SignedHeader should contain commit (#42)

* Add commit to SignedHeader type and rename LastCommit to Commit:

 - Commit needed for lite client and RPC endpoint
 - Commit does not always refer to the last commit

* Move integration tests into tendermint; otherwise fixture tests won't run

* fmt

* verify some assumptions on the structure of the response

* Update tendermint/src/block/commit.rs

tendermint/src/block.rs

@@ -9,7 +9,7 @@ pub mod parts;
 mod size;
 
 pub use self::{
-    commit::LastCommit,
+    commit::Commit,
     header::Header,
     height::*,
     id::{Id, ParseId},
@@ -35,5 +35,5 @@ pub struct Block {
     pub evidence: evidence::Data,
 
     /// Last commit
-    pub last_commit: LastCommit,
+    pub last_commit: Commit,
 }

tendermint/src/block/commit.rs

@@ -4,11 +4,12 @@ use crate::{block, Vote};
 use serde::{Deserialize, Serialize};
 use std::{ops::Deref, slice};
 
-/// Last commit to a particular blockchain: +2/3 precommit signatures.
+/// Commit contains the justification (ie. a set of signatures) that a block was committed by a set of validators.
 ///
+/// <https://github.com/tendermint/tendermint/blob/51dc810d041eaac78320adc6d53ad8b160b06601/types/block.go#L486-L502>
 /// <https://github.com/tendermint/tendermint/blob/master/docs/spec/blockchain/blockchain.md#lastcommit>
 #[derive(Serialize, Deserialize, Clone, Debug)]
-pub struct LastCommit {
+pub struct Commit {
     /// Block ID of the last commit
     pub block_id: block::Id,
 

tendermint/src/rpc/endpoint/commit.rs

@@ -2,7 +2,6 @@
 
 use crate::{block, rpc};
 use serde::{Deserialize, Serialize};
-use std::ops::Deref;
 
 /// Get commit information about a specific block
 #[derive(Clone, Debug, Default, Deserialize, Eq, PartialEq, Serialize)]
@@ -44,12 +43,6 @@ impl rpc::Response for Response {}
 pub struct SignedHeader {
     /// Block header
     pub header: block::Header,
-}
-
-impl Deref for SignedHeader {
-    type Target = block::Header;
-
-    fn deref(&self) -> &block::Header {
-        &self.header
-    }
+    /// Commit containing signatures for the header
+    pub commit: block::Commit,
 }

tests/rpc.rs → tendermint/tests/rpc.rs

@@ -163,6 +163,12 @@ mod endpoints {
         let response = endpoint::commit::Response::from_json(&read_json_fixture("commit")).unwrap();
         let header = response.signed_header.header;
         assert_eq!(header.chain_id.as_ref(), EXAMPLE_CHAIN);
+        // For now we just want to make sure the commit including precommits and a block_id exist
+        // in SignedHeader; later we should verify some properties: e.g. block_id.hash matches the
+        // header etc:
+        let commit = response.signed_header.commit;
+        let _block_id = commit.block_id;
+        let _precommits = commit.precommits;
     }
 
     #[test]