Add quickcheck tests for from_slices

...and also a property based test for the normal roundtrip,
now that we have the dependency anyway.

Author: rklaehn

Cargo.toml

@@ -24,3 +24,6 @@ sha1 = "0.5"
 sha2 = { version = "0.7", default-features = false }
 tiny-keccak = "1.4"
 unsigned-varint = "0.3"
+
+[dev-dependencies]
+quickcheck = "0.9.2"

src/lib.rs

@@ -25,6 +25,10 @@ pub use hashes::Hash;
 use std::fmt;
 use storage::Storage;
 
+#[cfg(test)]
+#[macro_use]
+extern crate quickcheck;
+
 // Helper macro for encoding input into output using sha1, sha2, tiny_keccak, or blake2
 macro_rules! encode {
     (sha1, Sha1, $input:expr, $output:expr) => {{

src/storage.rs

@@ -62,6 +62,7 @@ impl Storage {
 #[cfg(test)]
 mod tests {
     use super::{Storage, MAX_INLINE};
+    use quickcheck;
 
     #[test]
     fn struct_size() {
@@ -78,4 +79,22 @@ mod tests {
             assert_eq!(data, storage.bytes());
         }
     }
+
+    quickcheck! {
+        fn roundtrip_check(data: Vec<u8>) -> bool {
+            let storage = Storage::from_slice(&data);
+            storage.bytes() == data.as_slice()
+        }
+
+        fn from_slices_roundtrip_check(data: Vec<Vec<u8>>) -> bool {
+            let mut slices = Vec::new();
+            let mut expected = Vec::new();
+            for v in data.iter() {
+                slices.push(v.as_slice());
+                expected.extend_from_slice(&v);
+            }
+            let storage = Storage::from_slices(&slices);
+            storage.bytes() == expected.as_slice()
+        }
+    }
 }