Patch: Stop mangling file when both pre- and post-patch file has no trailing newline

.yarn/versions/e8bbcd71.yml

@@ -0,0 +1,39 @@
+releases:
+  "@yarnpkg/cli": patch
+  "@yarnpkg/fslib": patch
+  "@yarnpkg/plugin-patch": patch
+
+declined:
+  - "@yarnpkg/plugin-catalog"
+  - "@yarnpkg/plugin-compat"
+  - "@yarnpkg/plugin-constraints"
+  - "@yarnpkg/plugin-dlx"
+  - "@yarnpkg/plugin-essentials"
+  - "@yarnpkg/plugin-exec"
+  - "@yarnpkg/plugin-file"
+  - "@yarnpkg/plugin-git"
+  - "@yarnpkg/plugin-github"
+  - "@yarnpkg/plugin-init"
+  - "@yarnpkg/plugin-interactive-tools"
+  - "@yarnpkg/plugin-jsr"
+  - "@yarnpkg/plugin-link"
+  - "@yarnpkg/plugin-nm"
+  - "@yarnpkg/plugin-npm"
+  - "@yarnpkg/plugin-npm-cli"
+  - "@yarnpkg/plugin-pack"
+  - "@yarnpkg/plugin-pnp"
+  - "@yarnpkg/plugin-pnpm"
+  - "@yarnpkg/plugin-stage"
+  - "@yarnpkg/plugin-typescript"
+  - "@yarnpkg/plugin-version"
+  - "@yarnpkg/plugin-workspace-tools"
+  - vscode-zipfs
+  - "@yarnpkg/builder"
+  - "@yarnpkg/core"
+  - "@yarnpkg/doctor"
+  - "@yarnpkg/libzip"
+  - "@yarnpkg/nm"
+  - "@yarnpkg/pnp"
+  - "@yarnpkg/pnpify"
+  - "@yarnpkg/sdks"
+  - "@yarnpkg/shell"

packages/plugin-patch/sources/tools/apply.ts

@@ -132,6 +132,8 @@ export async function applyPatch({hunks, path}: FilePatch, {baseFs, dryRun = fal
 
   const fileContents = await baseFs.readFileSync(path, `utf8`);
   const fileLines = fileContents.split(/\n/);
+  if (fileLines.at(-1) !== ``)
+    fileLines.push(``);
 
   const result: Array<Array<Modification>> = [];
 

packages/plugin-patch/tests/apply.test.ts

@@ -0,0 +1,38 @@
+import type {PortablePath}                from '@yarnpkg/fslib';
+import {npath, NodeFS, ppath, CwdFS, xfs} from '@yarnpkg/fslib';
+
+import {applyPatchFile}                   from '../sources/patchUtils';
+import {parsePatchFile}                   from '../sources/tools/parse';
+
+async function dirSnapshot(p: PortablePath) {
+  const entries = await xfs.readdirPromise(p, {withFileTypes: true, recursive: true});
+  return Object.fromEntries(
+    await Promise.all(entries.map(async entry => {
+      const rel = ppath.relative(p, ppath.join(entry.parentPath, entry.name));
+      return [rel, entry.isDirectory() ? null : await xfs.readFilePromise(ppath.join(entry.parentPath, entry.name), `utf8`)];
+    })),
+  );
+}
+
+describe(`apply`,  () => {
+  const fs = new NodeFS();
+  const fixtures = ppath.join(npath.toPortablePath(__dirname), `fixtures`, `apply`);
+
+  for (const iterator of fs.readdirSync(npath.toPortablePath(fixtures))) {
+    it(`Applies patch for '${iterator}'`, async () => {
+      const fixture = ppath.join(fixtures, iterator);
+
+      const snapshot = await xfs.mktempPromise(async tmp => {
+        await xfs.copyPromise(tmp, ppath.join(fixture, `a`));
+        await applyPatchFile(
+          parsePatchFile(await fs.readFilePromise(ppath.join(fixture, `patch.patch`), `utf8`)),
+          {baseFs: new CwdFS(tmp)},
+        );
+
+        return await dirSnapshot(tmp);
+      });
+
+      expect(snapshot).toMatchObject(await dirSnapshot(ppath.join(fixture, `b`)));
+    });
+  }
+});

packages/plugin-patch/tests/diffFolders.test.ts

@@ -5,7 +5,7 @@ import {parsePatchFile} from '../sources/tools/parse';
 
 describe(`diffFolders`,  () => {
   const fs = new NodeFS();
-  const fixtures = npath.join(__dirname, `fixtures`);
+  const fixtures = npath.join(__dirname, `fixtures`, `diff`);
 
   for (const iterator of fs.readdirSync(npath.toPortablePath(fixtures))) {
     it(`Makes and parses diff for '${iterator}'`, async () => {

packages/plugin-patch/tests/fixtures/apply/no-newline/a/foo.txt

@@ -0,0 +1 @@
+foo

packages/plugin-patch/tests/fixtures/apply/no-newline/b/foo.txt

@@ -0,0 +1,2 @@
+foo
+bar

packages/plugin-patch/tests/fixtures/apply/no-newline/patch.patch

@@ -0,0 +1,8 @@
+diff --git a/foo.txt b/foo.txt
+index 19102815663d23f8b75a47e7a01965dcdc96468c..a907ec3f431eeb6b1c75799a7e4ba73ca6dc627a 100644
+--- a/foo.txt
++++ b/foo.txt
+@@ -1 +1,2 @@
+ foo
++bar
+\ No newline at end of file

packages/yarnpkg-fslib/sources/NodeFS.ts

@@ -12,6 +12,8 @@ function direntToPortable(dirent: Dirent<NativePath>): Dirent<PortablePath> {
 
   if (typeof dirent.path === `string`)
     portableDirent.path = npath.toPortablePath(dirent.path);
+  if (typeof dirent.parentPath === `string`)
+    portableDirent.parentPath = npath.toPortablePath(dirent.parentPath);
 
   return portableDirent;
 }