I'm not 100% sure what this refers to, but you can do stuff like this in mocha, which might solve the problem:

    Puppet::Type::Sysctl::ProviderAugeas.expects(:sysctl_get).with('net.ipv4.ip_forward').returns('1').twice()
    Puppet::Type::Sysctl::ProviderAugeas.expects(:sysctl_get).with('net.ipv4.ip_forward').returns('0").then.returns("1")