test: improve commit and submodule testing

Two of the tests in radicle-git-ext and radicle-surf relied on using
the Git repository itself. This can end up being an issue when
sandboxing is involved.

This improves the situation by being able to generate commit data to
add to a temporary repository.

It also adds a helper for creating a local, temporary submodule for
testing the submodule interactions in the radicle-surf API.

Signed-off-by: Fintan Halpenny <fintan.halpenny@gmail.com>
X-Clacks-Overhead: GNU Terry Pratchett

radicle-git-ext/src/commit.rs

@@ -26,47 +26,9 @@ use trailers::{OwnedTrailer, Trailer, Trailers};
 
 use crate::author::Author;
 
-/// A git commit in its object description form, i.e. the output of
-/// `git cat-file` for a commit object.
-#[derive(Debug)]
-pub struct Commit {
-    tree: Oid,
-    parents: Vec<Oid>,
-    author: Author,
-    committer: Author,
-    headers: Headers,
-    message: String,
-    trailers: Vec<OwnedTrailer>,
-}
+pub type Commit = CommitData<Oid, Oid>;
 
 impl Commit {
-    pub fn new<P, I, T>(
-        tree: Oid,
-        parents: P,
-        author: Author,
-        committer: Author,
-        headers: Headers,
-        message: String,
-        trailers: I,
-    ) -> Self
-    where
-        P: IntoIterator<Item = Oid>,
-        I: IntoIterator<Item = T>,
-        OwnedTrailer: From<T>,
-    {
-        let trailers = trailers.into_iter().map(OwnedTrailer::from).collect();
-        let parents = parents.into_iter().collect();
-        Self {
-            tree,
-            parents,
-            author,
-            committer,
-            headers,
-            message,
-            trailers,
-        }
-    }
-
     /// Read the [`Commit`] from the `repo` that is expected to be found at
     /// `oid`.
     pub fn read(repo: &git2::Repository, oid: Oid) -> Result<Self, error::Read> {
@@ -83,14 +45,68 @@ impl Commit {
         Ok(odb.write(ObjectType::Commit, self.to_string().as_bytes())?)
     }
 
-    /// The tree [`Oid`] this commit points to.
-    pub fn tree(&self) -> Oid {
-        self.tree
+    fn verify_for_write(&self, odb: &git2::Odb) -> Result<(), error::Write> {
+        for parent in &self.parents {
+            verify_object(odb, parent, ObjectType::Commit)?;
+        }
+        verify_object(odb, &self.tree, ObjectType::Tree)?;
+
+        Ok(())
+    }
+}
+
+/// A git commit in its object description form, i.e. the output of
+/// `git cat-file` for a commit object.
+#[derive(Debug)]
+pub struct CommitData<Tree, Parent> {
+    tree: Tree,
+    parents: Vec<Parent>,
+    author: Author,
+    committer: Author,
+    headers: Headers,
+    message: String,
+    trailers: Vec<OwnedTrailer>,
+}
+
+impl<Tree, Parent> CommitData<Tree, Parent> {
+    pub fn new<P, I, T>(
+        tree: Tree,
+        parents: P,
+        author: Author,
+        committer: Author,
+        headers: Headers,
+        message: String,
+        trailers: I,
+    ) -> Self
+    where
+        P: IntoIterator<Item = Parent>,
+        I: IntoIterator<Item = T>,
+        OwnedTrailer: From<T>,
+    {
+        let trailers = trailers.into_iter().map(OwnedTrailer::from).collect();
+        let parents = parents.into_iter().collect();
+        Self {
+            tree,
+            parents,
+            author,
+            committer,
+            headers,
+            message,
+            trailers,
+        }
     }
 
-    /// The parent [`Oid`]s of this commit.
-    pub fn parents(&self) -> impl Iterator<Item = Oid> + '_ {
-        self.parents.iter().copied()
+    /// The tree this commit points to.
+    pub fn tree(&self) -> &Tree {
+        &self.tree
+    }
+
+    /// The parents of this commit.
+    pub fn parents(&self) -> impl Iterator<Item = Parent> + '_
+    where
+        Parent: Clone,
+    {
+        self.parents.iter().cloned()
     }
 
     /// The author of this commit, i.e. the header corresponding to `author`.
@@ -136,13 +152,49 @@ impl Commit {
         self.trailers.iter()
     }
 
-    fn verify_for_write(&self, odb: &git2::Odb) -> Result<(), error::Write> {
-        for parent in &self.parents {
-            verify_object(odb, parent, ObjectType::Commit)?;
-        }
-        verify_object(odb, &self.tree, ObjectType::Tree)?;
+    /// Convert the `CommitData::tree` into a value of type `U`. The
+    /// conversion function `f` can be fallible.
+    ///
+    /// For example, `map_tree` can be used to turn raw tree data into
+    /// an `Oid` by writing it to a repository.
+    pub fn map_tree<U, E, F>(self, f: F) -> Result<CommitData<U, Parent>, E>
+    where
+        F: FnOnce(Tree) -> Result<U, E>,
+    {
+        Ok(CommitData {
+            tree: f(self.tree)?,
+            parents: self.parents,
+            author: self.author,
+            committer: self.committer,
+            headers: self.headers,
+            message: self.message,
+            trailers: self.trailers,
+        })
+    }
 
-        Ok(())
+    /// Convert the `CommitData::parents` into a vector containing
+    /// values of type `U`. The conversion function `f` can be
+    /// fallible.
+    ///
+    /// For example, `map_parents` can be used to resolve the `Oid`s
+    /// to their respective `git2::Commit`s.
+    pub fn map_parents<U, E, F>(self, f: F) -> Result<CommitData<Tree, U>, E>
+    where
+        F: FnMut(Parent) -> Result<U, E>,
+    {
+        Ok(CommitData {
+            tree: self.tree,
+            parents: self
+                .parents
+                .into_iter()
+                .map(f)
+                .collect::<Result<Vec<_>, _>>()?,
+            author: self.author,
+            committer: self.committer,
+            headers: self.headers,
+            message: self.message,
+            trailers: self.trailers,
+        })
     }
 }
 

radicle-git-ext/src/commit/headers.rs

@@ -10,6 +10,7 @@ const BEGIN_PGP: &str = "-----BEGIN PGP SIGNATURE-----\n";
 pub struct Headers(pub(super) Vec<(String, String)>);
 
 /// A `gpgsig` signature stored in a [`crate::commit::Commit`].
+#[derive(Debug)]
 pub enum Signature<'a> {
     /// A PGP signature, i.e. starts with `-----BEGIN PGP SIGNATURE-----`.
     Pgp(Cow<'a, str>),