proptest reveals that dsl breaks at invalid char boundaries

output/src/area.rs

@@ -96,7 +96,7 @@ impl<N: Coordinate> Area<N> for [N;4] {
     use super::*;
     use proptest::prelude::*;
     proptest! {
-        #[test] fn test_area (
+        #[test] fn test_area_prop (
             x in u16::MIN..u16::MAX,
             y in u16::MIN..u16::MAX,
             w in u16::MIN..u16::MAX,

output/src/direction.rs

@@ -1,6 +1,8 @@
 use crate::*;
+#[cfg(test)] use proptest_derive::Arbitrary;
 /// A cardinal direction.
-#[derive(Copy, Clone, PartialEq)]
+#[derive(Copy, Clone, PartialEq, Debug)]
+#[cfg_attr(test, derive(Arbitrary))]
 pub enum Direction { North, South, East, West, Above, Below }
 impl Direction {
     pub fn split_fixed <N: Coordinate> (self, area: impl Area<N>, a: N) -> ([N;4],[N;4]) {
@@ -14,20 +16,23 @@ impl Direction {
         }
     }
 }
-#[cfg(test)] mod test_op_transform {
+#[cfg(test)] mod test {
     use super::*;
     use proptest::prelude::*;
     proptest! {
-        #[test] fn test_direction (
+        #[test] fn proptest_direction (
+            d in prop_oneof![
+                Just(North), Just(South),
+                Just(East),  Just(West),
+                Just(Above), Just(Below)
+            ],
             x in u16::MIN..u16::MAX,
             y in u16::MIN..u16::MAX,
             w in u16::MIN..u16::MAX,
             h in u16::MIN..u16::MAX,
             a in u16::MIN..u16::MAX,
         ) {
-            for d in [North, South, East, West, Above, Below].iter() {
-                let _ = d.split_fixed([x, y, w, h], a);
-            }
+            let _ = d.split_fixed([x, y, w, h], a);
         }
     }
 }

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]),
+            );
+        }
+    }
+}