From ba1ef06bf31a65f379fe6612d6eb154f8a61ec90 Mon Sep 17 00:00:00 2001
From: eeshsaxena <eeshsaxena@gmail.com>
Date: Mon, 6 Jul 2026 09:49:53 +0530
Subject: [PATCH] test: add unit tests for relative_import

---
 tests/test_core/test_utils/test_importers.py | 40 ++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 tests/test_core/test_utils/test_importers.py

diff --git a/tests/test_core/test_utils/test_importers.py b/tests/test_core/test_utils/test_importers.py
new file mode 100644
index 00000000000..7c46a7c972b
--- /dev/null
+++ b/tests/test_core/test_utils/test_importers.py
@@ -0,0 +1,40 @@
+import collections.abc
+
+import pytest
+
+from _plotly_utils.importers import relative_import
+
+
+def _make():
+    # Use the stdlib ``collections`` package as a stable lazy-import target.
+    return relative_import(
+        "collections",
+        rel_modules=[".abc"],
+        rel_classes=[".abc.Mapping"],
+    )
+
+
+def test_all_lists_module_and_class_leaf_names():
+    all_, _getattr, _dir = _make()
+    assert sorted(all_) == ["Mapping", "abc"]
+
+
+def test_getattr_lazily_imports_submodule():
+    _all, getattr_, _dir = _make()
+    assert getattr_("abc") is collections.abc
+
+
+def test_getattr_lazily_imports_class():
+    _all, getattr_, _dir = _make()
+    assert getattr_("Mapping") is collections.abc.Mapping
+
+
+def test_getattr_unknown_name_raises_attribute_error():
+    _all, getattr_, _dir = _make()
+    with pytest.raises(AttributeError):
+        getattr_("does_not_exist")
+
+
+def test_dir_returns_all():
+    all_, _getattr, dir_ = _make()
+    assert sorted(dir_()) == sorted(all_)