metro-memory-fs: add unlinkSync()

Reviewed By: rubennorte

Differential Revision: D7443805

fbshipit-source-id: 53368103f9230622250be62cde2474c21a930be8

packages/metro-memory-fs/src/__tests__/index-test.js

@@ -411,6 +411,15 @@ describe('watch', () => {
     watcher.close();
   });
 
+  it('reports unlinked files', () => {
+    const changedPaths = [];
+    fs.writeFileSync('/bar.txt', 'text');
+    const watcher = collectWatchEvents('/', {}, changedPaths);
+    fs.unlinkSync('/bar.txt');
+    expect(changedPaths).toEqual([['rename', 'bar.txt']]);
+    watcher.close();
+  });
+
   function collectWatchEvents(entPath, options, events) {
     return fs.watch(entPath, options, (eventName, filePath) => {
       events.push([eventName, filePath]);
@@ -418,6 +427,54 @@ describe('watch', () => {
   }
 });
 
+describe('unlink', () => {
+  it('removes a file', () => {
+    fs.writeFileSync('/foo.txt', 'test');
+    expect(fs.readdirSync('/')).toEqual(['foo.txt']);
+    fs.unlinkSync('/foo.txt');
+    expect(fs.readdirSync('/')).toEqual([]);
+    try {
+      fs.readFileSync('/foo.txt', 'utf8');
+      throw new Error('should not reach here');
+    } catch (error) {
+      if (error.code !== 'ENOENT') {
+        throw error;
+      }
+    }
+  });
+
+  it('removes a symlink (not the linked file)', () => {
+    fs.writeFileSync('/foo.txt', 'test');
+    fs.symlinkSync('foo.txt', '/bar.txt');
+    expect(fs.readdirSync('/')).toEqual(['foo.txt', 'bar.txt']);
+    fs.unlinkSync('/bar.txt');
+    expect(fs.readdirSync('/')).toEqual(['foo.txt']);
+  });
+
+  it('throws for non existent files', () => {
+    try {
+      fs.unlinkSync('/nonexistent.txt');
+      throw new Error('should not reach here');
+    } catch (error) {
+      if (error.code !== 'ENOENT') {
+        throw error;
+      }
+    }
+  });
+
+  it('throws for directories', () => {
+    fs.mkdirSync('/foo');
+    try {
+      fs.unlinkSync('/foo');
+      throw new Error('should not reach here');
+    } catch (error) {
+      if (error.code !== 'EISDIR') {
+        throw error;
+      }
+    }
+  });
+});
+
 it('throws when trying to read inexistent file', () => {
   expectFsError('ENOENT', () => fs.readFileSync('/foo.txt'));
 });

packages/metro-memory-fs/src/index.js

@@ -101,6 +101,7 @@ const ASYNC_FUNC_NAMES = [
   'readFile',
   'realpath',
   'stat',
+  'unlink',
   'write',
   'writeFile',
 ];
@@ -488,6 +489,23 @@ class MemoryFs {
     return rst;
   };
 
+  unlinkSync = (filePath: string | Buffer) => {
+    filePath = pathStr(filePath);
+    const {basename, dirNode, dirPath, node} = this._resolve(filePath, {
+      keepFinalSymlink: true,
+    });
+    if (node == null) {
+      throw makeError('ENOENT', filePath, 'no such file or directory');
+    }
+    if (node.type !== 'file' && node.type !== 'symbolicLink') {
+      throw makeError('EISDIR', filePath, 'cannot unlink a directory');
+    }
+    dirNode.entries.delete(basename);
+    this._emitFileChange(dirPath.concat([[basename, node]]), {
+      eventType: 'rename',
+    });
+  };
+
   createWriteStream = (
     filePath: string | Buffer,
     options?: