chore: Add tests to check invalid pointer error result

Author: jhg

src/error.rs

@@ -6,7 +6,7 @@ use std::str::Utf8Error;
 ///
 /// Of course, invalid address can not be detected, then it's unsafe yet.
 #[allow(clippy::module_name_repetitions)] // Like std::error::Error, it is for pointer errors
-#[derive(Debug)]
+#[derive(Debug, PartialEq, Eq)]
 pub enum PointerError {
     #[allow(missing_docs)] // Obviously, the name is the ref doc.
     Null,

tests/pointer.rs

@@ -1,5 +1,6 @@
 use opaque_pointer;
 
+#[derive(Debug)]
 struct TestIt {
     value: u8,
 }
@@ -23,6 +24,17 @@ fn own_back() {
     assert_eq!(test_it.get(), 2);
 }
 
+#[cfg(all(feature = "std", feature = "lender"))]
+#[test]
+fn own_back_invalid_pointer() {
+    let pointer = Box::into_raw(Box::new(TestIt::new(2)));
+    let invalid_pointer_error = unsafe { opaque_pointer::own_back(pointer).unwrap_err() };
+    assert_eq!(
+        invalid_pointer_error,
+        opaque_pointer::error::PointerError::Invalid
+    );
+}
+
 #[test]
 fn immutable_reference() {
     let pointer = opaque_pointer::raw(TestIt::new(2));
@@ -31,6 +43,17 @@ fn immutable_reference() {
     unsafe { opaque_pointer::own_back(pointer).unwrap() };
 }
 
+#[cfg(all(feature = "std", feature = "lender"))]
+#[test]
+fn immutable_reference_invalid_pointer() {
+    let pointer = Box::into_raw(Box::new(TestIt::new(2)));
+    let invalid_pointer_error = unsafe { opaque_pointer::object(pointer).unwrap_err() };
+    assert_eq!(
+        invalid_pointer_error,
+        opaque_pointer::error::PointerError::Invalid
+    );
+}
+
 #[test]
 fn mutable_reference() {
     let pointer = opaque_pointer::raw(TestIt::new(2));
@@ -39,3 +62,14 @@ fn mutable_reference() {
     assert_eq!(object.get(), 5);
     unsafe { opaque_pointer::own_back(pointer).unwrap() };
 }
+
+#[cfg(all(feature = "std", feature = "lender"))]
+#[test]
+fn mutable_reference_invalid_pointer() {
+    let pointer = Box::into_raw(Box::new(TestIt::new(2)));
+    let invalid_pointer_error = unsafe { opaque_pointer::mut_object(pointer).unwrap_err() };
+    assert_eq!(
+        invalid_pointer_error,
+        opaque_pointer::error::PointerError::Invalid
+    );
+}