From a69d40fc5dcbe2e3e51d4e1096e464d9f010c58b Mon Sep 17 00:00:00 2001
From: Isaac Corbrey <isaac@isaaccorbrey.com>
Date: Thu, 4 Dec 2025 10:06:41 -0500
Subject: [PATCH] [wip] day 4: Unload the printing department

---
 ...4_printing_department.proptest-regressions |  7 ++
 examples/day_04_printing_department.rs        | 76 +++++++++++++++++++
 2 files changed, 83 insertions(+)
 create mode 100644 examples/day_04_printing_department.proptest-regressions
 create mode 100644 examples/day_04_printing_department.rs

diff --git a/examples/day_04_printing_department.proptest-regressions b/examples/day_04_printing_department.proptest-regressions
new file mode 100644
index 0000000..595d307
--- /dev/null
+++ b/examples/day_04_printing_department.proptest-regressions
@@ -0,0 +1,7 @@
+# Seeds for failure cases proptest has generated in the past. It is
+# automatically read and these particular cases re-run before any
+# novel cases are generated.
+#
+# It is recommended to check this file in to source control so that
+# everyone who runs the test benefits from these saved cases.
+cc 2ede2633c7d67ab5e546e5c8c737e0b2a7033d69097fce43336250232de3eebb # shrinks to ch = ' '
diff --git a/examples/day_04_printing_department.rs b/examples/day_04_printing_department.rs
new file mode 100644
index 0000000..5b2a0fc
--- /dev/null
+++ b/examples/day_04_printing_department.rs
@@ -0,0 +1,76 @@
+fn main() {}
+
+#[derive(Debug)]
+struct Position {
+    x: u32,
+    y: u32,
+}
+
+fn is_paper_roll(ch: char) -> bool {
+    ch == '@'
+}
+
+fn parse_line(line: &str, y: u32) -> Vec<Position> {
+    vec![]
+}
+
+fn parse_input(input: &str) -> Vec<Position> {
+    vec![]
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use proptest::prelude::*;
+
+    mod is_paper_roll {
+        use super::*;
+
+        proptest! {
+            #[test]
+            fn doesnt_crash(ch in any::<char>()) {
+                is_paper_roll(ch);
+            }
+        }
+
+        #[test]
+        fn accepts_at_signs() {
+            assert!(is_paper_roll('@'));
+        }
+
+        proptest! {
+            #[test]
+            fn rejects_not_at_signs(ch in any::<char>().prop_filter("cannot be @", |ch| ch != &'@')) {
+                prop_assert!(!is_paper_roll(ch))
+            }
+        }
+    }
+
+    prop_compose! {
+        fn line(y: u32)(xs in prop::collection::vec(0_u32..100, 10..50)) -> Vec<Position> {
+            xs.iter().map(|x| Position { x: *x, y }).collect::<Vec<_>>()
+        }
+    }
+
+    mod parse_line {
+        use super::*;
+
+        // proptest! {
+        //     #[test]
+        //     fn doesnt_crash(s in line(y), y in any::<u32>()) {
+        //         parse_line(&s, y);
+        //     }
+        // }
+    }
+
+    mod parse_input {
+        use super::*;
+
+        proptest! {
+            #[test]
+            fn doesnt_crash(s in "\\PC+") {
+                parse_input(&s);
+            }
+        }
+    }
+}
-- 
2.51.2