public async Task RaiseChangeEventAfterProviderSetToNull()
{
var testFileProvider = new TestFileProvider(
new TestFile("Secret1", "SecretValue1"),
new TestFile("Secret2", "SecretValue2"));
var configurationSource = new KeyPerFileConfigurationSource
{
FileProvider = testFileProvider,
Optional = true,
};
var keyPerFileProvider = new KeyPerFileConfigurationProvider(configurationSource);
var config = new ConfigurationRoot(new[] { keyPerFileProvider });
var changeToken = config.GetReloadToken();
var changeTaskCompletion = new TaskCompletionSource <object>();
changeToken.RegisterChangeCallback(state =>
((TaskCompletionSource <object>)state).TrySetResult(null), changeTaskCompletion);
configurationSource.FileProvider = null;
config.Reload();
await changeTaskCompletion.Task;
Assert.Empty(config.AsEnumerable());
}