Tests should work in the absence of a kernel (#921)

.github/workflows/continuous-integration.yml

@@ -195,6 +195,30 @@ jobs:
         - name: Upload coverage
           uses: codecov/codecov-action@v1
 
+  test-pip-no-kernel:
+    needs: skip_duplicate
+    if: ${{ needs.skip_duplicate.outputs.should_skip == 'false' }}
+    strategy:
+      matrix:
+        python-version: [ 3.7 ]
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install -r requirements.txt
+          pip install -r requirements-dev.txt
+      - name: Test with pytest
+        run: pytest --cov=./ --cov-report=xml
+      - name: Upload coverage
+        uses: codecov/codecov-action@v1
+
   build:
     name: Build
     runs-on: ubuntu-latest

codecov.yml

@@ -1,5 +1,5 @@
 comment:
-  after_n_builds: 8
+  after_n_builds: 9
 
 coverage:
   status:

docs/CHANGELOG.md

@@ -1,11 +1,18 @@
 Jupytext ChangeLog
 ==================
 
+1.13.8 (2022-02-??)
+-------------------
+
+**Fixed**
+- We made sure that our tests also work in absence of a Python kernel ([#906](https://github.com/mwouts/jupytext/issues/906))
+
+
 1.13.7 (2022-02-09)
 -------------------
 
 **Fixed**
-- The Jupytext CLI only suggest --update when the target is an .ipynb file ([#905](https://github.com/mwouts/jupytext/issues/905)) - thanks to [st--](https://github.com/st--) for this contribution
+- The Jupytext CLI only suggest `--update` when the target is an .ipynb file ([#905](https://github.com/mwouts/jupytext/issues/905)) - thanks to [st--](https://github.com/st--) for this contribution
 - We made sure that commands like `cat notebook.md | jupytext --execute` work ([#908](https://github.com/mwouts/jupytext/issues/908))
 
 **Added**

jupytext/version.py

@@ -1,3 +1,3 @@
 """Jupytext's version number"""
 
-__version__ = "1.13.7"
+__version__ = "1.13.8-dev"

tests/test_contentsmanager.py

@@ -23,6 +23,7 @@
     requires_pandoc,
     requires_quarto,
     requires_sphinx_gallery,
+    requires_user_kernel_python3,
 )
 
 
@@ -1215,6 +1216,7 @@ def test_global_pairing_allows_to_save_other_file_types(nb_file, tmpdir):
     compare_notebooks(nb2, nb)
 
 
+@requires_user_kernel_python3
 @pytest.mark.parametrize("nb_file", list_notebooks("R"))
 def test_python_kernel_preserves_R_files(nb_file, tmpdir):
     """Opening a R file with a Jupyter server that has no R kernel should not modify the file"""

tests/test_execute.py

@@ -263,6 +263,7 @@ def sample_md_notebook():
 """
 
 
+@requires_user_kernel_python3
 def test_execute_text_file_does_update_the_metadata(sample_md_notebook, tmp_path):
     md_file = tmp_path / "nb.md"
     md_file.write_text(sample_md_notebook)
@@ -274,6 +275,7 @@ def test_execute_text_file_does_update_the_metadata(sample_md_notebook, tmp_path
     assert "kernelspec" in new_md_text
 
 
+@requires_user_kernel_python3
 def test_cat_execute_does_not_update_the_metadata(sample_md_notebook, tmp_path):
     md_file = tmp_path / "nb.md"
     md_file.write_text(sample_md_notebook)

tests/test_using_cli.py

@@ -7,11 +7,12 @@
 import jupytext
 from jupytext.cli import jupytext as jupytext_cli
 
-from .utils import requires_black, requires_myst
+from .utils import requires_black, requires_myst, requires_user_kernel_python3
 
 doc_path = os.path.join(os.path.dirname(os.path.realpath(__file__)), "..", "docs")
 
 
+@requires_user_kernel_python3
 @requires_black
 @requires_myst
 @pytest.mark.skipif(