I do think that as a matter of principle having test coverage for the different intrinsics we implement is simply a good idea. These tests don't necessarily need to be complicated; see e.g. "sqrt.shader_test" for a straightforward example.
For the record, at some point I duplicated some tests so that both the constant folding path and the real codegen path would be tested. See for example `arithmetic-float.shader_test` vs `arithmetic-float-uniform.shader_test`. It wouldn't probably be a bad idea to make that more systematic, but I agree that's not a requirement for this MR. Just saying.