improve coverage of Py2 trait implementations

src/instance.rs

@@ -1137,7 +1137,8 @@ where
 {
     #[inline]
     fn from(other: Py2<'_, T>) -> Self {
-        unsafe { Self::from_non_null(other.into_non_null()) }
+        let py = other.py();
+        other.into_py(py)
     }
 }
 
@@ -1335,7 +1336,7 @@ impl PyObject {
 
 #[cfg(test)]
 mod tests {
-    use super::{Py, PyObject};
+    use super::{Py, Py2, PyObject};
     use crate::types::{PyDict, PyString};
     use crate::{PyAny, PyResult, Python, ToPyObject};
 
@@ -1451,6 +1452,27 @@ a = A()
         })
     }
 
+    #[test]
+    fn test_py2_from_py_object() {
+        Python::with_gil(|py| {
+            let instance: &PyAny = py.eval("object()", None, None).unwrap();
+            let ptr = instance.as_ptr();
+            let instance: Py2<'_, PyAny> = instance.extract().unwrap();
+            assert_eq!(instance.as_ptr(), ptr);
+        })
+    }
+
+    #[test]
+    fn test_py2_into_py_object() {
+        Python::with_gil(|py| {
+            let instance: Py2<'_, PyAny> =
+                Py2::borrowed_from_gil_ref(&py.eval("object()", None, None).unwrap()).clone();
+            let ptr = instance.as_ptr();
+            let instance: PyObject = instance.clone().into();
+            assert_eq!(instance.as_ptr(), ptr);
+        })
+    }
+
     #[test]
     fn test_is_ellipsis() {
         Python::with_gil(|py| {