feat: CommitRefIter::(author|committer)(), better usability (#364)

The methods returning an iterator are now consuming, which allows
them to be nested by callers.

Author: Byron

git-object/src/commit/ref_iter.rs

@@ -83,6 +83,24 @@ impl<'a> CommitRefIter<'a> {
             _ => None,
         })
     }
+
+    /// Returns the author signature if there is no decoding error.
+    /// Errors are coerced into options, hiding whether there was an error or not. The caller knows if there was an error or not.
+    pub fn author(&mut self) -> Option<git_actor::SignatureRef<'_>> {
+        self.find_map(|t| match t {
+            Ok(Token::Author { signature }) => Some(signature),
+            _ => None,
+        })
+    }
+
+    /// Returns the message if there is no decoding error.
+    /// Errors are coerced into options, hiding whether there was an error or not. The caller knows if there was an error or not.
+    pub fn message(&mut self) -> Option<&'a BStr> {
+        self.find_map(|t| match t {
+            Ok(Token::Message(msg)) => Some(msg),
+            _ => None,
+        })
+    }
 }
 
 impl<'a> CommitRefIter<'a> {

git-object/tests/immutable/commit/iter.rs

@@ -24,9 +24,10 @@ fn newline_right_after_signature_multiline_header() -> crate::Result {
 
 #[test]
 fn signed_with_encoding() -> crate::Result {
+    let input = fixture_bytes("commit", "signed-with-encoding.txt");
+    let mut iter = CommitRefIter::from_bytes(&input);
     assert_eq!(
-        CommitRefIter::from_bytes(&fixture_bytes("commit", "signed-with-encoding.txt"))
-            .collect::<Result<Vec<_>, _>>()?,
+        iter.collect::<Result<Vec<_>, _>>()?,
         vec![
             Token::Tree {
                 id: hex_to_id("1973afa74d87b2bb73fa884aaaa8752aec43ea88")
@@ -45,6 +46,9 @@ fn signed_with_encoding() -> crate::Result {
             Token::Message(b"encoding & sig".as_bstr()),
         ]
     );
+
+    assert_eq!(iter.author(), Some(signature(1592448995)));
+    assert_eq!(iter.committer(), Some(signature(1592449083)));
     Ok(())
 }
 
@@ -135,8 +139,10 @@ fn error_handling() -> crate::Result {
 
 #[test]
 fn mergetag() -> crate::Result {
+    let input = fixture_bytes("commit", "mergetag.txt");
+    let mut iter = CommitRefIter::from_bytes(&input);
     assert_eq!(
-        CommitRefIter::from_bytes(&fixture_bytes("commit", "mergetag.txt")).collect::<Result<Vec<_>, _>>()?,
+        iter.collect::<Result<Vec<_>, _>>()?,
         vec![
             Token::Tree {
                 id: hex_to_id("1c61918031bf2c7fab9e17dde3c52a6a9884fcb5")
@@ -154,18 +160,17 @@ fn mergetag() -> crate::Result {
                 signature: linus_signature(1591996221)
             },
             Token::ExtraHeader((b"mergetag".as_bstr(), MERGE_TAG.as_bytes().as_bstr().into())),
-            Token::Message(LONG_MESSAGE.as_bytes().as_bstr()),
+            Token::Message(LONG_MESSAGE.into()),
         ]
     );
     assert_eq!(
-        CommitRefIter::from_bytes(&fixture_bytes("commit", "mergetag.txt"))
-            .parent_ids()
-            .collect::<Vec<_>>(),
+        iter.parent_ids().collect::<Vec<_>>(),
         vec![
             hex_to_id("44ebe016df3aad96e3be8f95ec52397728dd7701"),
             hex_to_id("8d485da0ddee79d0e6713405694253d401e41b93")
         ]
     );
+    assert_eq!(iter.message(), Some(LONG_MESSAGE.into()));
     Ok(())
 }
 
@@ -179,33 +184,31 @@ mod method {
 
     #[test]
     fn tree_id() -> crate::Result {
+        let input = fixture_bytes("commit", "unsigned.txt");
+        let iter = CommitRefIter::from_bytes(&input);
         assert_eq!(
-            CommitRefIter::from_bytes(&fixture_bytes("commit", "unsigned.txt")).tree_id(),
+            iter.clone().tree_id(),
             Some(hex_to_id("1b2dfb4ac5e42080b682fc676e9738c94ce6d54d"))
         );
         assert_eq!(
-            CommitRefIter::from_bytes(&fixture_bytes("commit", "unsigned.txt"))
-                .signatures()
-                .collect::<Vec<_>>(),
+            iter.signatures().collect::<Vec<_>>(),
             vec![signature(1592437401), signature(1592437401)]
         );
-        assert_eq!(
-            CommitRefIter::from_bytes(&fixture_bytes("commit", "unsigned.txt"))
-                .parent_ids()
-                .count(),
-            0
-        );
+        assert_eq!(iter.parent_ids().count(), 0);
         Ok(())
     }
 
     #[test]
     fn signatures() -> crate::Result {
+        let input = fixture_bytes("commit", "unsigned.txt");
+        let mut iter = CommitRefIter::from_bytes(&input);
         assert_eq!(
-            CommitRefIter::from_bytes(&fixture_bytes("commit", "unsigned.txt"))
-                .signatures()
-                .collect::<Vec<_>>(),
+            iter.signatures().collect::<Vec<_>>(),
             vec![signature(1592437401), signature(1592437401)]
         );
+        assert_eq!(iter.author(), Some(signature(1592437401)));
+        assert_eq!(iter.committer(), Some(signature(1592437401)));
+        assert_eq!(iter.committer(), None, "it's consuming");
         Ok(())
     }
 }