Tests: Add coverage for wp_roles().

Verify initialization, reuse of an existing `WP_Roles` instance, and replacement of invalid global values. Cover the behavior introduced in [63490].

Developed in: #14257

Props huzaifaalmesbah.
See #65819.


git-svn-id: https://develop.svn.wordpress.org/trunk@64360 602fd350-edb4-49c9-b593-d223f7449a82

Author: lancewillett

tests/phpunit/tests/user/wpRoles.php

@@ -0,0 +1,95 @@
+<?php
+
+/**
+ * Tests for wp_roles().
+ *
+ * @group user
+ * @group capabilities
+ *
+ * @covers ::wp_roles
+ */
+class Tests_User_wpRoles extends WP_UnitTestCase {
+
+	/**
+	 * Original roles object.
+	 *
+	 * @var WP_Roles|null
+	 */
+	private $original_wp_roles;
+
+	public function set_up() {
+		parent::set_up();
+
+		$this->original_wp_roles = $GLOBALS['wp_roles'] ?? null;
+	}
+
+	public function tear_down() {
+		$GLOBALS['wp_roles'] = $this->original_wp_roles;
+
+		parent::tear_down();
+	}
+
+	/**
+	 * Tests that the roles object is instantiated when the global is not set.
+	 *
+	 * @ticket 65819
+	 */
+	public function test_should_instantiate_roles_when_global_is_not_set() {
+		unset( $GLOBALS['wp_roles'] );
+
+		$roles = wp_roles();
+
+		$this->assertInstanceOf( WP_Roles::class, $roles, 'A WP_Roles instance should be returned.' );
+		$this->assertSame( $roles, $GLOBALS['wp_roles'], 'The instance should be stored in the global.' );
+	}
+
+	/**
+	 * Tests that an existing roles object is returned as is.
+	 *
+	 * @ticket 65819
+	 */
+	public function test_should_return_existing_roles_instance() {
+		$roles               = new WP_Roles();
+		$GLOBALS['wp_roles'] = $roles;
+
+		$this->assertSame( $roles, wp_roles(), 'The existing instance should be returned.' );
+		$this->assertSame( $roles, $GLOBALS['wp_roles'], 'The global should not be replaced.' );
+	}
+
+	/**
+	 * Tests that a global which is not a roles object is replaced.
+	 *
+	 * @ticket 65819
+	 *
+	 * @dataProvider data_values_other_than_roles_instance
+	 *
+	 * @param mixed $value Value the global was overwritten with.
+	 */
+	public function test_should_replace_global_which_is_not_roles_instance( $value ) {
+		$GLOBALS['wp_roles'] = $value;
+
+		$roles = wp_roles();
+
+		$this->assertInstanceOf( WP_Roles::class, $roles, 'A WP_Roles instance should be returned.' );
+		$this->assertSame( $roles, $GLOBALS['wp_roles'], 'The instance should be stored in the global.' );
+	}
+
+	/**
+	 * Data provider.
+	 *
+	 * @return array[]
+	 */
+	public static function data_values_other_than_roles_instance() {
+		return array(
+			'null'            => array( null ),
+			'false'           => array( false ),
+			'true'            => array( true ),
+			'zero'            => array( 0 ),
+			'an empty string' => array( '' ),
+			'a role name'     => array( 'administrator' ),
+			'an empty array'  => array( array() ),
+			'an array'        => array( array( 'administrator' => array() ) ),
+			'another object'  => array( new stdClass() ),
+		);
+	}
+}