如何使用 C# 对登录到 log.net 进行单元测试

Question

I need to test if a message is correctly logged into log.net.

public bool load(string fileName) {
    if (File.Exists(fileName))
        return true;
    Logger.Error("file does not exist");
    return false;
}

In my test file, I have this:

[Test Class]
public FileTest {
    private File file;
    
    [TestInitialize]
    public void Setup() {
        file = new File();
    }

    [TestMethod]
    public void ConstructorSuccessedTest() {
        Assert.IsNotNull(file);
        Assert.IsNotNull(File.Logger);
    }
}

I need another test method to know whether the message in Logger.Error() is correctly logged into log.net.

I don't know where to start.

Answer 1

i found my answer:

[TestMethod]
public void LoggerIngo()
{
    var appender = new log4net.Appender.MemoryAppender();
    log4net.Config.BasicConfigurator.configure(appender);
    
    var fileLoad = file.load("file.xlsx");

    var logEntries = appender.GetEvents();
    Assert.AreEquals("file does not exist", logEntries[0].MessageObject.ToString());
}

Answer 2

I am not familiar with log.net, but I think you can use an interface for Logger.

If you add a Logger instance to the constructor, you are able to add a Mock of ILog. Just Assert that mock to check the messages.

private static readonly log4net.Ilog _logger;

public Cut (log4net.ILog logger){
    _logger = logger;
}

public bool load(string fileName) {
    if (File.Exists(fileName))
        return true;
    _logger.Error("file does not exist");
    return false;
}