Add tests for task 1 and 2

src/block.rs

@@ -1,3 +1,5 @@
+use std::ops;
+
 use Result;
 use binread::BinReadable;
 
@@ -45,6 +47,14 @@ impl Block {
     }
 }
 
+impl ops::Index<usize> for Block {
+    type Output = u8;
+
+    fn index(&self, index: usize) -> &<Self as ops::Index<usize>>::Output {
+        return &self.source[index];
+    }
+}
+
 impl BinReadable for Block {
     fn get(&mut self) -> Result<u8> {
         if self.pointer >= self.length {