add notebook_vars utility with example notebook and unit test depicting how it can be ised to construct a pytest fixture with the notebook state after execution

open_atmos_jupyter_utils/__init__.py

@@ -4,3 +4,4 @@
 from open_atmos_jupyter_utils.pip_install_on_colab import pip_install_on_colab
 from open_atmos_jupyter_utils.temporary_file import TemporaryFile
 from open_atmos_jupyter_utils.show_plot import show_plot, save_and_make_link
+from open_atmos_jupyter_utils.notebook_vars import notebook_vars

open_atmos_jupyter_utils/notebook_vars.py

@@ -0,0 +1,31 @@
+""" helper routines for use in smoke tests """
+
+from pathlib import Path
+
+import nbformat
+
+
+def notebook_vars(file: Path, plot: bool):
+    """Executes the code from all cells of the Jupyter notebook `file` and
+    returns a dictionary with the notebook variables. If the `plot` argument
+    is set to `True`, any code line within the notebook starting with `show_plot(`
+    (see [open_atmos_jupyter_utils docs](https://pypi.org/p/open_atmos_jupyter_utils))
+    is replaced with `pyplot.show() #`, otherwise it is replaced with `pyplot.gca().clear() #`
+    to match the smoke-test conventions."""
+    notebook = nbformat.read(file, nbformat.NO_CONVERT)
+    context = {}
+    for cell in notebook.cells:
+        if cell.cell_type != "markdown":
+            lines = cell.source.splitlines()
+            for i, line in enumerate(lines):
+                if line.strip().startswith("!"):
+                    lines[i] = line.replace("!", "pass #")
+                if line.strip().startswith("show_plot("):
+                    lines[i] = line.replace(
+                        "show_plot(",
+                        "from matplotlib import pyplot; "
+                        + ("pyplot.show() #" if plot else "pyplot.gca().clear() #"),
+                    )
+
+            exec("\n".join(lines), context)  # pylint: disable=exec-used
+    return context

pyproject.toml

@@ -18,6 +18,7 @@ dependencies = [
     "IPython",
     "matplotlib",
     "imageio",
+    "nbformat"
 ]
 [project.urls]
 "Homepage" = "https://github.com/open-atmos/jupyter-utils"