fix(merge): auto-resolve tree deletion conflict

Author: alex-titarenko

src/utils/mergeTree.ts

@@ -139,6 +139,7 @@ export async function mergeTree({
             (base && (await base.type()) !== 'blob') ||
             (theirs && (await theirs.type()) !== 'blob')
           ) {
+            // Created tree (folder) with the same path
             if (
               (ours && (await ours.type()) === 'tree') &&
               !base &&
@@ -151,6 +152,11 @@ export async function mergeTree({
                 }
             }
 
+            // Deleted tree (folder) with the same path
+            if (!ours && !theirs && (base && (await base.type() === 'tree'))) {
+              return undefined
+            }
+
             throw new MergeConflictError(filepath)
           }
 
@@ -199,7 +205,7 @@ export async function mergeTree({
       return parent
     },
   })
-  return results.oid
+  return results?.oid
 }
 
 async function modified(entry: WalkerEntry, base: WalkerEntry) {

tests/merge.test.ts

@@ -9,6 +9,7 @@ import {
   init,
   log,
   merge,
+  remove,
   resolveRef
 } from 'git-essentials'
 import { FsFixtureData, makeFsFixture } from './helpers/makeFsFixture'
@@ -519,6 +520,87 @@ describe('merge-e2e', () => {
     expect(newSubDirFiles.length).toBe(2)
   })
 
+  it('merge two branches that deleted same folder', async () => {
+    // ARRANGE
+    const { fs, dir } = await makeFsFixture()
+
+    // initializing new repo
+    await init({ fs, dir, defaultBranch: branch1Name })
+    await fs.mkdir(path.resolve(dir, newDirName))
+    await fs.writeFile(path.resolve(dir, newDirName, '.gitkeep'), '')
+    await add({ fs, dir, filepath: path.resolve(newDirName, '.gitkeep') })
+    await commit({ fs, dir, message: 'first commit', author: { name: 'author0' } })
+    await branch({ fs, dir, ref: branch2Name, checkout: false })
+
+    // deleting files to the branch1
+    await fs.rm(path.resolve(dir, newDirName), { recursive: true })
+    await remove({ fs, dir, filepath: path.resolve(newDirName, '.gitkeep') })
+    await commit({ fs, dir, message: 'add files', author: { name: 'author1' } })
+
+    // deleting files to the branch2
+    await checkout({ fs, dir, ref: branch2Name })
+    await fs.rm(path.resolve(dir, newDirName), { recursive: true })
+    await remove({ fs, dir, filepath: path.resolve(newDirName, '.gitkeep') })
+    await commit({ fs, dir, message: 'add files', author: { name: 'author2' } })
+
+    // switching back to the branch1
+    await checkout({ fs, dir, ref: branch1Name })
+
+    // ACT
+    const m = await merge({ fs, dir, ours: branch1Name, theirs: branch2Name, author: { name: 'author3' } })
+    await checkout({ fs, dir, ref: branch1Name })
+
+    // ASSERT
+    expect(m.alreadyMerged).toBeFalsy()
+    expect(m.mergeCommit).toBeTruthy()
+    const rootDirFiles = await fs.readdir(dir)
+    expect(rootDirFiles.length).toBe(1)
+  })
+
+  it('merge two branches that deleted folder and it\'s subfolder', async () => {
+    // ARRANGE
+    const { fs, dir } = await makeFsFixture()
+
+    // initializing new repo
+    await init({ fs, dir, defaultBranch: branch1Name })
+    await fs.mkdir(path.resolve(dir, newDirName))
+
+    await fs.writeFile(path.resolve(dir, newDirName, '.gitkeep'), '')
+    await add({ fs, dir, filepath: path.resolve(newDirName, '.gitkeep') })
+
+    await fs.mkdir(path.resolve(dir, newDirName, 'sub-folder'))
+    await fs.writeFile(path.resolve(dir, newDirName, 'sub-folder', 'nested-file.txt'), 'some content')
+    await add({ fs, dir, filepath: path.resolve(newDirName, 'sub-folder', 'nested-file.txt') })
+
+    await commit({ fs, dir, message: 'first commit', author: { name: 'author0' } })
+    await branch({ fs, dir, ref: branch2Name, checkout: false })
+
+    // deleting files to the branch1
+    await fs.rm(path.resolve(dir, newDirName), { recursive: true })
+    await remove({ fs, dir, filepath: path.resolve(newDirName, '.gitkeep') })
+    await remove({ fs, dir, filepath: path.resolve(newDirName, 'sub-folder', 'nested-file.txt') })
+    await commit({ fs, dir, message: 'add files', author: { name: 'author1' } })
+
+    // deleting files to the branch2
+    await checkout({ fs, dir, ref: branch2Name })
+    await fs.rm(path.resolve(dir, newDirName, 'sub-folder'), { recursive: true })
+    await remove({ fs, dir, filepath: path.resolve(newDirName, 'sub-folder', 'nested-file.txt') })
+    await commit({ fs, dir, message: 'add files', author: { name: 'author2' } })
+
+    // switching back to the branch1
+    await checkout({ fs, dir, ref: branch1Name })
+
+    // ACT
+    const m = await merge({ fs, dir, ours: branch1Name, theirs: branch2Name, author: { name: 'author3' } })
+    await checkout({ fs, dir, ref: branch1Name })
+
+    // ASSERT
+    expect(m.alreadyMerged).toBeFalsy()
+    expect(m.mergeCommit).toBeTruthy()
+    const rootDirFiles = await fs.readdir(dir)
+    expect(rootDirFiles.length).toBe(1)
+  })
+
   it('merge new folder and file with the same name should fail', async () => {
     // ARRANGE
     const { fs, dir } = await makeFsFixture()