March 2009 – Lars Corneliussen

While writing tons of tests I would like to share some of my helper classes here. My first ones are for doing simple performance measurements (not too accurate) and repeating actions.

Code:

using (new Scenario("Sum of all squares from 1 to 100"))
    Console.WriteLine("Sum is: {0}", 100.Times(x => x * x).Sum());

using (new Scenario("Print all squares from 1 to 10"))
    10.Times(x => Console.WriteLine("{0} * {0} = {1}", x, x*x));

Output:

>> {1} - Sum of all squares from 1 to 100
Sum is: 1000000
<< {1} 15ms for Sum of all squares from 1 to 100
>> {2} - Print all squares from 1 to 10
1 * 1 = 1
2 * 2 = 4
3 * 3 = 9
4 * 4 = 16
5 * 5 = 25
6 * 6 = 36
7 * 7 = 49
8 * 8 = 64
9 * 9 = 81
10 * 10 = 100
<< {2} 13ms for Print all squares from 1 to 10
&#91;/sourcecode&#93;</pre></div>

<h2>Repetition Extensions</h2>

<div style="display:inline;float:none;margin:0;padding:0;" id="scid:4CF65DF0-5960-450c-B43D-AE27EAE72175:64baee98-e9e4-4a96-9dc8-a453ac2997da" class="wlWriterEditableSmartContent"><pre>
public static class RepetitionExtensions
{
    public static IEnumerable<int> Times(this int count)
    {
        for (int i = 1; i <= count; i++)
        {
            yield return i;
        }
    }

    public static void Times(this int count, Action<int> action)
    {
        foreach (var i in count.Times())
        {
            action(i);
        }
    }

    public static void Times(this int count, Action action)
    {
        count.Times((i) => action());
    }

    public static TResult[] Times<TResult>(this int count, Func<TResult> action)
    {
        var results = new List<TResult>(count);
        count.Times(() => results.Add(action()));
        return results.ToArray();
    }

    public static TResult[] Times<TResult>(this int count, Func<int, TResult> action)
    {
        var results = new List<TResult>(count);
        count.Times(() => results.Add(action(count)));
        return results.ToArray();
    }

    public static IEnumerable<TResult> LazyTimes<TResult>(this int count, Func<TResult> action)
    {
        foreach (var i in count.Times())
        {
            yield return action();
        }
    }

    public static IEnumerable<TResult> LazyTimes<TResult>(this int count, Func<int, TResult> action)
    {
        foreach (var i in count.Times())
        {
            yield return action(i);
        }
    }
}

Scenario

public class Scenario : IDisposable
{
    private readonly string message;
    private readonly Stopwatch stopwatch = new Stopwatch();
    private static int nextUid = 0;
    private int uid = nextUid+=1;

    public Scenario(string message)
    {
        this.message = message;
        stopwatch = new Stopwatch();
        Console.WriteLine(">> {{{0}}} - {1}", uid, message);
        stopwatch.Start();
    }

    public void Dispose()
    {
        stopwatch.Stop();
        var elapsed = stopwatch.Elapsed;
        
        var elements = new List(4);

        if (elapsed.Days != 0)
            elements.Add(string.Format("{0} days", elapsed.Days));

        if (elapsed.Hours != 0)
            elements.Add(string.Format("{0} hours", elapsed.Hours));

        if (elapsed.Minutes != 0)
            elements.Add(string.Format("{0} minutes", elapsed.Minutes));

        if (elapsed.Seconds != 0 && elapsed.Milliseconds != 0)
            elements.Add(string.Format("{0}.{1}s", elapsed.Seconds, elapsed.Milliseconds));

        else if (elapsed.Seconds != 0)
            elements.Add(string.Format("{0}s", elapsed.Seconds));

        else if (elapsed.Milliseconds != 0)
            elements.Add(string.Format("{0}ms", elapsed.Milliseconds));

        var formatted = new StringBuilder();
        if (elements.Count > 0)
        {
            if (elements.Count > 1)
            {
                formatted.Append(string.Join(", ", elements.Take(elements.Count - 1).ToArray()));
                formatted.Append(" and ");
            }

            formatted.Append(elements.Last());
        }
            

        Console.WriteLine(string.Format("<< {{{0}}} {1} for {2}", uid, formatted, message));
    }
}
[/sourcecode]

Lars Corneliussen

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Month: March 2009

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