Only set CIBW testing env vars if workflow input is given

.github/workflows/publish.yml

@@ -143,6 +143,18 @@ jobs:
         uses: docker/setup-qemu-action@v2
         with:
           platforms: all
+      - name: Configure cibuildwheel
+        shell: bash
+        run: |
+          if [ -n "${{ inputs.test_extras }}" ];
+          then
+            echo "CIBW_TEST_EXTRAS=${{ inputs.test_extras }}" >> $GITHUB_ENV
+          fi
+          if [ -n "${{ inputs.test_command }}" ];
+          then
+            echo "CIBW_TEST_COMMAND=${{ inputs.test_command }}" >> $GITHUB_ENV
+          fi
+          cat $GITHUB_ENV
       - uses: actions/setup-python@v4
         if: ${{ inputs.env != '' }}
         with:
@@ -164,8 +176,6 @@ jobs:
         env:
           CIBW_BUILD: ${{ matrix.CIBW_BUILD }}
           CIBW_ARCHS: ${{ matrix.CIBW_ARCHS }}
-          CIBW_TEST_EXTRAS: ${{ inputs.test_extras }}
-          CIBW_TEST_COMMAND: ${{ inputs.test_command }}
       - uses: actions/upload-artifact@v3
         with:
           path: dist/*

README.md

@@ -374,11 +374,13 @@ source distribution. By default, this is `ubuntu-latest`.
 #### test_extras
 Any `extras_requires` modifier that should be used to install the package for testing.
 Default is none.
+If not set, cibuildwheel will use any `test-extras` configured in `pyproject.toml`.
 
 #### test_command
 The command to run to test the package.
 Will be run in a temporary directory.
 Default is no testing.
+If not set, cibuildwheel will use any `test-command` configured in `pyproject.toml`.
 
 #### env
 A map of environment variables to be available when building and testing.