通过ConfigurationManager使用.NET配置文件时,可以通过添加配置文件进行单元测试,虽然可以通过测试但达不到解耦的目的。使用IConfigurationManager和ConfigurationManagerWrapper对ConfigurationManager进行适配是更好的方式,ConfigurationManagerWrapper提供.NET配置文件方式的实现,如果需要支持其他配置,创建IConfigurationManager接口的不同的实现类即可。
原本依赖ConfigurationManager的代码现在依赖IConfigurationManager。可以在单元测试时方便的Mock。
public interface IConfigurationManager{ NameValueCollection AppSettings { get; } ConnectionStringSettingsCollection ConnectionStrings { get; } object GetSection(string sectionName);}
非单元测试环境使用ConfigurationManagerWrapper作为IConfigurationManager的默认实现。
public class ConfigurationManagerWrapper : IConfigurationManager{ public NameValueCollection AppSettings { get { return ConfigurationManager.AppSettings; } } public ConnectionStringSettingsCollection ConnectionStrings { get { return ConfigurationManager.ConnectionStrings; } } public object GetSection(string sectionName) { return ConfigurationManager.GetSection(sectionName); }}
在我们的代码需要使用配置时,可以考虑创建通用的泛型接口也可以使用专用的强类型的接口。这里演示使用通用的接口。
public interface IConfiguration{ T Get<T>(string key, T @default);}
AppConfigAdapter直接不使用ConfigurationManager而是依赖IConfigurationManager接口。
public class AppConfigAdapter : IConfiguration{ PRivate IConfigurationManager _configurationManager; public AppConfigAdapter(IConfigurationManager configurationManager) { this._configurationManager = configurationManager; } public T Get<T>(string nodeName, T @default) { var value = this._configurationManager.AppSettings[nodeName]; return value == null ? @default : (T)Convert.ChangeType(value, typeof(T)); }}
使用最流行的单元测试框架和Mock类库:xUnit+Moq进行单元测试。
public class AppConfigAdapterTest{ [Fact] public void GetStringTest() { var key = "key"; var value = "value"; var configuration = new AppConfigAdapter(this.GetConfigurationManager(o => o.Add(key, value.ToString()))); Assert.Equal(configuration.Get(key, string.Empty), value); } [Fact] public void GetIntTest() { var key = "key"; var value = 1; var configuration = new AppConfigAdapter(this.GetConfigurationManager(o => o.Add(key, value.ToString()))); Assert.Equal(configuration.Get(key, int.MinValue), value); } [Fact] public void GetBoolTest() { var key = "key"; var value = true; var configuration = new AppConfigAdapter(this.GetConfigurationManager(o => o.Add(key, value.ToString()))); Assert.Equal(configuration.Get(key, false), value); } [Fact] public void GetDateTimeTest() { var key = "key"; var value = DateTime.Parse(DateTime.Now.ToString()); var configuration = new AppConfigAdapter(this.GetConfigurationManager(o => o.Add(key, value.ToString()))); Assert.Equal(configuration.Get(key, DateTime.MinValue), value); } [Fact] public void GetDecimalTest() { var key = "key"; var value = 1.1m; var configuration = new AppConfigAdapter(this.GetConfigurationManager(o => o.Add(key, value.ToString()))); Assert.Equal(configuration.Get(key, decimal.MinValue), value); } private IConfigurationManager GetConfigurationManager(Action<NameValueCollection> set) { var appSettings = new NameValueCollection(); set(appSettings); var configurationManager = new Mock<IConfigurationManager>(); configurationManager.Setup(o => o.AppSettings).Returns(appSettings); return configurationManager.Object; }}
运行结果:
使依赖ConfigurationManager静态类的代码转换为依赖IConfigurationManager接口,运行时注入ConfigurationManagerWrapper实现类。单元测试时使用Mock模拟IConfigurationManager对象。
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