Turn the tests notebooks into fixtures

src/jupytext/cli.py

@@ -50,6 +50,15 @@ def system(*args, **kwargs):
     return out.decode("utf-8")
 
 
+def tool_version(tool):
+    try:
+        args = tool.split(" ")
+        args.append("--version")
+        return system(*args)
+    except (OSError, SystemExit):  # pragma: no cover
+        return None
+
+
 def str2bool(value):
     """Parse Yes/No/Default string
     https://stackoverflow.com/questions/15008758/parsing-boolean-values-with-argparse"""

src/jupytext/compare.py

@@ -2,13 +2,16 @@
 
 import difflib
 import json
+import os
 import re
 
+from jupytext.paired_paths import full_path
+
 from .cell_metadata import _IGNORE_CELL_METADATA
 from .combine import combine_inputs_with_outputs
-from .formats import long_form_one_format
+from .formats import check_auto_ext, long_form_one_format
 from .header import _DEFAULT_NOTEBOOK_METADATA
-from .jupytext import reads, writes
+from .jupytext import read, reads, write, writes
 from .metadata_filter import filter_metadata
 
 _BLANK_LINE = re.compile(r"^\s*$")
@@ -388,3 +391,75 @@ def test_round_trip_conversion(
         allow_expected_differences,
         raise_on_first_difference=stop_on_first_error,
     )
+
+
+# The functions below are used in the Jupytext text collection
+def create_mirror_file_if_missing(mirror_file, notebook, fmt):
+    if not os.path.isfile(mirror_file):
+        write(notebook, mirror_file, fmt=fmt)
+
+
+def assert_conversion_same_as_mirror(nb_file, fmt, mirror_name, compare_notebook=False):
+    """This function is used in the tests"""
+    dirname, basename = os.path.split(nb_file)
+    file_name, org_ext = os.path.splitext(basename)
+    fmt = long_form_one_format(fmt)
+    notebook = read(nb_file, fmt=fmt)
+    fmt = check_auto_ext(fmt, notebook.metadata, "")
+    ext = fmt["extension"]
+    mirror_file = os.path.join(
+        dirname, "..", "..", "outputs", mirror_name, full_path(file_name, fmt)
+    )
+
+    # it's better not to have Jupytext metadata in test notebooks:
+    if fmt == "ipynb" and "jupytext" in notebook.metadata:  # pragma: no cover
+        notebook.metadata.pop("jupytext")
+        write(nb_file, fmt=fmt)
+
+    create_mirror_file_if_missing(mirror_file, notebook, fmt)
+
+    # Compare the text representation of the two notebooks
+    if compare_notebook:
+        # Read and convert the mirror file to the latest nbformat version if necessary
+        nb_mirror = read(mirror_file, as_version=notebook.nbformat)
+        nb_mirror.nbformat_minor = notebook.nbformat_minor
+        compare_notebooks(nb_mirror, notebook)
+        return
+    elif ext == ".ipynb":
+        notebook = read(mirror_file)
+        fmt.update({"extension": org_ext})
+        actual = writes(notebook, fmt)
+        with open(nb_file, encoding="utf-8") as fp:
+            expected = fp.read()
+    else:
+        actual = writes(notebook, fmt)
+        with open(mirror_file, encoding="utf-8") as fp:
+            expected = fp.read()
+
+    if not actual.endswith("\n"):
+        actual = actual + "\n"
+    compare(actual, expected)
+
+    # Compare the two notebooks
+    if ext != ".ipynb":
+        notebook = read(nb_file)
+        nb_mirror = read(mirror_file, fmt=fmt)
+
+        if fmt.get("format_name") == "sphinx":
+            nb_mirror.cells = nb_mirror.cells[1:]
+            for cell in notebook.cells:
+                cell.metadata = {}
+            for cell in nb_mirror.cells:
+                cell.metadata = {}
+
+        compare_notebooks(nb_mirror, notebook, fmt)
+
+        nb_mirror = combine_inputs_with_outputs(nb_mirror, notebook)
+        compare_notebooks(nb_mirror, notebook, fmt, compare_outputs=True)
+
+
+def notebook_model(nb):
+    """Return a notebook model, with content a
+    dictionary rather than a notebook object.
+    To be used in tests only."""
+    return dict(type="notebook", content=json.loads(json.dumps(nb)))

src/jupytext/formats.py

@@ -40,7 +40,7 @@
     myst_extensions,
     myst_version,
 )
-from .pandoc import pandoc_version
+from .pandoc import is_pandoc_available, pandoc_version
 from .stringparser import StringParser
 from .version import __version__
 
@@ -825,3 +825,13 @@ def check_auto_ext(fmt, metadata, option):
             option, short_form_one_format(fmt)
         )
     )
+
+
+def formats_with_support_for_cell_metadata():
+    for fmt in JUPYTEXT_FORMATS:
+        if fmt.format_name == "myst" and not is_myst_available():
+            continue
+        if fmt.format_name == "pandoc" and not is_pandoc_available():
+            continue
+        if fmt.format_name not in ["sphinx", "nomarker", "spin", "quarto"]:
+            yield f"{fmt.extension[1:]}:{fmt.format_name}"