Merge pull request #307 from PyO3/missing-debug-impls

Add missing implementations of the Debug trait for the borrow checking wrapper types.

Author: adamreichold

src/borrow.rs

@@ -161,8 +161,10 @@
 //! [base]: https://numpy.org/doc/stable/reference/c-api/types-and-structures.html#c.NPY_AO.base
 #![deny(missing_docs)]
 
+use std::any::type_name;
 use std::cell::UnsafeCell;
 use std::collections::hash_map::{Entry, HashMap};
+use std::fmt;
 use std::mem::size_of;
 use std::ops::Deref;
 
@@ -500,6 +502,22 @@ where
     }
 }
 
+impl<'py, T, D> fmt::Debug for PyReadonlyArray<'py, T, D>
+where
+    T: Element,
+    D: Dimension,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let name = format!(
+            "PyReadonlyArray<{}, {}>",
+            type_name::<T>(),
+            type_name::<D>()
+        );
+
+        f.debug_struct(&name).finish()
+    }
+}
+
 /// Read-write borrow of an array.
 ///
 /// An instance of this type ensures that there are no instances of [`PyReadonlyArray`] and no other instances of [`PyReadwriteArray`],
@@ -636,6 +654,22 @@ where
     }
 }
 
+impl<'py, T, D> fmt::Debug for PyReadwriteArray<'py, T, D>
+where
+    T: Element,
+    D: Dimension,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let name = format!(
+            "PyReadwriteArray<{}, {}>",
+            type_name::<T>(),
+            type_name::<D>()
+        );
+
+        f.debug_struct(&name).finish()
+    }
+}
+
 fn base_address<T, D>(array: &PyArray<T, D>) -> usize {
     let py = array.py();
     let mut array = array.as_array_ptr();
@@ -1210,4 +1244,29 @@ mod tests {
             }
         });
     }
+
+    #[test]
+    fn test_debug_formatting() {
+        Python::with_gil(|py| {
+            let array = PyArray::<f64, _>::zeros(py, (1, 2, 3), false);
+
+            {
+                let shared = array.readonly();
+
+                assert_eq!(
+                    format!("{:?}", shared),
+                    "PyReadonlyArray<f64, ndarray::dimension::dim::Dim<[usize; 3]>>"
+                );
+            }
+
+            {
+                let exclusive = array.readwrite();
+
+                assert_eq!(
+                    format!("{:?}", exclusive),
+                    "PyReadwriteArray<f64, ndarray::dimension::dim::Dim<[usize; 3]>>"
+                );
+            }
+        });
+    }
 }

tests/borrow.rs

@@ -55,18 +55,18 @@ fn shared_and_exclusive_borrows() {
 }
 
 #[test]
-#[should_panic(expected = "AlreadyBorrowed")]
 fn multiple_exclusive_borrows() {
     Python::with_gil(|py| {
         let array = PyArray::<f64, _>::zeros(py, (1, 2, 3), false);
 
-        let _exclusive1 = array.readwrite();
-        let _exclusive2 = array.readwrite();
+        let _exclusive = array.try_readwrite().unwrap();
+
+        let err = array.try_readwrite().unwrap_err();
+        assert_eq!(err.to_string(), "The given array is already borrowed");
     });
 }
 
 #[test]
-#[should_panic(expected = "NotWriteable")]
 fn exclusive_borrow_requires_writeable() {
     Python::with_gil(|py| {
         let array = PyArray::<f64, _>::zeros(py, (1, 2, 3), false);
@@ -75,7 +75,8 @@ fn exclusive_borrow_requires_writeable() {
             (*array.as_array_ptr()).flags &= !NPY_ARRAY_WRITEABLE;
         }
 
-        let _exclusive = array.readwrite();
+        let err = array.try_readwrite().unwrap_err();
+        assert_eq!(err.to_string(), "The given array is not writeable");
     });
 }