GPL palette support; dedupe mock palette

src/palette.rs

@@ -56,6 +56,39 @@ impl Palette {
 
         format!("JASC-PAL\r\n0100\r\n{}\r\n{}\r\n", self.colours.len(), colours.join("\r\n"))
     }
+
+    /// GIMP .gpl format
+    pub fn from_gpl(path: PathBuf) -> Self {
+        let name = path.file_stem().unwrap().to_str().unwrap().into();
+
+        let mut colours = Vec::new();
+
+        for (index, line) in read_to_string(&path).unwrap().lines().enumerate() {
+            // ignore header and comments
+            if index > 0 && !line.starts_with("#") {
+                let parts = line.split_whitespace();
+                colours.push(Colour::from(parts.last().unwrap()));
+            }
+        }
+
+        Self { name, colours }
+    }
+
+    /// GIMP .gpl format
+    pub fn to_gpl(&self) -> String {
+        let colours: Vec<String> = self.colours.iter().map(|colour| {
+            format!(
+                "{}\t{}\t{}\t{}",
+                colour.red,
+                colour.green,
+                colour.blue,
+                colour.to_string().replace('#', "")
+            )
+        }).collect();
+
+        // todo re-insert original comments
+        format!("GIMP Palette\r\n{}\r\n", colours.join("\r\n"))
+    }
 }
 
 /// for toml purposes
@@ -111,27 +144,28 @@ mod test {
 
     #[test]
     fn palette_to_jasc() {
-        let output = Palette {
-            name: "soup11".into(),
-            colours: vec![
-                Colour { red: 79, green: 30, blue: 69 },
-                Colour { red: 150, green: 48, blue: 87 },
-                Colour { red: 215, green: 68, blue: 89 },
-                Colour { red: 235, green: 112, blue: 96 },
-                Colour { red: 255, green: 179, blue: 131 },
-                Colour { red: 255, green: 255, blue: 255 },
-                Colour { red: 127, green: 227, blue: 187 },
-                Colour { red: 92, green: 187, blue: 196 },
-                Colour { red: 69, green: 126, blue: 163 },
-                Colour { red: 56, green: 66, blue: 118 },
-                Colour { red: 50, green: 36, blue: 81 }
-            ]
-        }.to_jasc();
-
+        let output = crate::mock::palette::soup11().to_jasc();
         let expected = include_str!("test-resources/basic/palettes/soup11.pal");
         assert_eq!(output, expected);
     }
 
+    #[test]
+    fn palette_from_gpl() {
+        let path = PathBuf::from("src/test-resources/basic/palettes/soup11.gpl");
+        let output = Palette::from_gpl(path);
+        let expected = crate::mock::palette::soup11();
+
+        assert_eq!(output, expected);
+    }
+
+    #[test]
+    fn palette_to_gpl() {
+        let output = crate::mock::palette::soup11().to_gpl();
+        let expected = include_str!("test-resources/basic/palettes/soup11.gpl");
+
+        assert_eq!(output, expected);
+    }
+
     #[test]
     fn palette_from_toml() {
         let output = Palette::from(