Automatically setup the remote tracking of branches on apply

Author: Byron

crates/but-workspace/src/branch/apply.rs

@@ -139,16 +139,8 @@ pub(crate) mod function {
             order,
         }: Options,
     ) -> anyhow::Result<Outcome<'graph>> {
-        let branch_ref = repo.try_find_reference(branch)?;
-        if branch_ref
-            .as_ref()
-            .is_some_and(|r| matches!(r.target(), gix::refs::TargetRef::Symbolic(_)))
-        {
-            bail!(
-                "Refusing to apply symbolic ref '{}' due to potential ambiguity",
-                branch.shorten()
-            );
-        }
+        let branch_orig = branch;
+        let mut branch_ref = try_find_validated_ref(repo, branch)?;
         if workspace.is_branch_the_target_or_its_local_tracking_branch(branch) {
             bail!("Cannot add the target '{branch}' branch to its own workspace");
         }
@@ -169,6 +161,7 @@ pub(crate) mod function {
             branch_storage = upstream_branch_name;
             // Pretend the upstream branch is also the local tracking name.
             branch = branch_storage.as_ref();
+            branch_ref = try_find_validated_ref(repo, branch)?;
         }
         let conflicting_stack_ids = Vec::new();
         if workspace.is_reachable_from_entrypoint(branch) {
@@ -370,6 +363,9 @@ pub(crate) mod function {
         }
         // We will want to merge, but be sure the branch exists, can't apply non-existing.
         if branch_ref.is_none() {
+            if !std::ptr::eq(branch_orig, branch) {
+                todo!("Create local tracking branch");
+            }
             bail!(
                 "Cannot apply non-existing branch '{branch}'",
                 branch = branch.shorten()
@@ -720,4 +716,21 @@ pub(crate) mod function {
             ))
         }
     }
+
+    fn try_find_validated_ref<'repo>(
+        repo: &'repo gix::Repository,
+        branch: &gix::refs::FullNameRef,
+    ) -> anyhow::Result<Option<gix::Reference<'repo>>> {
+        let branch_ref = repo.try_find_reference(branch)?;
+        if branch_ref
+            .as_ref()
+            .is_some_and(|r| matches!(r.target(), gix::refs::TargetRef::Symbolic(_)))
+        {
+            bail!(
+                "Refusing to apply symbolic ref '{}' due to potential ambiguity",
+                branch.shorten()
+            );
+        }
+        Ok(branch_ref)
+    }
 }

crates/but-workspace/tests/fixtures/scenario/main-with-advanced-remote.sh

@@ -9,3 +9,8 @@ commit M1
 commit only-on-remote
 setup_target_to_match_main
 git reset --hard @~1
+
+git checkout -b soon-tracking-of-feature
+  commit without-local-tracking
+git checkout main
+turn_into_remote_branch soon-tracking-of-feature feature

crates/but-workspace/tests/workspace/branch/apply_unapply_commit_uncommit.rs

@@ -105,15 +105,17 @@ fn ws_ref_no_ws_commit_two_virtual_stacks_on_same_commit_apply_dependent_first()
 }
 
 #[test]
-fn main_with_advanced_remote() -> anyhow::Result<()> {
+fn main_with_advanced_remote_tracking_branch() -> anyhow::Result<()> {
     let (_tmp, graph, repo, _vb_version_cannot_have_remotes, _description) =
         named_writable_scenario_with_description_and_graph(
             "main-with-advanced-remote",
             |_meta| {},
         )?;
 
     insta::assert_snapshot!(visualize_commit_graph_all(&repo)?, @r"
-    * 552e7dc (origin/main) only-on-remote
+    * 6b40b15 (origin/feature) without-local-tracking
+    | * 552e7dc (origin/main) only-on-remote
+    |/  
     * 3183e43 (HEAD -> main) M1
     ");
 
@@ -146,7 +148,24 @@ fn main_with_advanced_remote() -> anyhow::Result<()> {
     }
     ");
 
-    // TODO: show how a proper local tracking branch is created on the fly.
+    // Set up an automatic tracking of origin/feature, as remote tracking branches can't be in the workspace.
+    let out = but_workspace::branch::apply(
+        r("refs/remotes/origin/feature"),
+        &ws,
+        &repo,
+        &mut meta,
+        default_options(),
+    )?;
+    insta::assert_debug_snapshot!(out, @r"
+    Outcome {
+        workspace_changed: true,
+        workspace_ref_created: true,
+    }
+    ");
+    let graph = out.graph;
+    let ws = graph.to_workspace()?;
+    // both branches, main and feature, are available in the newly created workspace ref.
+    insta::assert_snapshot!(graph_workspace(&ws), @r"");
     Ok(())
 }