Better tests directory structure (#2231)

tests/hierarchy/images_hierarchy.py

@@ -0,0 +1,38 @@
+# Copyright (c) Jupyter Development Team.
+# Distributed under the terms of the Modified BSD License.
+from pathlib import Path
+
+THIS_DIR = Path(__file__).parent.resolve()
+IMAGE_SPECIFIC_TESTS_DIR = THIS_DIR.parent / "image_specific_tests"
+
+assert IMAGE_SPECIFIC_TESTS_DIR.exists(), f"{IMAGE_SPECIFIC_TESTS_DIR} does not exist."
+
+# Please, take a look at the hierarchy of the images here:
+# https://jupyter-docker-stacks.readthedocs.io/en/latest/using/selecting.html#image-relationships
+ALL_IMAGES = {
+    "docker-stacks-foundation": None,
+    "base-notebook": "docker-stacks-foundation",
+    "minimal-notebook": "base-notebook",
+    "scipy-notebook": "minimal-notebook",
+    "r-notebook": "minimal-notebook",
+    "julia-notebook": "minimal-notebook",
+    "tensorflow-notebook": "scipy-notebook",
+    "pytorch-notebook": "scipy-notebook",
+    "datascience-notebook": "scipy-notebook",
+    "pyspark-notebook": "scipy-notebook",
+    "all-spark-notebook": "pyspark-notebook",
+}
+
+
+def get_test_dirs(
+    short_image_name: str | None,
+) -> list[Path]:
+    if short_image_name is None:
+        return []
+
+    test_dirs = get_test_dirs(ALL_IMAGES[short_image_name])
+    if (
+        current_image_tests_dir := IMAGE_SPECIFIC_TESTS_DIR / short_image_name
+    ).exists():
+        test_dirs.append(current_image_tests_dir)
+    return test_dirs