Image is now mapped to a pixel-identical image

src/main.rs

@@ -70,7 +70,7 @@ fn save_image(width: usize, height: usize, image: Vec<Vec<u8>>) {
     assert_eq!(image.len(), 3);
 
     let mut encoder = png::Encoder::new(
-        File::create("outputs/avatar2.png").unwrap(),
+        File::create("outputs/avatar2_out.png").unwrap(),
         width as u32, height as u32, 
     );
     encoder.set_color(ColorType::Rgb);

src/transform.rs

@@ -37,4 +37,35 @@ fn transform(data: &mut [i32], zero: usize, stride: usize, divisor: i32) {
     for i in 0..TILE_SZ {
         data[ix(GRAY[i])] = row[i] / divisor;
     }
-}
+}
+
+#[cfg(test)]
+mod tests {
+    use quickcheck::{quickcheck, Arbitrary};
+
+    use crate::{constants::TILE_SZ, transform::{decode, encode}};
+
+    #[derive(Clone, Debug)]
+    struct Encodable { args: [i32; TILE_SZ] }
+
+    impl Arbitrary for Encodable {
+        fn arbitrary(g: &mut quickcheck::Gen) -> Self {
+            let mut args = [0; TILE_SZ];
+            for i in 0..TILE_SZ {
+                args[i] = i16::arbitrary(g) as i32;
+            }
+            return Encodable { args };
+        }
+    }
+
+    quickcheck! {
+        fn reversible(xs: Encodable) -> bool {
+            let orig = xs.args;
+            let mut enc = orig.clone();
+            encode(&mut enc, 0, 1);
+            let mut dec = enc.clone();
+            decode(&mut dec, 0, 1);
+            orig == dec
+        }
+    }
+}