NAnt, NUnit and mono 1.1.17

The new release of mono contains various bug fixes, many of them concerning the AppDomain class, creation of application domains and communication between them. Unfortunately, those changes broke the <nunit2> task in NAnt scripts run on Linux (strangely, everything works fine on Windows). When executed, task reports an incompatible version of NUnit assembly used to compile the tests. However, when nant is run with -verbose switch, the real exception can be examined - mono is unable to load the NAnt.NUnit2Tasks.dll into the new AppDomain.

A temporary workaround is to execute the tests with the <exec> task. Start with defining a template target:

<target name="test-assembly">
  <if test="${platform::is-unix()}">
  <!-- nunit2 task is borked on linux with mono 1.1.17 -->
    <property
      name="nunit.exe"
      value="${framework::get-assembly-directory(framework::get-target-framework())}/nunit-console.exe" />
    <echo message="${test-assembly}" />
    <exec program="${nunit.exe}" workingdir="${binaries-dir}" useruntimeengine="true">
      <arg value="/nologo" />
      <arg value="${test-assembly}" />
    </exec>
  </if>
  <if test="${not platform::is-unix()}">
    <nunit2 verbose="true">
      <test assemblyname="${binaries-dir}/${test-assembly}" />
      <formatter type="Plain" />
    </nunit2>
  </if>
</target>

The target still calls <nunit2> task when run on Windows, as it is faster then executing nunit-console.exe. On Linux it finds the nunit-console.exe from the appropriate framework version and uses it to execute the test. To use the template, two properties have to be set:

<target name="TestObject.test" depends="TestObject.dll">
  <property name="binaries-dir" value="bin_test"/>
  <property name="test-assembly" value="TestObject.dll" />
  <call target="test-assembly" />
</target>

You can hardcode the binaries-dir or set it once for the entire build to avoid repeating it in every call to test-assembly.