public async Task KeyVaultKeyCache_Success()
        {
            var services = DiHelper.GetServiceProviderKeyCache <AcmeKeyVaultCache>();

            var key           = KeyFactory.NewKey(KeyAlgorithm.ES256);
            var cacheProvider = services.GetService <IAcmeKeyCache>();

            await cacheProvider.SaveAccountKey(key);

            var key2 = await cacheProvider.GetAccountKey();

            Assert.Equal(key.ToPem(), key2.ToPem());
        }