoc_args ) {
 
 			if ( in_array( $language_code, $available, true ) ) {
 				\WP_CLI::log( "Language '{$language_code}' already installed." );
-				$skips++;
+				++$skips;
 			} else {
 				$response = $this->download_language_pack( $language_code, $plugin );
 
@@ -273,13 +273,13 @@ private function install_one( $args, $assoc_args ) {
 
 					// Skip if translation is not yet available.
 					if ( 'not_found' === $response->get_error_code() ) {
-						$skips++;
+						++$skips;
 					} else {
-						$errors++;
+						++$errors;
 					}
 				} else {
 					\WP_CLI::log( "Language '{$language_code}' installed." );
-					$successes++;
+					++$successes;
 				}
 			}
 		}
@@ -332,7 +332,7 @@ private function install_many( $args, $assoc_args ) {
 				if ( in_array( $language_code, $available, true ) ) {
 					\WP_CLI::log( "Language '{$language_code}' for '{$plugin_details['Name']}' already installed." );
 					$result['status'] = 'already installed';
-					$skips++;
+					++$skips;
 				} else {
 					$response = $this->download_language_pack( $language_code, $plugin_name );
 
@@ -342,15 +342,15 @@ private function install_many( $args, $assoc_args ) {
 
 						if ( 'not_found' === $response->get_error_code() ) {
 							$result['status'] = 'not available';
-							$skips++;
+							++$skips;
 						} else {
 							$result['status'] = 'not installed';
-							$errors++;
+							++$errors;
 						}
 					} else {
 						\WP_CLI::log( "Language '{$language_code}' for '{$plugin_details['Name']}' installed." );
 						$result['status'] = 'installed';
-						$successes++;
+						++$successes;
 					}
 				}
 
diff --git a/src/Theme_Language_Command.php b/src/Theme_Language_Command.php
index 6765e2052..5bcdc6e69 100644
--- a/src/Theme_Language_Command.php
+++ b/src/Theme_Language_Command.php
@@ -98,7 +98,7 @@ public function list_( $args, $assoc_args ) {
 
 		if ( $all ) {
 			$args = array_map(
-				function( $file ) {
+				function ( $file ) {
 					return \WP_CLI\Utils\get_theme_name( $file );
 				},
 				array_keys( wp_get_themes() )
@@ -269,7 +269,7 @@ private function install_one( $args, $assoc_args ) {
 
 			if ( in_array( $language_code, $available, true ) ) {
 				\WP_CLI::log( "Language '{$language_code}' already installed." );
-				$skips++;
+				++$skips;
 			} else {
 				$response = $this->download_language_pack( $language_code, $theme );
 
@@ -279,13 +279,13 @@ private function install_one( $args, $assoc_args ) {
 
 					// Skip if translation is not yet available.
 					if ( 'not_found' === $response->get_error_code() ) {
-						$skips++;
+						++$skips;
 					} else {
-						$errors++;
+						++$errors;
 					}
 				} else {
 					\WP_CLI::log( "Language '{$language_code}' installed." );
-					$successes++;
+					++$successes;
 				}
 			}
 		}
@@ -338,7 +338,7 @@ private function install_many( $args, $assoc_args ) {
 				if ( in_array( $language_code, $available, true ) ) {
 					\WP_CLI::log( "Language '{$language_code}' for '{$theme_details['Name']}' already installed." );
 					$result['status'] = 'already installed';
-					$skips++;
+					++$skips;
 				} else {
 					$response = $this->download_language_pack( $language_code, $theme_name );
 
@@ -348,15 +348,15 @@ private function install_many( $args, $assoc_args ) {
 
 						if ( 'not_found' === $response->get_error_code() ) {
 							$result['status'] = 'not available';
-							$skips++;
+							++$skips;
 						} else {
 							$result['status'] = 'not installed';
-							$errors++;
+							++$errors;
 						}
 					} else {
 						\WP_CLI::log( "Language '{$language_code}' for '{$theme_details['Name']}' installed." );
 						$result['status'] = 'installed';
-						$successes++;
+						++$successes;
 					}
 				}
 
diff --git a/src/WP_CLI/CommandWithTranslation.php b/src/WP_CLI/CommandWithTranslation.php
index a07dab0f7..1cfcdd331 100644
--- a/src/WP_CLI/CommandWithTranslation.php
+++ b/src/WP_CLI/CommandWithTranslation.php
@@ -144,7 +144,7 @@ public function update( $args, $assoc_args ) {
 	protected function get_translation_updates() {
 		$available = $this->get_installed_languages();
 
-		$func = function() use ( $available ) {
+		$func = function () use ( $available ) {
 			return $available;
 		};