Question

I am trying to verify that certain errors are logged in log4net file and how many times.
I am working on following code which will read one value and assert if it is right, but
I want to see how many times it appeared in the log file than assert it if it is true.

private string logfile;

[SetUp]
public void SetUp()
{
    logfile = Path.Combine(
        Environment.GetEnvironmentVariable("ALLUSERSPROFILE"),
        "test.log");

    if (File.Exists(logfile))
        File.Delete(logfile);

    XmlConfigurator.Configure();
}

[Test] public void GivenLog4NetFileAppender_WhenLogInfoStringWithLog4Net_ThenWritesToDisk()
{
    ILog log = LogManager.GetLogger(typeof (LoggingIntegrationTests));
    log.Info("Error 2");

    LogManager.Shutdown();

    Assert.That(File.ReadAllText(logfile),
                Is.StringContaining("Error 2"));
}

So in above code if Error 2 is logged 3 times than I want to assert that it appeared 3 times.
Thanks for you help

Answer 1

You could use a Regex to count the number of times a given string occurs within another string:

[Test] 
public void GivenLog4NetFileAppender_WhenLogInfoStringWithLog4Net_ThenWritesToDisk()
{
    // arrange
    ILog log = LogManager.GetLogger(typeof (LoggingIntegrationTests));
    string  = "Error 2";

    // act
    log.Info(dataToLog);

    // assert
    LogManager.Shutdown();
    var matches = Regex.Matches(File.ReadAllText(logfile), dataToLog);
    Assert.AreEqual(3, matches.Count);
}