Reduce visibility of CaptureStdErr type to avoid warnings on older toolchains.

tests/test_class_attributes.rs

@@ -1,6 +1,6 @@
 #![cfg(feature = "macros")]
 
-use pyo3::{prelude::*, types::PyString};
+use pyo3::prelude::*;
 
 mod common;
 
@@ -98,37 +98,7 @@ fn recursive_class_attributes() {
 #[test]
 #[cfg(panic = "unwind")]
 fn test_fallible_class_attribute() {
-    use pyo3::exceptions::PyValueError;
-
-    #[pyclass]
-    struct BrokenClass;
-
-    #[pymethods]
-    impl BrokenClass {
-        #[classattr]
-        fn fails_to_init() -> PyResult<i32> {
-            Err(PyValueError::new_err("failed to create class attribute"))
-        }
-    }
-
-    Python::with_gil(|py| {
-        let stderr = CaptureStdErr::new(py).unwrap();
-        assert!(std::panic::catch_unwind(|| py.get_type::<BrokenClass>()).is_err());
-        assert_eq!(
-            stderr.reset().unwrap().trim(),
-            "\
-ValueError: failed to create class attribute
-
-The above exception was the direct cause of the following exception:
-
-RuntimeError: An error occurred while initializing `BrokenClass.fails_to_init`
-
-The above exception was the direct cause of the following exception:
-
-RuntimeError: An error occurred while initializing class BrokenClass"
-        )
-    })
-}
+    use pyo3::{exceptions::PyValueError, types::PyString};
 
     struct CaptureStdErr<'py> {
         oldstderr: &'py PyAny,
@@ -161,3 +131,33 @@ impl<'py> CaptureStdErr<'py> {
             Ok(payload)
         }
     }
+
+    #[pyclass]
+    struct BrokenClass;
+
+    #[pymethods]
+    impl BrokenClass {
+        #[classattr]
+        fn fails_to_init() -> PyResult<i32> {
+            Err(PyValueError::new_err("failed to create class attribute"))
+        }
+    }
+
+    Python::with_gil(|py| {
+        let stderr = CaptureStdErr::new(py).unwrap();
+        assert!(std::panic::catch_unwind(|| py.get_type::<BrokenClass>()).is_err());
+        assert_eq!(
+            stderr.reset().unwrap().trim(),
+            "\
+ValueError: failed to create class attribute
+
+The above exception was the direct cause of the following exception:
+
+RuntimeError: An error occurred while initializing `BrokenClass.fails_to_init`
+
+The above exception was the direct cause of the following exception:
+
+RuntimeError: An error occurred while initializing class BrokenClass"
+        )
+    });
+}