wordpress-develop/tests/phpunit/tests/option/userSettings.php

<?php
class Tests_User_Settings extends WP_UnitTestCase {
	protected $user_id;

	function setUp() {
		parent::setUp();

		$this->user_id = $this->factory->user->create( array(
			'role' => 'administrator'
		) );

		wp_set_current_user( $this->user_id );
	}

	function tearDown() {
		unset( $GLOBALS['_updated_user_settings'] );
		delete_user_option( $this->user_id, 'user-settings' );

		parent::tearDown();
	}

	function test_set_user_setting() {
		$foo = get_user_setting( 'foo' );

		$this->assertEmpty( $foo );

		$this->set_user_setting( 'foo', 'bar' );

		$this->assertEquals( 'bar', get_user_setting( 'foo' ) );
	}

	function test_set_user_setting_dashes() {
		$foo = get_user_setting( 'foo' );

		$this->assertEmpty( $foo );

		$this->set_user_setting( 'foo', 'foo-bar' );

		$this->assertEquals( 'foo-bar', get_user_setting( 'foo' ) );
	}

	// set_user_setting bails if `headers_sent()` is true
	function set_user_setting( $name, $value ) {
		$all_user_settings = get_all_user_settings();
		$all_user_settings[ $name ] = $value;

		return wp_set_all_user_settings( $all_user_settings );
	}
}