New Post: Creating environment variables in a Project with merge modules fails.

class Script
{
    staticpublicvoid Main(string[] args)
    {
        var featureA = new Feature("Feature A", "Feature A description");
        var featureB = new Feature("Feature B", "Feature B description");
        var complete = new Feature("Complete");

        complete.Add(featureA)
                .Add(featureB);

        var project =
                new Project("MyMergeModuleSetup",
                    new Dir(@"%ProgramFiles%\My Company",
                        new File(featureA, @"Files\MainFile.txt"),
                        new Merge(featureB, @"Files\MyMergeModule.msm"),
                        new Merge(featureB, @"Files\MyMergeModule1.msm")),
                    new EnvironmentVariable("foo", "bar"));

        project.DefaultFeature = complete;
        project.UI = WUI.WixUI_FeatureTree;
        project.InstallerVersion = 200; //you may want to change it to match MSM module installer version

        project.PreserveTempFiles = true;

        project.BuildMsi();
    }
}