Before coming to MS, I wrote a bunch of general purpose NAnt scripts to help people do things like automate their builds, set up CC.NET and other fun things.
Of course, you have to imagine that I couldn’t just sit here and not explore MSBuild a bit here and there.
So while putting together a bootstrap MSBuild file for our build server, I discovered a cool feature I wish NAnt had had “back in the day”: Custom Metadata.
Suppose I want to create a target called UnitTest that called NUnit-Console.exe on a number of assemblies. Also assume that for various reasons, I can’t use wildcards to figure out which assemblies to use. I have to specify which specific assemblies I want it to run against.
One more thing, I want the tests to run with the current working directory set to the bin\Debug directory for that test assembly.
In NAnt, I would have had to use <foreach> and a number of other nasty property constructs, but in MSBuild it is a simple as this. (Please note the line numbers… I have manually wrapped some lines to make them fit on the page better.)
1: <?xml version="1.0" encoding="utf-8" ?>
2: <Project DefaultTargets="BuildAll"
xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
3: <PropertyGroup>
4: <NUnitExe>"C:\Program Files\NUnit V2.1\bin\nunit-console.exe"</NUnitExe>
5: <NUnitArgs>/nologo</NUnitArgs>
6: </PropertyGroup>
7:
8: <PropertyGroup Condition="!Exists('$(Configuration)')"> 9: <Configuration>Debug</Configuration>
10: </PropertyGroup>
11:
12: <ItemGroup>
13: <TestAssembly Include="Microsoft.Practices.ComponentModel.Tests.dll">
14: <WorkingDirectory>$(MSBuildProjectDirectory)\UnitTests\ComponentModel
\bin\$(Configuration)</WorkingDirectory>
15: </TestAssembly>
16: <TestAssembly Include="Microsoft.ApplicationBlocks.CompositeUI.Tests.dll">
17: <WorkingDirectory>$(MSBuildProjectDirectory)\UnitTests
\CompositeUI\bin\$(Configuration)</WorkingDirectory>
18: </TestAssembly>
19: </ItemGroup>
20:
21: <Target Name="BuildAll" DependsOnTargets="Clean;Compile;UnitTest" />
22:
23: <Target Name="Clean">
24: <MSBuild Projects="CompositeUI-CS.sln" Properties="Configuration=$(Configuration)"
Targets="Clean" />
25: </Target>
26:
27: <Target Name="Compile">
28: <MSBuild Projects="CompositeUI-CS.sln" Properties="Configuration=$(Configuration)" />
29: </Target>
30:
31: <Target Name="UnitTest" DependsOnTargets="Compile">
32: <Exec ContinueOnError='true' Command='$(NUnitEXE) $(NUnitArgs) @(TestAssembly)'
WorkingDirectory='%(WorkingDirectory)' />
33: </Target>
34: </Project>
Pretty cool, eh?
The “trick” is in the UnitTest target. The @(TestAssembly) tells MSBuild to do that task once for each item named “TestAssembly” in the above <ItemGroup>. The %(WorkingDirectory) says to pull the WorkingDirectory metadata element from the specific TestAssembly item that is being used for that task.
That is very cool. I think I may be able to find all kinds of interesting uses for this kind of custom metadata. I certainly don’t think I could have written the same funtionality in NAnt with a script this short.
Also, there is a bunch of built-in, so called “Well Known Metadata” documented over in MSDN. Check it out.
