Add a really basic quickcheck

agb-image-converter/Cargo.toml

@@ -20,3 +20,6 @@ proc-macro2 = "1"
 quote = "1"
 asefile = "0.3.8"
 fontdue = "0.9"
+
+[dev-dependencies]
+quickcheck = "1"

agb-image-converter/src/colour.rs

@@ -38,3 +38,26 @@ impl FromStr for Colour {
         Ok(Colour::from_rgb(r, g, b, 255))
     }
 }
+
+#[cfg(test)]
+impl quickcheck::Arbitrary for Colour {
+    fn arbitrary(g: &mut quickcheck::Gen) -> Self {
+        Self::from_rgb(
+            quickcheck::Arbitrary::arbitrary(g),
+            quickcheck::Arbitrary::arbitrary(g),
+            quickcheck::Arbitrary::arbitrary(g),
+            quickcheck::Arbitrary::arbitrary(g),
+        )
+    }
+
+    fn shrink(&self) -> Box<dyn Iterator<Item = Self>> {
+        Box::new(
+            vec![
+                Colour::from_rgb(0, 0, 0, 0),
+                Colour::from_rgb(self.r, self.g, self.b, 0),
+                self.clone(),
+            ]
+            .into_iter(),
+        )
+    }
+}

agb-image-converter/src/palette16.rs

@@ -210,3 +210,36 @@ impl Palette16Optimiser {
         }
     }
 }
+
+#[cfg(test)]
+mod test {
+    use quickcheck::{quickcheck, Arbitrary};
+
+    use super::*;
+
+    quickcheck! {
+        fn less_than_256_colours_always_fits(palettes: Vec<Palette16>) -> () {
+            let mut optimiser = Palette16Optimiser::new(None);
+            for palette in palettes.into_iter().take(16) {
+                optimiser.add_palette(palette);
+            }
+
+            optimiser.optimise_palettes();
+        }
+    }
+
+    impl Arbitrary for Palette16 {
+        fn arbitrary(g: &mut quickcheck::Gen) -> Self {
+            let mut palette = Palette16::new();
+
+            let size: usize = Arbitrary::arbitrary(g);
+            let size = size.rem_euclid(16);
+
+            for _ in 0..size {
+                palette.add_colour(Arbitrary::arbitrary(g));
+            }
+
+            palette
+        }
+    }
+}