diff --git a/.gitignore b/.gitignore
index 6fd4b5c..458a18e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,4 @@
 flamegraph.svg
 perf.data*
 out
+proptest-regressions
diff --git a/Cargo.lock b/Cargo.lock
index 57ecc36..3a07ba6 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -186,6 +186,21 @@ version = "0.21.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9d297deb1925b89f2ccc13d7635fa0714f12c87adce1c75356b39ca9b7178567"
 
+[[package]]
+name = "bit-set"
+version = "0.5.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0700ddab506f33b20a03b13996eccd309a48e5ff77d0d95926aa0210fb4e95f1"
+dependencies = [
+ "bit-vec",
+]
+
+[[package]]
+name = "bit-vec"
+version = "0.6.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "349f9b6a179ed607305526ca489b34ad0a41aed5f7980fa90eb03160b69598fb"
+
 [[package]]
 name = "bit_field"
 version = "0.10.2"
@@ -481,6 +496,8 @@ dependencies = [
  "flate2",
  "image",
  "miette",
+ "proptest",
+ "proptest-derive",
  "rand",
  "serde",
  "serde_json",
@@ -488,6 +505,12 @@ dependencies = [
  "termcolor",
 ]
 
+[[package]]
+name = "fastrand"
+version = "2.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e8c02a5121d4ea3eb16a80748c74f5549a5665e4c21333c6098f283870fbdea6"
+
 [[package]]
 name = "fdeflate"
 version = "0.3.4"
@@ -516,6 +539,12 @@ dependencies = [
  "spin",
 ]
 
+[[package]]
+name = "fnv"
+version = "1.0.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3f9eec918d3f24069decb9af1554cad7c880e2da24a9afd88aca000531ab82c1"
+
 [[package]]
 name = "getrandom"
 version = "0.2.15"
@@ -610,7 +639,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f79afb8cbee2ef20f59ccd477a218c12a93943d075b492015ecb1bb81f8ee904"
 dependencies = [
  "byteorder-lite",
- "quick-error",
+ "quick-error 2.0.1",
 ]
 
 [[package]]
@@ -729,6 +758,12 @@ dependencies = [
  "once_cell",
 ]
 
+[[package]]
+name = "libm"
+version = "0.2.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4ec2a862134d2a7d32d7983ddcdd1c4923530833c9f2ea1a44fc5fa473989058"
+
 [[package]]
 name = "linux-raw-sys"
 version = "0.4.14"
@@ -901,6 +936,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "071dfc062690e90b734c0b2273ce72ad0ffa95f0c74596bc250dcfd960262841"
 dependencies = [
  "autocfg",
+ "libm",
 ]
 
 [[package]]
@@ -1020,6 +1056,37 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "proptest"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b4c2511913b88df1637da85cc8d96ec8e43a3f8bb8ccb71ee1ac240d6f3df58d"
+dependencies = [
+ "bit-set",
+ "bit-vec",
+ "bitflags 2.6.0",
+ "lazy_static",
+ "num-traits",
+ "rand",
+ "rand_chacha",
+ "rand_xorshift",
+ "regex-syntax",
+ "rusty-fork",
+ "tempfile",
+ "unarray",
+]
+
+[[package]]
+name = "proptest-derive"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6ff7ff745a347b87471d859a377a9a404361e7efc2a971d73424a6d183c0fc77"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "qoi"
 version = "0.4.1"
@@ -1029,6 +1096,12 @@ dependencies = [
  "bytemuck",
 ]
 
+[[package]]
+name = "quick-error"
+version = "1.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a1d01941d82fa2ab50be1e79e6714289dd7cde78eba4c074bc5a4374f650dfe0"
+
 [[package]]
 name = "quick-error"
 version = "2.0.1"
@@ -1074,6 +1147,15 @@ dependencies = [
  "getrandom",
 ]
 
+[[package]]
+name = "rand_xorshift"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d25bf25ec5ae4a3f1b92f929810509a2f53d7dca2f50b794ff57e3face536c8f"
+dependencies = [
+ "rand_core",
+]
+
 [[package]]
 name = "rav1e"
 version = "0.7.1"
@@ -1118,7 +1200,7 @@ dependencies = [
  "avif-serialize",
  "imgref",
  "loop9",
- "quick-error",
+ "quick-error 2.0.1",
  "rav1e",
  "rgb",
 ]
@@ -1200,6 +1282,18 @@ dependencies = [
  "windows-sys 0.52.0",
 ]
 
+[[package]]
+name = "rusty-fork"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cb3dcc6e454c328bb824492db107ab7c0ae8fcffe4ad210136ef014458c1bc4f"
+dependencies = [
+ "fnv",
+ "quick-error 1.2.3",
+ "tempfile",
+ "wait-timeout",
+]
+
 [[package]]
 name = "ryu"
 version = "1.0.18"
@@ -1384,6 +1478,19 @@ version = "0.12.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "61c41af27dd6d1e27b1b16b489db798443478cef1f06a660c96db617ba5de3b1"
 
+[[package]]
+name = "tempfile"
+version = "3.12.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "04cbcdd0c794ebb0d4cf35e88edd2f7d2c4c3e9a5a6dab322839b321c6a87a64"
+dependencies = [
+ "cfg-if",
+ "fastrand",
+ "once_cell",
+ "rustix",
+ "windows-sys 0.59.0",
+]
+
 [[package]]
 name = "termcolor"
 version = "1.4.1"
@@ -1498,6 +1605,12 @@ dependencies = [
  "winnow",
 ]
 
+[[package]]
+name = "unarray"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "eaea85b334db583fe3274d12b4cd1880032beab409c0d774be044d4480ab9a94"
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.13"
@@ -1545,6 +1658,15 @@ version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "852e951cb7832cb45cb1169900d19760cfa39b82bc0ea9c0e5a14ae88411c98b"
 
+[[package]]
+name = "wait-timeout"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9f200f5b12eb75f8c1ed65abd4b2db8a6e1b138a20de009dacee265a2498f3f6"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "walkdir"
 version = "2.5.0"
diff --git a/Cargo.toml b/Cargo.toml
index 88b63fd..ea2dcc9 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -21,6 +21,8 @@ clap = { version = "4.4.8", features = ["derive"] }
 flate2 = "1.0.28"
 image = "0.25.2"
 miette = { version = "7.2.0", features = ["fancy"] }
+proptest = "1.5.0"
+proptest-derive = "0.5.0"
 rand = { version = "0.8.5", features = ["small_rng"] }
 serde = { version = "1.0.192", features = ["derive"] }
 serde_json = "1.0.108"
diff --git a/src/common/block.rs b/src/common/block.rs
index 74644fd..a3e893b 100644
--- a/src/common/block.rs
+++ b/src/common/block.rs
@@ -60,6 +60,7 @@ impl Transformable for Block {
 #[cfg(test)]
 mod test {
     use super::*;
+    use proptest::{prop_assert_eq, proptest};
 
     #[test]
     fn transformations() {
@@ -76,18 +77,18 @@ mod test {
         assert_eq!(m, Position::new(8, 8));
     }
 
-    #[test]
-    fn identity_transformation() {
-        let b = Block::new(Position::new(10, 5), Direction::Right, Position::new(4, 3));
+    proptest! {
+        #[test]
+        fn identity_transformation(dir: Direction, pos: Position, size: Position) {
+            let b = Block::new(pos, dir, size);
 
-        let t = b.world_to_block();
+            let t = b.world_to_block();
 
-        let n = b.transform(t);
+            let n = b.transform(t);
 
-        dbg!(t, n);
-
-        assert_eq!(n.dir, Direction::Up);
-        assert_eq!(n.pos, Position::new(0, 0));
-        assert_eq!(n.size, Position::new(4, 3));
+            prop_assert_eq!(n.dir, Direction::Up);
+            prop_assert_eq!(n.pos, Position::new(0, 0));
+            prop_assert_eq!(n.size, size);
+        }
     }
 }
diff --git a/src/common/direction.rs b/src/common/direction.rs
index 64bc546..bef4b06 100644
--- a/src/common/direction.rs
+++ b/src/common/direction.rs
@@ -2,6 +2,7 @@ use crate::prelude::*;
 use serde::{Deserialize, Serialize};
 
 #[derive(Clone, Copy, PartialEq, Eq, Debug, Hash, Deserialize, Serialize)]
+#[cfg_attr(test, derive(proptest_derive::Arbitrary))]
 pub enum Direction {
     Up,
     Right,
diff --git a/src/common/position.rs b/src/common/position.rs
index 56014b4..dcdc5ca 100644
--- a/src/common/position.rs
+++ b/src/common/position.rs
@@ -4,6 +4,7 @@ use serde::{Deserialize, Serialize};
 pub type PositionType = i32;
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Deserialize, Serialize)]
+#[cfg_attr(test, derive(proptest_derive::Arbitrary))]
 pub struct Position {
     pub x: PositionType,
     pub y: PositionType,
diff --git a/src/common/transformation.rs b/src/common/transformation.rs
index 63f3a4d..1e97ac8 100644
--- a/src/common/transformation.rs
+++ b/src/common/transformation.rs
@@ -75,6 +75,7 @@ impl Transformable for Direction {
 #[cfg(test)]
 mod test {
     use crate::prelude::*;
+    use proptest::{prop_assert_eq, proptest};
 
     #[test]
     fn position() {
@@ -87,21 +88,16 @@ mod test {
         assert_eq!(p.transform(t), Position::new(-6, -10));
     }
 
-    #[test]
-    fn invert() {
-        let transformations = [
-            Transformation::new(Direction::Up, Position::new(-3, -5)),
-            Transformation::new(Direction::Right, Position::new(-3, -5)),
-            Transformation::new(Direction::Down, Position::new(-3, -5)),
-            Transformation::new(Direction::Left, Position::new(-3, -5)),
-        ];
+    proptest! {
+        #[test]
+        fn invert(dir: Direction, pos: Position) {
+            let o = Transformation::new(dir, pos);
 
-        for o in transformations {
             let i = o.invert();
             let c = o.chain(i);
 
-            assert_eq!(c.rot, Direction::Up, "o: {:?}, i: {:?}, c: {:?}", o, i, c);
-            assert_eq!(
+            prop_assert_eq!(c.rot, Direction::Up, "o: {:?}, i: {:?}, c: {:?}", o, i, c);
+            prop_assert_eq!(
                 c.pos,
                 Position::new(0, 0),
                 "o: {:?}, i: {:?}, c: {:?}",
@@ -109,6 +105,7 @@ mod test {
                 i,
                 c
             );
+
         }
     }
 }