public TenantAppConfigurationSection(IAppConfigurationRoot root, string key, string tenant)
        {
            if (string.IsNullOrEmpty(tenant))
            {
                throw new ArgumentException("Cannot be null or empty.", nameof(tenant));
            }

            this.root   = root;
            this.tenant = tenant;

            string tenantKey, globalKey;

            if (tenant == key)
            {
                tenantKey = tenant;
                globalKey = null;
            }
            else if (key.StartsWith($"{tenant}{AppConfigurationPath.KeyDelimiter}", StringComparison.OrdinalIgnoreCase))
            {
                tenantKey = key;
                globalKey = key.Substring(tenant.Length + 1);
            }
            else
            {
                tenantKey = AppConfigurationPath.Combine(tenant, key);
                globalKey = key;
            }

            tenantSection = root.GetSection(tenantKey);
            globalSection = globalKey == null ? null : root.GetSection(globalKey);

            Path  = tenantKey;
            Value = tenantSection.Exists() ? tenantSection.Value : globalSection?.Value;
        }
        public void GetSection_WithNotPresentSection_ReturnsEmptySection()
        {
            var configManager = new ConfigurationManagerFixture()
                                .WithAppSetting("Section:Key", "Value1")
                                .Build();

            var appConfig = new AppConfiguration(configManager);

            IAppConfigurationSection section = appConfig.GetSection("SectionNotPresent");

            bool actual = section.Exists();

            Assert.That(actual, Is.False);
        }