template-regen.md

Template Regen

Template re-generating performs the following action

• Delete the existing template files.
• Create a new template database.
• Apply the default schema and data as defined by the buildTemplate parameter in the SqlInstance constructor.
• Detach the database

Re-generating the template database is a relatively expensive operation. Ideally, it should only be performed when the default schema and data requires a change. To enable this a timestamp convention is used. When the template is re-generating, its file creation time is set to a timestamp. On the next run, that timestamp is compared to avoid re-generation on a match. The timestamp can be controlled via timestamp parameter in the SqlInstance constructor.

If timestamp parameter is not defined the following conventions are used:

• For Raw SQL the last modified time of the calling Assembly using Assembly.GetCallingAssembly. This will usually result in the last modified time of the unit test assembly, and hence avoid re-generation unless a solution build has occurred.
• For EntityFramework the last modified time of the Assembly containing the DataContext.

There is a timestamp helper class to help derive last modified time of an Assembly (if the above conventions do not suffice):

public static class Timestamp
{
    public static DateTime LastModified(Delegate @delegate)
    {
        if (@delegate.Target is not null)
        {
            var targetAssembly = @delegate.Target.GetType().Assembly;
            return LastModified(targetAssembly);
        }

        var declaringAssembly = @delegate.Method.DeclaringType!.Assembly;
        return LastModified(declaringAssembly);
    }

    public static DateTime LastModified(Assembly assembly)
        => File.GetLastWriteTime(assembly.Location);

    public static DateTime LastModified<T>()
        => File.GetLastWriteTime(typeof(T).Assembly.Location);
}

^{snippet source | anchor}