gh-130941: Fix `configparser` parsing values with `allow_no_value` and `interpolation` set (GH-130949)

1 files changed, 41 insertions, 0 deletions

diff --git a/Lib/test/test_configparser.py b/Lib/test/test_configparser.py
index 1313ec2..23904d1 100644
--- a/Lib/test/test_configparser.py
+++ b/Lib/test/test_configparser.py
@@ -1328,6 +1328,47 @@ class ConfigParserTestCaseNoValue(ConfigParserTestCase):
     allow_no_value = True
 
 
+class NoValueAndExtendedInterpolation(CfgParserTestCaseClass):
+    interpolation = configparser.ExtendedInterpolation()
+    allow_no_value = True
+
+    def test_interpolation_with_allow_no_value(self):
+        config = textwrap.dedent("""
+            [dummy]
+            a
+            b = ${a}
+        """)
+        cf = self.fromstring(config)
+
+        self.assertIs(cf["dummy"]["a"], None)
+        self.assertEqual(cf["dummy"]["b"], "")
+
+    def test_explicit_none(self):
+        config = textwrap.dedent("""
+            [dummy]
+            a = None
+            b = ${a}
+        """)
+        cf = self.fromstring(config)
+
+        self.assertEqual(cf["dummy"]["a"], "None")
+        self.assertEqual(cf["dummy"]["b"], "None")
+
+
+class ConfigParserNoValueAndExtendedInterpolationTest(
+    NoValueAndExtendedInterpolation,
+    unittest.TestCase,
+):
+    config_class = configparser.ConfigParser
+
+
+class RawConfigParserNoValueAndExtendedInterpolationTest(
+    NoValueAndExtendedInterpolation,
+    unittest.TestCase,
+):
+    config_class = configparser.RawConfigParser
+
+
 class ConfigParserTestCaseTrickyFile(CfgParserTestCaseClass, unittest.TestCase):
     config_class = configparser.ConfigParser
     delimiters = {'='}