but-testing apply to test new implementation more easily in the real-world.

Author: Byron

crates/but-testing/src/args.rs

@@ -36,6 +36,14 @@ pub struct Args {
 
 #[derive(Debug, clap::Subcommand)]
 pub enum Subcommands {
+    /// Make an existing branch appear in the workspace.
+    Apply {
+        /// The 0-based place in the worktree into which the branch should be inserted.
+        #[clap(long, short = 'o')]
+        order: Option<usize>,
+        /// The name of the branch to apply to the workspace, like `feature` or `origin/other`.
+        branch_name: String,
+    },
     /// Add the given Git repository as project for use with GitButler.
     AddProject {
         /// The long name of the remote reference to track, like `refs/remotes/origin/main`,

crates/but-testing/src/command/mod.rs

@@ -3,6 +3,9 @@ use but_core::UnifiedDiff;
 use but_db::poll::ItemKind;
 use but_graph::VirtualBranchesTomlMetadata;
 use but_settings::AppSettings;
+use but_workspace::branch::OnWorkspaceMergeConflict;
+use but_workspace::branch::apply::{IntegrationMode, WorkspaceReferenceNaming};
+use but_workspace::branch::checkout::UncommitedWorktreeChanges;
 use but_workspace::branch::create_reference::{Anchor, Position};
 use but_workspace::{DiffSpec, HunkHeader};
 use gitbutler_project::{Project, ProjectId};
@@ -634,6 +637,32 @@ pub fn remove_reference(
     Ok(())
 }
 
+pub fn apply(args: &super::Args, short_name: &str, order: Option<usize>) -> anyhow::Result<()> {
+    let (repo, project, graph, mut meta) =
+        repo_and_maybe_project_and_graph(args, RepositoryOpenMode::Merge)?;
+    let branch = repo.find_reference(short_name)?;
+    let ws = graph.to_workspace()?;
+    _ = but_workspace::branch::apply(
+        branch.name(),
+        &ws,
+        &repo,
+        &mut *meta,
+        but_workspace::branch::apply::Options {
+            integration_mode: IntegrationMode::AlwaysMerge,
+            on_workspace_conflict: OnWorkspaceMergeConflict::MaterializeAndReportConflictingStacks,
+            workspace_reference_naming: WorkspaceReferenceNaming::Default,
+            uncommitted_changes: UncommitedWorktreeChanges::KeepAndAbortOnConflict,
+            order,
+        },
+    )?;
+
+    if project.is_some() {
+        // write metadata if there are projects - this is a special case while we use vb.toml.
+        ManuallyDrop::into_inner(meta);
+    }
+    Ok(())
+}
+
 pub fn create_reference(
     args: &super::Args,
     short_name: &str,

crates/but-testing/src/main.rs

@@ -7,6 +7,7 @@ use command::parse_diff_spec;
 use gix::bstr::BString;
 
 mod args;
+use crate::args::Subcommands;
 use crate::command::{RepositoryOpenMode, repo_and_maybe_project};
 use args::Args;
 
@@ -31,6 +32,7 @@ async fn main() -> Result<()> {
     }
 
     match &args.cmd {
+        Subcommands::Apply { branch_name, order } => command::apply(&args, branch_name, *order),
         args::Subcommands::AddProject {
             switch_to_workspace,
             path,
@@ -39,7 +41,6 @@ async fn main() -> Result<()> {
             path.to_owned(),
             switch_to_workspace.to_owned(),
         ),
-
         args::Subcommands::RemoveReference {
             permit_empty_stacks,
             keep_metadata,

crates/gitbutler-branch-actions/src/branch_manager/branch_creation.rs

@@ -168,7 +168,7 @@ impl BranchManager<'_> {
             let applied_branch_stack_id = ws
                 .find_segment_and_stack_by_refname(branch_to_apply)
                 .with_context(||
-                    format!("Failed to apply branch and we probably have to handle more of the outcome\n{out:?}")
+                    format!("BUG: Can't find the branch to apply in workspace, but the 'apply' function should have failed instead \n{out:?}")
                 )?
                 .0
                 .id