public function testTestUserExists()
 {
     $plugin = $this->getMock('AuthPlugin');
     $plugin->expects($this->any())->method('domainList')->willReturn([]);
     $plugin->expects($this->once())->method('userExists')->with($this->equalTo('Foo'))->will($this->returnValue(true));
     $provider = new AuthPluginPrimaryAuthenticationProvider($plugin);
     $this->assertTrue($provider->testUserExists('foo'));
     $plugin = $this->getMock('AuthPlugin');
     $plugin->expects($this->any())->method('domainList')->willReturn([]);
     $plugin->expects($this->once())->method('userExists')->with($this->equalTo('Foo'))->will($this->returnValue(false));
     $provider = new AuthPluginPrimaryAuthenticationProvider($plugin);
     $this->assertFalse($provider->testUserExists('foo'));
 }