From aeda7ac09f24bbef95054b14607330cb966ab820 Mon Sep 17 00:00:00 2001
From: Dino Viehland <dinoviehland@fb.com>
Date: Mon, 27 Oct 2025 10:13:38 -0700
Subject: [PATCH] Add tests for __lazy_import__

---
 Lib/test/test_import/__init__.py              | 27 +++++++++++++++++++
 .../data/lazy_imports/dunder_lazy_import.py   |  1 +
 .../dunder_lazy_import_builtins.py            | 13 +++++++++
 .../lazy_imports/dunder_lazy_import_used.py   |  2 ++
 4 files changed, 43 insertions(+)
 create mode 100644 Lib/test/test_import/data/lazy_imports/dunder_lazy_import.py
 create mode 100644 Lib/test/test_import/data/lazy_imports/dunder_lazy_import_builtins.py
 create mode 100644 Lib/test/test_import/data/lazy_imports/dunder_lazy_import_used.py

diff --git a/Lib/test/test_import/__init__.py b/Lib/test/test_import/__init__.py
index 028fe23facf..e3b47fb37b7 100644
--- a/Lib/test/test_import/__init__.py
+++ b/Lib/test/test_import/__init__.py
@@ -2809,6 +2809,33 @@ def test_lazy_import_pkg_cross_import(self):
         self.assertEqual(type(g["x"]), int)
         self.assertEqual(type(g["b"]), types.LazyImportType)
 
+    def test_dunder_lazy_import(self):
+        try:
+            import test.test_import.data.lazy_imports.dunder_lazy_import
+        except ImportError as e:
+            self.fail('lazy import failed')
+
+        self.assertFalse("test.test_import.data.lazy_imports.basic2" in sys.modules)
+
+    def test_dunder_lazy_import_used(self):
+        try:
+            import test.test_import.data.lazy_imports.dunder_lazy_import_used
+        except ImportError as e:
+            self.fail('lazy import failed')
+
+        self.assertTrue("test.test_import.data.lazy_imports.basic2" in sys.modules)
+
+    def test_dunder_lazy_import_builtins(self):
+        """__lazy_import__ uses modules __builtins__ to get __import__"""
+        try:
+            from test.test_import.data.lazy_imports import dunder_lazy_import_builtins
+        except ImportError as e:
+            self.fail('lazy import failed')
+
+        self.assertFalse("test.test_import.data.lazy_imports.basic2" in sys.modules)
+        self.assertEqual(dunder_lazy_import_builtins.basic, 42)
+
+
 class TestSinglePhaseSnapshot(ModuleSnapshot):
     """A representation of a single-phase init module for testing.
 
diff --git a/Lib/test/test_import/data/lazy_imports/dunder_lazy_import.py b/Lib/test/test_import/data/lazy_imports/dunder_lazy_import.py
new file mode 100644
index 00000000000..1a8a19c3c90
--- /dev/null
+++ b/Lib/test/test_import/data/lazy_imports/dunder_lazy_import.py
@@ -0,0 +1 @@
+basic = __lazy_import__('test.test_import.data.lazy_imports.basic2')
diff --git a/Lib/test/test_import/data/lazy_imports/dunder_lazy_import_builtins.py b/Lib/test/test_import/data/lazy_imports/dunder_lazy_import_builtins.py
new file mode 100644
index 00000000000..594bf2b3042
--- /dev/null
+++ b/Lib/test/test_import/data/lazy_imports/dunder_lazy_import_builtins.py
@@ -0,0 +1,13 @@
+import sys
+
+def myimport(*args):
+    return sys.modules[__name__]
+
+
+new_globals = dict(globals())
+new_globals["__builtins__"] = {
+    "__import__": myimport,
+}
+basic2 = 42
+basic = __lazy_import__("test.test_import.data.lazy_imports", fromlist="basic2", globals=new_globals)
+basic
diff --git a/Lib/test/test_import/data/lazy_imports/dunder_lazy_import_used.py b/Lib/test/test_import/data/lazy_imports/dunder_lazy_import_used.py
new file mode 100644
index 00000000000..635828b50ef
--- /dev/null
+++ b/Lib/test/test_import/data/lazy_imports/dunder_lazy_import_used.py
@@ -0,0 +1,2 @@
+basic = __lazy_import__('test.test_import.data.lazy_imports', fromlist="basic2")
+basic