Add tests for __lazy_import__

Author: DinoV

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.
 

Lib/test/test_import/data/lazy_imports/dunder_lazy_import.py

@@ -0,0 +1 @@
+basic = __lazy_import__('test.test_import.data.lazy_imports.basic2')

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

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