some new features

.venv/lib/python3.12/site-packages/matplotlib/tests/test_backend_nbagg.py

@@ -0,0 +1,42 @@
+import os
+from pathlib import Path
+from tempfile import TemporaryDirectory
+
+import pytest
+
+from matplotlib.testing import subprocess_run_for_testing
+
+nbformat = pytest.importorskip('nbformat')
+pytest.importorskip('nbconvert')
+pytest.importorskip('ipykernel')
+
+# From https://blog.thedataincubator.com/2016/06/testing-jupyter-notebooks/
+
+
+def test_ipynb():
+    nb_path = Path(__file__).parent / 'test_nbagg_01.ipynb'
+
+    with TemporaryDirectory() as tmpdir:
+        out_path = Path(tmpdir, "out.ipynb")
+        subprocess_run_for_testing(
+            ["jupyter", "nbconvert", "--to", "notebook",
+             "--execute", "--ExecutePreprocessor.timeout=500",
+             "--output", str(out_path), str(nb_path)],
+            env={**os.environ, "IPYTHONDIR": tmpdir},
+            check=True)
+        with out_path.open() as out:
+            nb = nbformat.read(out, nbformat.current_nbformat)
+
+    errors = [output for cell in nb.cells for output in cell.get("outputs", [])
+              if output.output_type == "error"]
+    assert not errors
+
+    import IPython
+    if IPython.version_info[:2] >= (8, 24):
+        expected_backend = "notebook"
+    else:
+        # This code can be removed when Python 3.12, the latest version supported by
+        # IPython < 8.24, reaches end-of-life in late 2028.
+        expected_backend = "nbAgg"
+    backend_outputs = nb.cells[2]["outputs"]
+    assert backend_outputs[0]["data"]["text/plain"] == f"'{expected_backend}'"