diff --git a/tests/phpunit/tests/admin/includes/plugin/deletePlugins.php b/tests/phpunit/tests/admin/includes/plugin/deletePlugins.php
new file mode 100644
index 0000000000000..577c822420e0b
--- /dev/null
+++ b/tests/phpunit/tests/admin/includes/plugin/deletePlugins.php
@@ -0,0 +1,315 @@
+<?php
+
+/**
+ * Tests for delete_plugins().
+ *
+ * @group admin
+ * @group plugins
+ *
+ * @covers ::delete_plugins
+ */
+class Tests_Admin_Includes_Plugin_DeletePlugins extends WP_UnitTestCase {
+
+	/**
+	 * Number used to give each test plugin a unique slug, since plugin files are included once.
+	 *
+	 * @var int
+	 */
+	private static $counter = 0;
+
+	/**
+	 * Uninstall callbacks that ran, by plugin file.
+	 *
+	 * @var string[]
+	 */
+	public static $uninstalled = array();
+
+	/**
+	 * The paths created by the current test, removed in tear_down() if they still exist.
+	 *
+	 * @var string[]
+	 */
+	private $created = array();
+
+	/**
+	 * Whether the wp_filesystem global was set before the test.
+	 *
+	 * @var bool
+	 */
+	private $had_filesystem;
+
+	/**
+	 * The original wp_filesystem global.
+	 *
+	 * @var mixed
+	 */
+	private $original_filesystem;
+
+	/**
+	 * Saves the filesystem global.
+	 */
+	public function set_up() {
+		parent::set_up();
+
+		$this->had_filesystem      = array_key_exists( 'wp_filesystem', $GLOBALS );
+		$this->original_filesystem = $this->had_filesystem ? $GLOBALS['wp_filesystem'] : null;
+
+		add_filter(
+			'filesystem_method',
+			static function () {
+				return 'direct';
+			}
+		);
+
+		self::$uninstalled = array();
+		delete_site_transient( 'update_plugins' );
+	}
+
+	/**
+	 * Removes what the test created and restores the filesystem global.
+	 */
+	public function tear_down() {
+		foreach ( array_reverse( $this->created ) as $path ) {
+			$this->remove_path( $path );
+		}
+
+		if ( $this->had_filesystem ) {
+			$GLOBALS['wp_filesystem'] = $this->original_filesystem;
+		} else {
+			unset( $GLOBALS['wp_filesystem'] );
+		}
+
+		wp_cache_delete( 'plugins', 'plugins' );
+		delete_site_transient( 'update_plugins' );
+
+		parent::tear_down();
+	}
+
+	/**
+	 * Tests that nothing is deleted without plugins.
+	 *
+	 * @ticket 65819
+	 *
+	 * @dataProvider data_no_plugins
+	 *
+	 * @param mixed $plugins The plugins to delete.
+	 */
+	public function test_should_return_false_without_plugins( $plugins ) {
+		$this->assertFalse( delete_plugins( $plugins ) );
+	}
+
+	/**
+	 * Data provider.
+	 *
+	 * @return array[]
+	 */
+	public static function data_no_plugins() {
+		return array(
+			'empty array' => array( array() ),
+			'null'        => array( null ),
+		);
+	}
+
+	/**
+	 * Tests that a plugin directory is deleted and the delete hooks fire.
+	 *
+	 * @ticket 65819
+	 */
+	public function test_should_delete_plugin_directory_and_fire_hooks() {
+		$plugin = $this->create_plugin_directory();
+
+		$delete  = new MockAction();
+		$deleted = new MockAction();
+		add_action( 'delete_plugin', array( $delete, 'action' ) );
+		add_action( 'deleted_plugin', array( $deleted, 'action' ), 10, 2 );
+
+		$this->assertTrue( delete_plugins( array( $plugin ) ), 'The plugin should be deleted.' );
+		$this->assertDirectoryDoesNotExist( WP_PLUGIN_DIR . '/' . dirname( $plugin ), 'The plugin directory should be removed.' );
+		$this->assertSame( array( array( $plugin ) ), $delete->get_args(), 'delete_plugin should receive the plugin.' );
+		$this->assertSame( array( array( $plugin, true ) ), $deleted->get_args(), 'deleted_plugin should receive the plugin and the result.' );
+	}
+
+	/**
+	 * Tests that only the file of a single-file plugin is deleted.
+	 *
+	 * @ticket 65819
+	 */
+	public function test_should_delete_only_file_of_single_file_plugin() {
+		$plugin = 'delete-test-single-' . ++self::$counter . '.php';
+		$this->create_file( WP_PLUGIN_DIR . '/' . $plugin, "<?php\n/**\n * Plugin Name: Single\n */\n" );
+
+		$this->assertTrue( delete_plugins( array( $plugin ) ), 'The plugin should be deleted.' );
+		$this->assertFileDoesNotExist( WP_PLUGIN_DIR . '/' . $plugin, 'The plugin file should be removed.' );
+		$this->assertFileExists( WP_PLUGIN_DIR . '/hello.php', 'Other plugins should be kept.' );
+	}
+
+	/**
+	 * Tests that the uninstall callback of a plugin runs before it is deleted.
+	 *
+	 * @ticket 65819
+	 */
+	public function test_should_run_uninstall_callback() {
+		$plugin = $this->create_plugin_directory();
+		update_option( 'uninstall_plugins', array( $plugin => array( __CLASS__, 'record_uninstall' ) ) );
+
+		$this->assertTrue( delete_plugins( array( $plugin ) ), 'The plugin should be deleted.' );
+		$this->assertSame( array( $plugin ), self::$uninstalled, 'The uninstall callback should run.' );
+	}
+
+	/**
+	 * Tests that deleted plugins are removed from the available updates.
+	 *
+	 * @ticket 65819
+	 */
+	public function test_should_remove_deleted_plugins_from_updates() {
+		$deleted = $this->create_plugin_directory();
+		$missing = $this->create_undeletable_plugin();
+
+		set_site_transient(
+			'update_plugins',
+			(object) array(
+				'response' => array(
+					$deleted          => (object) array( 'slug' => dirname( $deleted ) ),
+					$missing          => (object) array( 'slug' => 'missing-plugin' ),
+					'other/other.php' => (object) array( 'slug' => 'other' ),
+				),
+			)
+		);
+
+		delete_plugins( array( $deleted, $missing ) );
+
+		$this->assertSame( array( $missing, 'other/other.php' ), array_keys( get_site_transient( 'update_plugins' )->response ) );
+	}
+
+	/**
+	 * Tests that the translation files of a deleted plugin are removed.
+	 *
+	 * @ticket 65819
+	 */
+	public function test_should_delete_translation_files() {
+		$plugin = $this->create_plugin_directory();
+		$slug   = dirname( $plugin );
+		$dir    = WP_LANG_DIR . '/plugins/';
+
+		$po = "msgid \"\"\nmsgstr \"\"\n\"Project-Id-Version: Test\\n\"\n\"Language: de_DE\\n\"\n";
+		foreach ( array( '.po', '.mo', '.l10n.php', '-0123456789abcdef.json' ) as $suffix ) {
+			$this->create_file( "{$dir}{$slug}-de_DE{$suffix}", '.po' === $suffix ? $po : 'x' );
+		}
+
+		$this->assertTrue( delete_plugins( array( $plugin ) ), 'The plugin should be deleted.' );
+
+		foreach ( array( '.po', '.mo', '.l10n.php', '-0123456789abcdef.json' ) as $suffix ) {
+			$this->assertFileDoesNotExist( "{$dir}{$slug}-de_DE{$suffix}", "The {$suffix} translation file should be removed." );
+		}
+		$this->assertFileExists( $dir . 'internationalized-plugin-de_DE.mo', 'Translations of other plugins should be kept.' );
+	}
+
+	/**
+	 * Tests the error when a plugin cannot be removed.
+	 *
+	 * @ticket 65819
+	 */
+	public function test_should_report_plugin_that_could_not_be_removed() {
+		$plugin = $this->create_undeletable_plugin();
+
+		$deleted = new MockAction();
+		add_action( 'deleted_plugin', array( $deleted, 'action' ), 10, 2 );
+
+		$result = delete_plugins( array( $plugin ) );
+
+		$this->assertWPError( $result, 'An error should be returned.' );
+		$this->assertSame( 'could_not_remove_plugin', $result->get_error_code(), 'The error code should match.' );
+		$this->assertSame( "Could not fully remove the plugin {$plugin}.", $result->get_error_message(), 'The error message should name the plugin.' );
+		$this->assertSame( array( array( $plugin, false ) ), $deleted->get_args(), 'deleted_plugin should receive false.' );
+	}
+
+	/**
+	 * Tests the error when several plugins cannot be removed, while the others are deleted.
+	 *
+	 * @ticket 65819
+	 */
+	public function test_should_report_plugins_that_could_not_be_removed() {
+		$first  = $this->create_undeletable_plugin();
+		$plugin = $this->create_plugin_directory();
+		$second = $this->create_undeletable_plugin();
+
+		$result = delete_plugins( array( $first, $plugin, $second ) );
+
+		$this->assertWPError( $result, 'An error should be returned.' );
+		$this->assertSame( "Could not fully remove the plugins {$first}, {$second}.", $result->get_error_message(), 'The error message should list the plugins.' );
+		$this->assertDirectoryDoesNotExist( WP_PLUGIN_DIR . '/' . dirname( $plugin ), 'The other plugin should be deleted.' );
+	}
+
+	/**
+	 * Records that an uninstall callback ran.
+	 */
+	public static function record_uninstall() {
+		self::$uninstalled[] = current_action() ? substr( current_action(), strlen( 'uninstall_' ) ) : '';
+	}
+
+	/**
+	 * Creates a plugin directory with a main file and a second file.
+	 *
+	 * @return string The plugin file.
+	 */
+	private function create_plugin_directory() {
+		$slug = 'delete-test-plugin-' . ++self::$counter;
+		$dir  = WP_PLUGIN_DIR . '/' . $slug;
+
+		$this->remove_path( $dir );
+		$this->assertTrue( mkdir( $dir ), 'The test plugin directory should be created.' );
+		$this->created[] = $dir;
+
+		$this->create_file( "{$dir}/{$slug}.php", "<?php\n/**\n * Plugin Name: Delete Test Plugin\n */\n" );
+		$this->create_file( "{$dir}/readme.txt", 'Readme.' );
+
+		wp_cache_delete( 'plugins', 'plugins' );
+
+		return "{$slug}/{$slug}.php";
+	}
+
+	/**
+	 * Creates a single-file plugin that cannot be deleted: a directory with a file in it,
+	 * which a non-recursive delete cannot remove.
+	 *
+	 * @return string The plugin file.
+	 */
+	private function create_undeletable_plugin() {
+		$plugin = 'delete-test-undeletable-' . ++self::$counter . '.php';
+		$dir    = WP_PLUGIN_DIR . '/' . $plugin;
+
+		$this->remove_path( $dir );
+		$this->assertTrue( mkdir( $dir ), 'The test directory should be created.' );
+		$this->created[] = $dir;
+
+		$this->create_file( $dir . '/keep.txt', 'Keep.' );
+
+		return $plugin;
+	}
+
+	/**
+	 * Creates a file and registers it for cleanup.
+	 *
+	 * @param string $path     The file path.
+	 * @param string $contents The file contents.
+	 */
+	private function create_file( $path, $contents ) {
+		$this->remove_path( $path );
+		$this->assertNotFalse( file_put_contents( $path, $contents ), 'The file should be written.' );
+		$this->created[] = $path;
+	}
+
+	/**
+	 * Removes a file or directory, including one left over by an interrupted run.
+	 *
+	 * @param string $path The file or directory path.
+	 */
+	private function remove_path( $path ) {
+		if ( is_file( $path ) ) {
+			unlink( $path );
+		} elseif ( is_dir( $path ) ) {
+			$this->rmdir( $path );
+			$this->delete_folders( $path );
+		}
+	}
+}