Most french-speaking professional programmers I’ve worked with will translate “Unit Test” by “Test Unitaire”. This is indeed the term used by the french translation of the Wikipedia article on unit testing.

Forgive my obsessive-compulsive disorder, but I believe the proper french translation of “unit test” should be “test unité”, and not “test unitaire”.

The english “unit” and the french “unitaire” mean two completely different things. “Unit” refers to a small, indivisible part of a system. “Unitaire” is a word that I have never seen used outside of linear algebra. For example a “matrice unitaire” (“unitary matrix“) refers to a complex matrix $U$ whose inverse is its conjugate transpose: $U \times U^* = I$.

I don’t know what a “test unitaire” is, nor do I know that a unitary test is. I do know, however, that a unit test is a test that tests a unit. Therefore, I also know that a “test unité” is a test that tests an “unité”.