It's an extremely common problem in legacy code bases: a new way of doing things was introduced before the team decided on a way to get the old thing out.
I've mentioned this several times without explaining: the rule that every class should have a test, or that every class method should have a test, does not make sense at all. Still, it's a rule that many teams follow. Why? Maybe they used to have a #NoTest culture and they never want to go back to it, so they establish a rule that is easy to enforce. When reviewing you only have to check: does the class have a test? Okay, great. It's a bad test? No problem, it is a test. I already explained why I think you need to make an effort to not just write any test, but to write good tests (see also: Testing Anything; Better Than Testing Nothing?). In this article I'd like to look closer at the numbers: one class - one test.
I'm a big fan of the BDD Books by Gáspár Nagy and Seb Rose, and I've read a lot about writing and improving scenarios, like Specification by Example by Gojko Adzic and Writing Great Specifications by Kamil Nicieja. I can recommend reading anything from Liz Keogh as well. Trying to apply their suggestions in my development work, I realized: specifications benefit from good writing. Writing benefits from good thinking. And so does design. Better writing, thinking, designing: this will make us do a better job at programming. Any effort put into these activities has a positive impact on the other areas, even on the code itself.