Update irbuild-classes.test

Author: BobTheBuidler

mypyc/test-data/irbuild-classes.test

@@ -2686,3 +2686,25 @@ L0:
     r6 = PyObject_VectorcallMethod(r3, r5, 9223372036854775812, 0)
     keep_alive r2, self, key, val
     return 1
+
+[case testIsInstanceInterpretedSubclasses]
+from mypy_extensions import mypyc_attr
+
+@mypyc_attr(native_class=False)
+class NonNative:
+    pass
+@mypyc_attr(allow_interpreted_subclasses=True)
+class InterpSubclasses:
+    pass
+def isinstance_nonnative(x: Any) -> bool:
+    return isinstance(x, NonNative)
+def isinstance_interpreted_subclasses(x: Any) -> None:
+    return isinstance(x, InterpSubclasses)
+
+[out]
+def isinstance_nonnative(x):
+    x :: Any
+L0:
+def isinstance_interpreted_subclasses(x):
+    x :: Any
+L0: