Update comment and add tests

Author: Letiste

Diff for: src/packbuilder.rs

@@ -87,9 +87,8 @@ impl<'repo> PackBuilder<'repo> {
         Ok(())
     }
 
-    /// Write the contents of the packfile to the specified path. The contents
-    /// of the buffer will become a valid packfile, even though there will be
-    /// no attached index.
+    /// Write the new pack and corresponding index file to path.
+    /// To set a progress callback, use `set_progress_callback` before calling this method.
     pub fn write(&mut self, path: &Path, mode: u32) -> Result<(), Error> {
         let path = path.into_c_string()?;
         let progress_cb: raw::git_indexer_progress_cb = Some(write_pack_progress_cb);
@@ -294,7 +293,10 @@ extern "C" fn progress_c(
 
 #[cfg(test)]
 mod tests {
-    use crate::Buf;
+    use crate::{Buf, Oid};
+
+    // hash of a packfile constructed without any objects in it
+    const EMPTY_PACKFILE_OID: &str = "029d08823bd8a8eab510ad6ac75c823cfd3ed31e";
 
     fn pack_header(len: u8) -> Vec<u8> {
         [].iter()
@@ -338,6 +340,18 @@ mod tests {
         assert_eq!(&*buf, &*empty_pack_header());
     }
 
+    #[test]
+    fn smoke_write() {
+        let (_td, repo) = crate::test::repo_init();
+        let mut builder = t!(repo.packbuilder());
+        t!(builder.write(repo.path(), 0));
+        #[allow(deprecated)]
+        {
+            assert!(builder.hash().unwrap() == Oid::from_str(EMPTY_PACKFILE_OID).unwrap());
+        }
+        assert!(builder.name().unwrap() == EMPTY_PACKFILE_OID);
+    }
+
     #[test]
     fn smoke_foreach() {
         let (_td, repo) = crate::test::repo_init();
@@ -391,6 +405,41 @@ mod tests {
         assert_eq!(&buf[0..12], &*pack_header(3));
     }
 
+    #[test]
+    fn insert_write() {
+        let (_td, repo) = crate::test::repo_init();
+        let mut builder = t!(repo.packbuilder());
+        let (commit, _tree) = crate::test::commit(&repo);
+        t!(builder.insert_object(commit, None));
+        assert_eq!(builder.object_count(), 1);
+        t!(builder.write(repo.path(), 0));
+        t!(repo.find_commit(commit));
+    }
+
+    #[test]
+    fn insert_tree_write() {
+        let (_td, repo) = crate::test::repo_init();
+        let mut builder = t!(repo.packbuilder());
+        let (_commit, tree) = crate::test::commit(&repo);
+        // will insert the tree itself and the blob, 2 objects
+        t!(builder.insert_tree(tree));
+        assert_eq!(builder.object_count(), 2);
+        t!(builder.write(repo.path(), 0));
+        t!(repo.find_tree(tree));
+    }
+
+    #[test]
+    fn insert_commit_write() {
+        let (_td, repo) = crate::test::repo_init();
+        let mut builder = t!(repo.packbuilder());
+        let (commit, _tree) = crate::test::commit(&repo);
+        // will insert the commit, its tree and the blob, 3 objects
+        t!(builder.insert_commit(commit));
+        assert_eq!(builder.object_count(), 3);
+        t!(builder.write(repo.path(), 0));
+        t!(repo.find_commit(commit));
+    }
+
     #[test]
     fn progress_callback() {
         let mut progress_called = false;
@@ -426,6 +475,23 @@ mod tests {
         assert_eq!(progress_called, false);
     }
 
+    #[test]
+    fn progress_callback_with_write() {
+        let mut progress_called = false;
+        {
+            let (_td, repo) = crate::test::repo_init();
+            let mut builder = t!(repo.packbuilder());
+            let (commit, _tree) = crate::test::commit(&repo);
+            t!(builder.set_progress_callback(|_, _, _| {
+                progress_called = true;
+                true
+            }));
+            t!(builder.insert_commit(commit));
+            t!(builder.write(repo.path(), 0));
+        }
+        assert_eq!(progress_called, true);
+    }
+
     #[test]
     fn set_threads() {
         let (_td, repo) = crate::test::repo_init();