From c21ba92bfd37769ee06a2f3269694b6d8dfa14e9 Mon Sep 17 00:00:00 2001
From: Elizabeth Craig <elcraig@microsoft.com>
Date: Tue, 21 Sep 2021 15:27:27 -0700
Subject: [PATCH] Fix git root detection in worktrees (#389)

* Fix git root detection in worktrees

* Change files

* update naming
---
 change/backfill-2021-09-20-22-47-29-worktrees.json   |  8 ++++++++
 ...backfill-cache-2021-09-20-22-47-29-worktrees.json |  8 ++++++++
 packages/backfill/src/audit.ts                       | 12 ++++++------
 packages/cache/src/CacheStorage.ts                   |  9 ++++++---
 4 files changed, 28 insertions(+), 9 deletions(-)
 create mode 100644 change/backfill-2021-09-20-22-47-29-worktrees.json
 create mode 100644 change/backfill-cache-2021-09-20-22-47-29-worktrees.json

diff --git a/change/backfill-2021-09-20-22-47-29-worktrees.json b/change/backfill-2021-09-20-22-47-29-worktrees.json
new file mode 100644
index 00000000..a3eb4135
--- /dev/null
+++ b/change/backfill-2021-09-20-22-47-29-worktrees.json
@@ -0,0 +1,8 @@
+{
+  "type": "patch",
+  "comment": "Fix git root detection in worktrees",
+  "packageName": "backfill",
+  "email": "elcraig@microsoft.com",
+  "dependentChangeType": "patch",
+  "date": "2021-09-21T05:47:28.208Z"
+}
diff --git a/change/backfill-cache-2021-09-20-22-47-29-worktrees.json b/change/backfill-cache-2021-09-20-22-47-29-worktrees.json
new file mode 100644
index 00000000..f8945ed7
--- /dev/null
+++ b/change/backfill-cache-2021-09-20-22-47-29-worktrees.json
@@ -0,0 +1,8 @@
+{
+  "type": "patch",
+  "comment": "Fix git root detection in worktrees",
+  "packageName": "backfill-cache",
+  "email": "elcraig@microsoft.com",
+  "dependentChangeType": "patch",
+  "date": "2021-09-21T05:47:29.059Z"
+}
diff --git a/packages/backfill/src/audit.ts b/packages/backfill/src/audit.ts
index 7bb0038b..9654679d 100644
--- a/packages/backfill/src/audit.ts
+++ b/packages/backfill/src/audit.ts
@@ -11,14 +11,14 @@ let changedFilesInsideScope: string[] = [];
 let watcher: chokidar.FSWatcher;
 
 function getGitRepositoryRoot(packageRoot: string) {
-  const nearestGitFolder = findUp.sync(".git", {
-    cwd: packageRoot,
-    type: "directory",
-  });
+  // .git is typically a folder but will be a file in a worktree
+  const nearestGitInfo =
+    findUp.sync(".git", { cwd: packageRoot, type: "directory" }) ||
+    findUp.sync(".git", { cwd: packageRoot, type: "file" });
 
-  if (nearestGitFolder) {
+  if (nearestGitInfo) {
     // Return the parent folder of some/path/.git
-    return path.join(nearestGitFolder, "..");
+    return path.join(nearestGitInfo, "..");
   }
 
   return packageRoot;
diff --git a/packages/cache/src/CacheStorage.ts b/packages/cache/src/CacheStorage.ts
index b718f485..1707913c 100644
--- a/packages/cache/src/CacheStorage.ts
+++ b/packages/cache/src/CacheStorage.ts
@@ -8,14 +8,17 @@ import { Logger } from "backfill-logger";
 const savedHashOfRepos: { [gitRoot: string]: { [file: string]: string } } = {};
 
 function getRepoRoot(cwd: string): string {
-  const gitFolder = findUp.sync(".git", { cwd, type: "directory" });
-  if (!gitFolder) {
+  // .git is typically a folder but will be a file in a worktree
+  const nearestGitInfo =
+    findUp.sync(".git", { cwd, type: "directory" }) ||
+    findUp.sync(".git", { cwd, type: "file" });
+  if (!nearestGitInfo) {
     throw new Error(
       "The location that backfill is being run against is not in a git repo"
     );
   }
 
-  return dirname(gitFolder);
+  return dirname(nearestGitInfo);
 }
 
 function fetchHashesFor(cwd: string) {