public void ProviderDisposesChangeTokenRegistration()
        {
            var changeToken      = new ConfigurationRootTest.ChangeToken();
            var fileProviderMock = new Mock <IFileProvider>();

            fileProviderMock.Setup(fp => fp.Watch(It.IsAny <string>())).Returns(changeToken);

            var provider = new FileConfigurationProviderImpl(new FileConfigurationSourceImpl
            {
                FileProvider   = fileProviderMock.Object,
                ReloadOnChange = true,
            });

            Assert.NotEmpty(changeToken.Callbacks);

            provider.Dispose();

            Assert.Empty(changeToken.Callbacks);
        }