System.IO.Abstractions

庫的核心是IFileSystem和FileSystem 。而不是直接調用諸如File.ReadAllText之類的方法，而是使用IFileSystem.File.ReadAllText 。我們的API完全相同，除了我們的API是可注射且可測試的。

用法

dotnet add package TestableIO.System.IO.Abstractions.Wrappers

注意：此Nuget軟件包也以System.IO.Abstractions形式發布，但我們建議使用前綴清楚地表明這不是官方的.NET軟件包。

 public class MyComponent
{
    readonly IFileSystem fileSystem ;

    // <summary>Create MyComponent with the given fileSystem implementation</summary>
    public MyComponent ( IFileSystem fileSystem )
    {
        this . fileSystem = fileSystem ;
    }
    /// <summary>Create MyComponent</summary>
    public MyComponent ( ) : this (
        fileSystem : new FileSystem ( ) //use default implementation which calls System.IO
    )
    {
    }

    public void Validate ( )
    {
        foreach ( var textFile in fileSystem . Directory . GetFiles ( @"c:" , " *.txt " , SearchOption . TopDirectoryOnly ) )
        {
            var text = fileSystem . File . ReadAllText ( textFile ) ;
            if ( text != " Testing is awesome. " )
                throw new NotSupportedException ( " We can't go on together. It's not me, it's you. " ) ;
        }
    }
}

測試助手

圖書館還帶有一系列的測試幫助者，以使您不必嘲笑每個呼叫，以獲取基本情況。它們不是真實文件系統的完整副本，但是它們會大部分時間為您帶來。

dotnet add package TestableIO.System.IO.Abstractions.TestingHelpers

注意：此Nuget軟件包還以System.IO.Abstractions.TestingHelpers的形式發布，但我們建議使用前綴清楚地表明這不是官方的.NET軟件包。

 [ Test ]
public void MyComponent_Validate_ShouldThrowNotSupportedExceptionIfTestingIsNotAwesome ( )
{
    // Arrange
    var fileSystem = new MockFileSystem ( new Dictionary < string , MockFileData >
    {
        { @"c:myfile.txt" , new MockFileData ( " Testing is meh. " ) } ,
        { @"c:demojQuery.js" , new MockFileData ( " some js " ) } ,
        { @"c:demoimage.gif" , new MockFileData ( new byte [ ] { 0x12 , 0x34 , 0x56 , 0xd2 } ) }
    } ) ;
    var component = new MyComponent ( fileSystem ) ;

    try
    {
        // Act
        component . Validate ( ) ;
    }
    catch ( NotSupportedException ex )
    {
        // Assert
        Assert . That ( ex . Message , Is . EqualTo ( " We can't go on together. It's not me, it's you. " ) ) ;
        return ;
    }

    Assert . Fail ( " The expected exception was not thrown. " ) ;
}

我們甚至支持從.NET Framework的不可測試類型到我們可測試的包裝器的鑄造：

FileInfo SomeApiMethodThatReturnsFileInfo ( )
{
    return new FileInfo ( " a " ) ;
}

void MyFancyMethod ( )
{
    var testableFileInfo = ( FileInfoBase ) SomeApiMethodThatReturnsFileInfo ( ) ;
    .. .
}

模擬支持

由於版本4.0，頂級API揭示了接口而不是抽象基類（儘管仍然存在），從而使您可以完全模擬文件系統。這是一個很小的例子，使用量量：

 [ Test ]
public void Test1 ( )
{
    var watcher = Mock . Of < IFileSystemWatcher > ( ) ;
    var file = Mock . Of < IFile > ( ) ;

    Mock . Get ( file ) . Setup ( f => f . Exists ( It . IsAny < string > ( ) ) ) . Returns ( true ) ;
    Mock . Get ( file ) . Setup ( f => f . ReadAllText ( It . IsAny < string > ( ) ) ) . Throws < OutOfMemoryException > ( ) ;

    var unitUnderTest = new SomeClassUsingFileSystemWatcher ( watcher , file ) ;

    Assert . Throws < OutOfMemoryException > ( ( ) => {
        Mock . Get ( watcher ) . Raise ( w => w . Created += null , new System . IO . FileSystemEventArgs ( System . IO . WatcherChangeTypes . Created , @"C:SomeDirectory" , " Some.File " ) ) ;
    } ) ;

    Mock . Get ( file ) . Verify ( f => f . Exists ( It . IsAny < string > ( ) ) , Times . Once ) ;

    Assert . True ( unitUnderTest . FileWasCreated ) ;
}

public class SomeClassUsingFileSystemWatcher
{
    private readonly IFileSystemWatcher _watcher ;
    private readonly IFile _file ;

    public bool FileWasCreated { get ; private set ; }

    public SomeClassUsingFileSystemWatcher ( IFileSystemWatcher watcher , IFile file )
    {
        this . _file = file ;
        this . _watcher = watcher ;
        this . _watcher . Created += Watcher_Created ;
    }

    private void Watcher_Created ( object sender , System . IO . FileSystemEventArgs e )
    {
        FileWasCreated = true ;

        if ( _file . Exists ( e . FullPath ) )
        {
            var text = _file . ReadAllText ( e . FullPath ) ;
        }
    }
} 

相關項目

• System.IO.Abstractions.Extensions在核心抽象之上提供便利功能。

• System.IO.Abstractions.Analyzers提供了羅斯林分析儀，以幫助使用靜態方法的抽象。

• Testably.Abstractions提供替代的測試助手和其他抽象。