You can't successfully own code that you don't control.
I believe that the best outcome for both of you would be 20% of time set aside for refactoring and increasing test coverage. Sure you'd want more but features have to roll out too. Management may not realise that refactoring that much is necessary.
You may have to pad out estimates of new work, and say things like "in order to do that we'd have to understand the guts of the foo subsystem, and make sure that we don't break it while we change it, so we'll have to put tests around it while we change the code" while mentally adding a week's time refactoring and adding unit test coverage to foo to your estimate. Grease the moving parts - things that change once tend to change again, and you'll be happier the second time around.
If you can't even do that, ask them what they mean by "take ownership". Maybe they just want you to the go-to-guy for that particular monster. Say what would do if you really owned it. If you are completely overruled, you may have to be blunt and point out that this is not ownership in any non-bullshit sense.
If that fails, as the wise man said: if you can't change your company, change your company.
I believe that the best outcome for both of you would be 20% of time set aside for refactoring and increasing test coverage. Sure you'd want more but features have to roll out too. Management may not realise that refactoring that much is necessary.
You may have to pad out estimates of new work, and say things like "in order to do that we'd have to understand the guts of the foo subsystem, and make sure that we don't break it while we change it, so we'll have to put tests around it while we change the code" while mentally adding a week's time refactoring and adding unit test coverage to foo to your estimate. Grease the moving parts - things that change once tend to change again, and you'll be happier the second time around.
If you can't even do that, ask them what they mean by "take ownership". Maybe they just want you to the go-to-guy for that particular monster. Say what would do if you really owned it. If you are completely overruled, you may have to be blunt and point out that this is not ownership in any non-bullshit sense.
If that fails, as the wise man said: if you can't change your company, change your company.