From b01659d2ea8d6a2085f3ea8f226f4c76138290ef Mon Sep 17 00:00:00 2001
From: Piotr Bosak <piotr.bosak@summer.agency>
Date: Fri, 24 Jun 2022 10:41:38 +0200
Subject: [PATCH 1/3] fix: correctly handle git stash when using MSYS2

---
 lib/gitWorkflow.js | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/lib/gitWorkflow.js b/lib/gitWorkflow.js
index 9813aa4dd..45167cf5e 100644
--- a/lib/gitWorkflow.js
+++ b/lib/gitWorkflow.js
@@ -103,6 +103,16 @@ export class GitWorkflow {
       ctx.errors.add(GetBackupStashError)
       throw new Error('lint-staged automatic backup is missing!')
     }
+
+    /**
+     * https://github.com/okonet/lint-staged/issues/1121
+     * Detect MSYS in login shell mode and escape braces
+     * to prevent interpolation
+     */
+    if (!!process.env.MSYSTEM && !!process.env.LOGINSHELL) {
+      return `refs/stash@\\{${index}\\}`
+    }
+
     return `refs/stash@{${index}}`
   }
 

From e3c39dbd57e4c8dbeb98bf15834feeb4f5224a18 Mon Sep 17 00:00:00 2001
From: Piotr Bosak <piotr.bosak@summer.agency>
Date: Fri, 24 Jun 2022 15:11:57 +0200
Subject: [PATCH 2/3] test: Adds unit tests for MSYS shell detection (as
 recommended by @iiroj)

---
 lib/gitWorkflow.js               |  2 +-
 test/unit/getBackupStash.spec.js | 94 ++++++++++++++++++++++++++++++++
 2 files changed, 95 insertions(+), 1 deletion(-)
 create mode 100644 test/unit/getBackupStash.spec.js

diff --git a/lib/gitWorkflow.js b/lib/gitWorkflow.js
index 45167cf5e..9f0df245d 100644
--- a/lib/gitWorkflow.js
+++ b/lib/gitWorkflow.js
@@ -43,7 +43,7 @@ const processRenames = (files, includeRenameFrom = true) =>
     return flattened
   }, [])
 
-const STASH = 'lint-staged automatic backup'
+export const STASH = 'lint-staged automatic backup'
 
 const PATCH_UNSTAGED = 'lint-staged_unstaged.patch'
 
diff --git a/test/unit/getBackupStash.spec.js b/test/unit/getBackupStash.spec.js
new file mode 100644
index 000000000..9291ff2bb
--- /dev/null
+++ b/test/unit/getBackupStash.spec.js
@@ -0,0 +1,94 @@
+import { execGit } from '../../lib/execGit.js'
+import { GitWorkflow, STASH } from '../../lib/gitWorkflow.js'
+import { getInitialState } from '../../lib/state.js'
+import { GetBackupStashError } from '../../lib/symbols'
+
+jest.mock('../../lib/execGit.js', () => ({
+  execGit: jest.fn(async () => ''),
+}))
+
+describe('gitWorkflow', () => {
+  const options = { gitConfigDir: '.' }
+
+  describe('getBackupStash', () => {
+    it('should throw when stash not found', async () => {
+      const gitWorkflow = new GitWorkflow(options)
+      const ctx = getInitialState()
+
+      await expect(gitWorkflow.getBackupStash(ctx)).rejects.toThrowError(
+        'lint-staged automatic backup is missing!'
+      )
+
+      expect(ctx.errors.has(GetBackupStashError)).toEqual(true)
+    })
+
+    it('should throw when stash not found even when other stashes are', async () => {
+      const gitWorkflow = new GitWorkflow(options)
+      const ctx = getInitialState()
+
+      execGit.mockResolvedValueOnce('stash@{0}: some random stuff')
+
+      await expect(gitWorkflow.getBackupStash(ctx)).rejects.toThrowError(
+        'lint-staged automatic backup is missing!'
+      )
+
+      expect(ctx.errors.has(GetBackupStashError)).toEqual(true)
+    })
+
+    it('should return ref to the backup stash', async () => {
+      const gitWorkflow = new GitWorkflow(options)
+      const ctx = getInitialState()
+
+      execGit.mockResolvedValueOnce(
+        [
+          'stash@{0}: some random stuff',
+          `stash@{1}: ${STASH}`,
+          'stash@{2}: other random stuff',
+        ].join('\n')
+      )
+
+      await expect(gitWorkflow.getBackupStash(ctx)).resolves.toEqual('refs/stash@{1}')
+    })
+
+    it('should return unescaped ref to the backup stash when using MSYS2 without login shell', async () => {
+      const gitWorkflow = new GitWorkflow(options)
+      const ctx = getInitialState()
+
+      process.env.MSYSTEM = 'MSYS'
+      delete process.env.LOGINSHELL
+
+      execGit.mockResolvedValueOnce(
+        [
+          'stash@{0}: some random stuff',
+          `stash@{1}: ${STASH}`,
+          'stash@{2}: other random stuff',
+        ].join('\n')
+      )
+
+      await expect(gitWorkflow.getBackupStash(ctx)).resolves.toEqual('refs/stash@{1}')
+
+      delete process.env.MSYSTEM
+    })
+
+    it('should return escaped ref to the backup stash when using MSYS2 with login shell', async () => {
+      const gitWorkflow = new GitWorkflow(options)
+      const ctx = getInitialState()
+
+      process.env.MSYSTEM = 'MSYS'
+      process.env.LOGINSHELL = 'bash'
+
+      execGit.mockResolvedValueOnce(
+        [
+          'stash@{0}: some random stuff',
+          `stash@{1}: ${STASH}`,
+          'stash@{2}: other random stuff',
+        ].join('\n')
+      )
+
+      await expect(gitWorkflow.getBackupStash(ctx)).resolves.toEqual('refs/stash@\\{1\\}')
+
+      delete process.env.MSYSTEM
+      delete process.env.LOGINSHELL
+    })
+  })
+})

From 0d7d7a6c0f5661dc4e502d1d347e66d60c5a7407 Mon Sep 17 00:00:00 2001
From: Piotr Bosak <piotr.bosak@summer.agency>
Date: Fri, 24 Jun 2022 15:17:45 +0200
Subject: [PATCH 3/3] improvement: LOGINSHELL env variable deletion is
 unnecessary if tests aren't run on MSYS2 environment

---
 test/unit/getBackupStash.spec.js | 1 -
 1 file changed, 1 deletion(-)

diff --git a/test/unit/getBackupStash.spec.js b/test/unit/getBackupStash.spec.js
index 9291ff2bb..4c55fab38 100644
--- a/test/unit/getBackupStash.spec.js
+++ b/test/unit/getBackupStash.spec.js
@@ -55,7 +55,6 @@ describe('gitWorkflow', () => {
       const ctx = getInitialState()
 
       process.env.MSYSTEM = 'MSYS'
-      delete process.env.LOGINSHELL
 
       execGit.mockResolvedValueOnce(
         [