Rash thoughts about .NET, C#, F# and Dynamics NAV.

"Every solution will only lead to new problems."

Category Tools

Friday, 25. February 2011

Machine.Fakes released – Built with "FAKE – F# Make"

Filed under: F#,FAKE - F# Make,Tools — Steffen Forkmann at 14:09 Uhr

My friend Björn Rochel (@BjoernRochel) built a really cool generic model for using fakes and automocking on top of Machine.Specifications (or MSpec) called Machine.Fakes (or mfakes).

Today he released version (get it from nuget.org) and I want to talk a bit about the build process. Björn and myself thought a tool called “Machine.Fakes” should of course be built with a tool called “FAKE – F# Make”. In order to do so I had to fix some stuff in Fake which resulted in the new Fake version

Here are some things I fixed:

  • New task DeleteDirs allows to delete multiple directories.
  • New parameter for NuGet task which allows to specify dependencies.
  • Bundled with docu.exe compiled against .Net 4.0.
  • Fixed docu calls to run with full filenames.
  • Added targetplatform, target and log switches for ILMerge task.
  • Added Git.Information.getLastTag() which gets the last git tag by calling git describe.
  • Added Git.Information.getCurrentHash() which gets the last current sha1.
Machine.Fakes build setup

The build script for Machine.Fakes performs the following steps:

  1. It retrieves the version no. via GitHubs REST API
  2. It cleans all directories from old stuff
  3. It compiles the app and test projects
  4. It uses MSpec to test the application
  5. It merges StructureMap and StructureMap.AutoMocking into the app by using ILMerge
  6. It generates the XML documentation using the .NET 4.0 version of docu.exe
  7. It zips the app and the documentation files
  8. It builds and deploys a Nuget package with just Machine.Fakes
  9. It builds and deploys bundled Nuget packages in the following flavors:
    1. Machine.Fakes.FakeItEasy
    2. Machine.Fakes.RhinoMocks
    3. Machine.Fakes.Moq

Now you can start using this awesome project by calling:

install-package Machine.Fakes.{Flavor}

Tags: , , ,

Tuesday, 2. June 2009

F# BootCamp – Questions and Answers – part I – Introduction

Filed under: .NET,F#,Informatik,Mathematik,Steffen,TechTalk,Tools — Steffen Forkmann at 10:34 Uhr

Last Friday we had a fantastic LearningByTeaching F# BootCamp in Leipzig. Each attendee got homework and had to solve one theoretical question and one programming task. For this two questions they had to present their results to the rest of us and after this I gave my solution in addition.

It was very interesting to see the different strategies and solutions. In this post series I will discuss the questions and some of the possible solutions.

Question 1 – What is “Functional Programming” in contrast to “Imperative Programming”?

This seems to be an easy question but in fact, the attendees had some problems to give a short definition of both functional and imperative Programming.

I didn’t find a formal definition of the terms so my intention was to clarify things with an informal description like the one from Wikipedia:

“In computer science, functional programming is a programming paradigm that treats computation as the evaluation of mathematical functions and avoids state and mutable data. It emphasizes the application of functions, in contrast to the imperative programming style, which emphasizes changes in state. Functional programming has its roots in the lambda calculus, a formal system developed in the 1930s to investigate function definition, function application, and recursion.”


I think the main aspect here is: avoiding state and mutable data. Maybe the words “side-effect”, recursion and “higher-order functions” could also be used, but they will be discussed in later questions.

On my slides I covered the following aspects:

  • Functional programming is a paradigm
  • FP tries to avoid shared state
  • Functions are first class citizens, enabling higher-order functions
  • Pure functions
    • no side-effects
    • Results calculated only on the basis of input values
    • No information storage
    • Deterministic
    • ==> Debugging and testing benefits
    • ==> Thread-safe without locking of data

For further reading I recommend "Conception, evolution, and application of functional programming languages" (Paul Hudak) or “Functional Programming For The Rest of Us” (Slava Akhmechet).

Question 2 – Explain the keyword “let”. In F# we are talking about “let-bindings” and not “variables”. Why?

Basically you use the let keyword to bind a name to a value or function. It won’t change any more, so a binding is immutable at default and not “variable”.

I was glad to see the presenter showing the problem with an imperative assignment like
x = x + 1, which from a mathematical view is paradoxical. There is no x which equals x plus one. I think choice of the F# assignment operator is better than equality sign. The statement x <- x + 1 shows the real intention. I want to put the old value of x plus one into the memory cell where x was before.
So we discussed some basic terms like scope and mutability here and I showed how we can explicitly tell the compiler to use mutable data using reference cells or mutable variables.

Maybe it wasn’t that good idea to discuss “Imperative F#” at such an early point (without knowing any functional concepts), but it showed the contrast to immutable let-Bindings.

Question 3 – What is a recursion? Try to explain why we often want recursions to be tail-recursive. Hint: Look at the following C# program. What is the problem and how could you solve it?
public static Int64 Factorial(Int64 x)
    if (x == 0) return 1;
    return x*Factorial(x - 1);

It was interesting to see that nearly nobody expected a real problem in such a short code snippet. Some attendees thought this program might have an integer overflow – but only the presenters (they tested the program) gave the right answer (stack overflow). In fact they gave a very good and deep explanation about recursion and the problem on the stack.

As the question hinted, a possible solution was adding a accumulator variable and using tail-recursion:

public static BigInt FactorialTailRecursive(BigInt x, BigInt acc)
    if (x == BigInt.Zero) return acc;
    return FactorialTailRecursive(x - BigInt.One, x*acc);

Unfortunately this "trick" doesn’t work in C# (the compiler doesn’t use tail calls), but it leads to the correct idea – converting it to a while-loop. Of course I would prefer the tail-recursive F# solution:

/// Tail recursive version
let factorial x = 
  let rec tailRecursiveFactorial x acc =
    match x with
      | y when y = 0I -> acc
      | _ -> tailRecursiveFactorial (x-1I) (acc*x)           

  tailRecursiveFactorial x 1I

We didn’t cover continuation passing here. I think this could be something for an advanced session.

Next time I will discuss the rest of the introduction and show some of the first programming tasks.

Tags: , , ,

Wednesday, 15. April 2009

Integrating a “FAKE – F# Make” build script into TeamCity

Filed under: F#,FAKE - F# Make,Tools,Visual Studio — Steffen Forkmann at 11:00 Uhr

This artile has been moved to http://fsharp.github.io/FAKE/teamcity.html

Tags: , , , , , , ,

Saturday, 4. April 2009

Modifying AssemblyInfo and Version via FAKE – F# Make

Filed under: C#,FAKE - F# Make,Tools — Steffen Forkmann at 14:54 Uhr

This article has been moved to http://fsharp.github.io/FAKE/assemblyinfo.html

Tags: , , , , ,

Thursday, 2. April 2009

Adding FxCop to a “FAKE” build script

Filed under: C#,English posts,F#,FAKE - F# Make,NaturalSpec,Tools — Steffen Forkmann at 18:19 Uhr

This post has been moved to http://fsharp.github.io/FAKE/fxcop.html

Tags: , , , , , ,

Wednesday, 1. April 2009

Getting started with “FAKE – F# Make” – Get rid of the noise in your build scripts.

Filed under: C#,English posts,F#,FAKE - F# Make,Informatik,NaturalSpec,Tools — Steffen Forkmann at 21:02 Uhr

This article has been moved to http://fsharp.github.io/FAKE/gettingstarted.html

Tags: , , , , , , ,

Monday, 23. February 2009

Introducing NaturalSpec – A Domain-specific language (DSL) for testing – Part I

Filed under: C#,F#,NaturalSpec,Tools — Steffen Forkmann at 11:31 Uhr

Test-Driven development (TDD) is a well known software development technique and follows the mantra “Red-Green-Refactor”. Behavior-Driven Development (BDD) is a response to TDD and introduces the idea of using natural language to express the Unit Test scenarios.

There are a lot of popular testing frameworks around which can be used for BDD including xUnit.net ,NUnit, StoryQ, MSpec, NSpec and NBehave. Most of them can be used with fluent interfaces and therefore provides a good readability of the sources. Some of them even provide the possibility to generate a spec in natural language out of passed Unit tests.

What is a spec?

“A specification is an explicit set of requirements to be satisfied by a material, product, or service.”

American Society for Testing and Materials (ASTM) definition

A spec is an important document for the communication process – it enables domain experts to communicate with developers. But how can you verify the compliance with the spec? The answer is: you have to write unit tests. Even with the mentioned frameworks there is a lot of work to do in order to translate a spec scenario into a Unit Test.

Question 7 in the famous Joel Test is “Do you have a spec?”.

The idea of NaturalSpec is to give domain experts the possibility to express their scenarios directly in compilable Unit Test scenarios by using a Domain-specific language (DSL) for Unit Tests. NaturalSpec is completely written in F# – but you don’t have to learn F# to use it. You don’t even have to learn programming at all.

Example 1 – Specifying a list

Let’s consider a small example. If we want to test a new List implementation a spec could look like this:

let When_removing_an_3_from_a_small_list_it_should_not_contain_3() =
  Given [1;2;3;4;5]              // “Arrange” test context
    |> When removing 3           // “Act|> It shouldn't contain 3    // “Assert|> It should contain 4       // another assertion
    |> Verify                    // Verify scenario

I used BDD style here and expressed my scenario in a quite natural language. As the comments are indicating the scenario is following the Arrange Act Assert (“AAA”) pattern.

With the Keyword “Given” I can create a test context (the objects I want to test). In this sample I created a list with 5 elements. With the keyword “When” I call a function which does something with my test context. In this case I want to remove the value 3. In the Assert section (keywords “It should” or “It shouldn’t”) I can give some observations, which should hold for my manipulated test context.

When I run this scenario via a NUnit runner (i am using TestDriven.Net) I get the following output:

Scenario: When removing an 3 from a small list it should not contain 3

– Given [1; 2; 3; 4; 5]
– When removing 3
=> It should not contain 3
=> It should contain 4
==> OK

Example 2 – Specifying a factorial function

If you implement factorial function the spec could look like this:

let When_calculating_fac_5_it_should_equal_120() =
  Given 5
    |> When calculating factorial
    |> It should equal 120
    |> Verify    

let When_calculating_fac_1_it_should_equal_1() =
  Given 1
    |> When calculating factorial
    |> It should equal 1
    |> Verify          

let When_calculating_fac_0_it_should_equal_0() =
  Given 0
    |> When calculating factorial
    |> It should equal 1
    |> Verify

And the output of NaturalSpec would look like this:

Scenario: When calculating fac 0 it should equal 0

– Given 0
– When calculating factorial
=> It should equal 1
==> OK

Scenario: When calculating fac 1 it should equal 1

– Given 1
– When calculating factorial
=> It should equal 1
==> OK

Scenario: When calculating fac 5 it should equal 120

– Given 5
– When calculating factorial
=> It should equal 120
==> OK

Getting started

Of course you can use NaturalSpec to specify C# objects. I see my post "Using NaturalSpec to create a spec for C# projects" for a small sample.

You can download NaturalSpec at GoogleCode and follow the “Getting started” tutorial in order to write your first automatically testable spec.

I am very interested in your feedback. Do you like the syntax? What should I change? Do you consider using a spec tool like NaturalSpec?

Tags: , , , , , , , , , , ,

Sunday, 11. January 2009

ReSharper 4.5 and F#

Filed under: F#,Tools — Steffen Forkmann at 19:16 Uhr

Since I am working with hybrid solutions (with F# and C# projects in it) I had to deactivate ReSharper. ReSharper had a problem with analyzing my F# sources (see JIRA bug entry #79203). The result was that every single F# defined type and function was marked as an error. I nearly got crazy. On one hand I got used to all the nice ReSharper refactorings (and the NUnit runner) and on the other I got all these false positive errors.

But from now on this hard times are over. Today I tested build 1153 (see nightly builds for version 4.5) – and everything works fine.

ReSharper is running again

Thank you guys at JetBrains. 🙂

Tags: , ,

How I do Continuous Integration with my C# / F# projects – part IV: Adding a documentation

Filed under: C#,English posts,F#,Tools,Visual Studio — Steffen Forkmann at 12:46 Uhr

In the last 3 posts I show how to set up a Continuous Integration environment for F# or C# projects with Subversion (part I), TeamCity (part II) and NUnit (part III).

This time I want to show how we can set up an automated documentation build.

Installing and using GhostDoc

“GhostDoc is a free add-in for Visual Studio that automatically generates XML documentation comments for C#. Either by using existing documentation inherited from base classes or implemented interfaces, or by deducing comments from name and type of e.g. methods, properties or parameters.”

[product website]

GhostDoc is one of my favorite Visual Studio plugins. It allows me to generate comments for nearly all my C# functions. Of course these generated comments aren’t sufficient in every case – but they are a very good start.

Unfortunately GhostDoc doesn’t work for F# 🙁 – the actual version works for C# and the support for VB.Net is called “experimental”.

Download and install http://www.roland-weigelt.de/ghostdoc/.

Now you should be able to generate XML-based comments directly in your C# code:

Using GhostDoc

Generated XML-comment

The next step is to activate the xml-documentation in your Visual Studio build settings:


Commiting these changes and adjusting the build artifacts will produce the input for the documentation build:

Adjust the build artifacts

Build artifacts

Using Sandcastle to generate a documentation

“Sandcastle produces accurate, MSDN style, comprehensive documentation by reflecting over the source assemblies and optionally integrating XML Documentation Comments. Sandcastle has the following key features:

  • Works with or without authored comments
  • Supports Generics and .NET Framework 2.0
  • Sandcastle has 2 main components (MrefBuilder and Build Assembler)
  • MrefBuilder generates reflection xml file for Build Assembler
  • Build Assembler includes syntax generation, transformation..etc
  • Sandcastle is used internally to build .Net Framework documentation


Download and install “Sandcastle – Documentation Compiler for Managed Class Libraries” from Mircosoft’s downloadpage or http://www.codeplex.com/Sandcastle.

For .chm generation you also have to install the “HTML Help Workshop“. If you want fancy HTMLHelp 2.x style (like MSDN has) you need “Innovasys HelpStudio Lite” which is part of the Visual Studio 2008 SDK.

“HelpStudio Lite is offered with the Visual Studio SDK as an installed component that integrates with Visual Studio. HelpStudio Lite provides a set of authoring tools you use to author and build Help content, create and manage Help projects, and compile Help files that can be integrated with the Visual Studio Help collection.”


Last but not least I recommend to install the Sandcastle Help File Builder (SHFB) – this tool gives you a GUI and helps to automate the Sandcastle process.

“Sandcastle, created by Microsoft, is a tool used for creating MSDN-style documentation from .NET assemblies and their associated XML comments files. The current version is the May 2008 release. It is command line based and has no GUI front-end, project management features, or an automated build process like those that you can find in NDoc. The Sandcastle Help File Builder was created to fill in the gaps, provide the missing NDoc-like features that are used most often, and provide graphical and command line based tools to build a help file in an automated fashion.”

[product homepage]

After the installation process start SHFB to generate a documentation project:

Sandcastle Help File Builder

Add the TestCITestLib.dll to your project and add nunit.framework.dll as a dependency. Now try to compile your help project – if everything is fine the output should look something like this:

Generated Help

Setting up the documentation build

One of the main principles of Continuous Integration is “Keep the Build Fast” – so I am working with staged builds here. The documentation build should only be started if the first build was successful and all UnitTests are positive. For most projects it is enough to generate the documentation daily or even weekly.

First of all we have to create a simple MSBuild file which executes the SHFB project:

<Project ToolsVersion="3.5" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <!-- 3rd Party Program Settings -->
    <SandCastleHFBPath>c:\Program Files (x86)\EWSoftware\Sandcastle Help File Builder\</SandCastleHFBPath>

  <Target Name="BuildDocumentation">
    <!-- Build source code docs -->
    <Exec Command="%22$(SandCastleHFBCmd)%22 %22$(SandCastleHFBProject)%22" />

Add this build file and the SHFB project to your Visual Studio solution folder and commit these changes.

Put the build settings into the solution folder

Now we can create a new TeamCity build configuration:

Create a new build configuration

Take the same Version Control Settings like in the first build but use MSBuild as the build runner:

Take the MSBuild runner

We want the documentation to be generated after a successful main build so we add a “dependency build trigger”:


Now we need the artifacts from the main build as the input for our documentation build:

Set up artifacts dependencies

Be sure you copy the artifacts to the right directory as given in your .shfb-project. Now run the DocumentationBuild – if everything is fine the DocumentationBuild should give you the Documentation.chm as a new artifact:


Tags: , , , , , , , , , ,

Thursday, 8. January 2009

How I do Continuous Integration with my C# / F# projects – part III: Running automated UnitTests

Filed under: C#,English posts,F#,Tools,Visual Studio — Steffen Forkmann at 19:13 Uhr

In the last two posts I showed how to set up a Subversion (part I: Setting up Source Control) and a TeamCity server (part II: Setting up a Continuous Integration Server).

This time I will show how we can integrate NUnit to run automated test at each build. TeamCity supports all major Testing Frameworks (including MS Test) but I will concentrate on NUnit here.

"NUnit is a unit-testing framework for all .Net languages. Initially ported from JUnit, the current production release, version 2.4, is the fifth major release of this xUnit based unit testing tool for Microsoft .NET. It is written entirely in C# and has been completely redesigned to take advantage of many .NET language features, for example custom attributes and other reflection related capabilities. NUnit brings xUnit to all .NET languages."

[product homepage]

Creating a TestProject

First of all download and install NUnit 2.4.8 (or higher) from http://www.nunit.org/.

Now we add a small function to our F# source code:

let rec factorial = function  
  | 0 -> 1
  | n when n > 0 -> n * factorial (n-1)
  | _ -> invalid_arg "Argument not valid"

This is the function we want to test. We add a new C# class library to our solution (e.g. “TestCITestLib” 😉 ) and add a reference to nunit.framework. Inside this new TestLibrary we add a TestClass with the following code:

namespace TestCITestLib
    using NUnit.Framework;

    public class FactorialTest
        public void TestFactorial()
            Assert.AreEqual(1, Program.factorial(0));
            Assert.AreEqual(1, Program.factorial(1));
            Assert.AreEqual(120, Program.factorial(5));

        public void TestFactorialException()

To ensure the build runner is able to compile our solution we put the nunit.framework.dll near to our TestProject and commit our changes.

Adding Nunit.framework.dll

Configure TeamCity for UnitTesting

The next step is to tell TeamCity that the build runner should run our UnitTests:

Configure build runner for NUnit

If we now run the build we should get the following error:

UnitTest error during automated build

Our second test function failed, because we didn’t expect the System.ArgumentException. We can fix this issue by adding the corresponding attribute to the Testfunction:

public void TestFactorialException()

Tests passed

Configure the build output

At this point we have a minimalistic Continuous Integration infrastructure. Every time someone performs a Commit on our repository a automated build will be started and the sources will be tested against the given UnitTests. Now we should concentrate on getting our build output – the artifacts. The term artifact is usually used to refer to files or directories produced during a build. Examples of such artifacts are:

  • Binaries (*.exe, *.dll)
  • Software packages and installers (*.zip, *.msi)
  • Documentation files (e.g. help files)
  • Reports (test reports, coverage reports, …)

At this time we are only interested in the binaries (this means CITestLib.dll). We can add the following artifact definition to our TeamCity project:

Configure artifacts in TeamCity

If we now rebuild our solution the build runner collects the configured artifacts and stores them with all build information:

Collected artifacts

Next time I will show how we can add more artifacts – e.g. an automated documentation.

Tags: , , , , , , , , ,