ensure extension modules are present in built wheel (#256)

* add test command to import c extension modules

* add comment about test_command in cibuildwheel

* fix import syntax

.github/workflows/build.yml

@@ -23,5 +23,6 @@ jobs:
         # Until we have arm64 runners, we can't automatically test arm64 wheels
         - cp3*-macosx_arm64
       sdist: true
+      test_command: python -c "from stcal.ramp_fitting.ols_cas22 import _ramp, _jump, _fit"
     secrets:
       pypi_token: ${{ secrets.PYPI_PASSWORD_STSCI_MAINTAINER }}

setup.py

@@ -6,6 +6,8 @@
 Options.docstrings = True
 Options.annotate = False
 
+# importing these extension modules is tested in `.github/workflows/build.yml`; 
+# when adding new modules here, make sure to add them to the `test_command` entry there
 extensions = [
     Extension(
         "stcal.ramp_fitting.ols_cas22._ramp",