Add a basic test.

This ran into problems with Clone/Copy bounds -- it seems like the
derived impls require that the phantom type T also be Clone / Copy /
Debug for the type to be.  This commit does a hacky fix that makes it
work for now, but it should be cleaned up later.

Cargo.toml

@@ -10,5 +10,8 @@ thiserror = "1.0"
 blake2b_simd = "0.5"
 jubjub = { git = "https://github.com/zkcrypto/jubjub", rev = "e83f7d2bd136498a27f9d943fea635d8682bf2c6" }
 
+[dev-dependencies]
+rand = "0.7"
+
 [features]
 nightly = []

src/lib.rs

@@ -39,16 +39,18 @@ pub use signature::Signature;
 pub trait SigType: private::Sealed {}
 
 /// A type variable corresponding to Zcash's `BindingSig`.
+#[derive(Copy, Clone, Debug)]
 pub struct Binding {}
 impl SigType for Binding {}
 
 /// A type variable corresponding to Zcash's `SpendAuthSig`.
+#[derive(Copy, Clone, Debug)]
 pub struct SpendAuth {}
 impl SigType for SpendAuth {}
 
 pub(crate) mod private {
     use super::*;
-    pub trait Sealed {
+    pub trait Sealed: Copy + Clone + std::fmt::Debug {
         fn basepoint() -> jubjub::ExtendedPoint;
     }
     impl Sealed for Binding {
@@ -66,3 +68,18 @@ pub(crate) mod private {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn sign_and_verify() {
+        let sk = SecretKey::<Binding>::new(rand::thread_rng());
+        let msg = b"test";
+        let sig = sk.sign(rand::thread_rng(), msg);
+        let pk = PublicKey::from(&sk);
+
+        assert_eq!(pk.verify(msg, &sig), Ok(()));
+    }
+}