public async Task EnvironmentVariableProviderAsyncTest()
        {
            EnvironmentVariableCredentialsProvider provider = new EnvironmentVariableCredentialsProvider();
            string tempClientType                 = AuthUtils.ClientType;
            string tempEnvironmentAccessKeyId     = AuthUtils.EnvironmentAccessKeyId;
            string tempEnvironmentAccesskeySecret = AuthUtils.EnvironmentAccesskeySecret;

            AuthUtils.ClientType = string.Empty;
            Assert.Null(await provider.GetCredentialsAsync());

            AuthUtils.ClientType             = "default";
            AuthUtils.EnvironmentAccessKeyId = null;
            Assert.Null(await provider.GetCredentialsAsync());

            AuthUtils.EnvironmentAccesskeySecret = null;
            Assert.Null(await provider.GetCredentialsAsync());

            AuthUtils.EnvironmentAccessKeyId     = string.Empty;
            AuthUtils.EnvironmentAccesskeySecret = string.Empty;
            await Assert.ThrowsAsync <CredentialException>(async() => { await provider.GetCredentialsAsync(); });

            AuthUtils.EnvironmentAccessKeyId = "AccessKeyId";
            await Assert.ThrowsAsync <CredentialException>(async() => { await provider.GetCredentialsAsync(); });

            AuthUtils.EnvironmentAccesskeySecret = "AccesskeySecret";
            Assert.IsType <AccessKeyCredential>(await provider.GetCredentialsAsync());

            AuthUtils.ClientType                 = tempClientType;
            AuthUtils.EnvironmentAccessKeyId     = tempEnvironmentAccessKeyId;
            AuthUtils.EnvironmentAccesskeySecret = tempEnvironmentAccesskeySecret;
        }
        public void EnvironmentVariableProviderTest()
        {
            EnvironmentVariableCredentialsProvider provider = new EnvironmentVariableCredentialsProvider();
            string tempClientType                 = AuthUtils.ClientType;
            string tempEnvironmentAccessKeyId     = AuthUtils.EnvironmentAccessKeyId;
            string tempEnvironmentAccesskeySecret = AuthUtils.EnvironmentAccesskeySecret;

            AuthUtils.ClientType = string.Empty;
            Assert.Null(provider.GetCredentials());

            AuthUtils.ClientType             = "default";
            AuthUtils.EnvironmentAccessKeyId = null;
            Assert.Null(provider.GetCredentials());

            AuthUtils.EnvironmentAccesskeySecret = null;
            Assert.Null(provider.GetCredentials());

            AuthUtils.EnvironmentAccessKeyId     = string.Empty;
            AuthUtils.EnvironmentAccesskeySecret = string.Empty;
            Assert.Throws <CredentialException>(() => { provider.GetCredentials(); });

            AuthUtils.EnvironmentAccessKeyId = "AccessKeyId";
            Assert.Throws <CredentialException>(() => { provider.GetCredentials(); });

            AuthUtils.EnvironmentAccesskeySecret = "AccesskeySecret";
            Assert.IsType <AccessKeyCredential>(provider.GetCredentials());

            AuthUtils.ClientType                 = tempClientType;
            AuthUtils.EnvironmentAccessKeyId     = tempEnvironmentAccessKeyId;
            AuthUtils.EnvironmentAccesskeySecret = tempEnvironmentAccesskeySecret;
        }