proptest reveals that dsl breaks at invalid char boundaries

output/src/op_bsp.rs

@@ -116,3 +116,28 @@ impl<E: Output, A: Content<E>, B: Content<E>> BspAreas<E, A, B> for Bsp<A, B> {
 #[macro_export] macro_rules! row {
     ($($expr:expr),* $(,)?) => {{ let bsp = (); $(let bsp = Bsp::e(bsp, $expr);)*; bsp }};
 }
+#[cfg(test)] mod test {
+    use super::*;
+    use proptest::prelude::*;
+    proptest! {
+        #[test] fn proptest_op_bsp (
+            d in prop_oneof![
+                Just(North), Just(South),
+                Just(East),  Just(West),
+                Just(Above), Just(Below)
+            ],
+            a in "\\PC*",
+            b in "\\PC*",
+            x in u16::MIN..u16::MAX,
+            y in u16::MIN..u16::MAX,
+            w in u16::MIN..u16::MAX,
+            h in u16::MIN..u16::MAX,
+        ) {
+            let bsp = Bsp(d, a, b);
+            assert_eq!(
+                Content::layout(&bsp, [x, y, w, h]),
+                Render::layout(&bsp, [x, y, w, h]),
+            );
+        }
+    }
+}