What does it mean to break tests?
Disclaimer: I am new to development.

What does it mean when a developer says "When I write new code, if it has errors, it should break the tests".

I believe that this developer (that I work with) said this because the code he was maintaining had poorly written tests (from someone before him).

How can tests be written so that they break when new code is added? How can someone write a bad test?
What does it mean to break tests?
===

Disclaimer: I am new to development.

What does it mean when a developer says "When I write new code, if it has errors, it should break the tests".

I believe that this developer (that I work with) said this because the code he was maintaining had poorly written tests (from someone before him).

How can tests be written so that they break when new code is added? How can someone write a bad test?