fix: 'fromJSON()' did not consider cwd when creating directories

src/__tests__/volume.test.ts

@@ -197,16 +197,18 @@ describe('volume', () => {
         expect(vol.toJSON()).toEqual(json);
       });
 
-      it('Files at root with relative paths', () => {
+      it('Files and directories at root with relative paths', () => {
         const vol = new Volume();
         const json = {
           hello: 'world',
           'app.js': 'console.log(123)',
+          dir: {},
         };
         vol.fromJSON(json, '/');
         expect(vol.toJSON()).toEqual({
           '/hello': 'world',
           '/app.js': 'console.log(123)',
+          '/dir': null,
         });
       });
 

src/volume.ts

@@ -872,8 +872,9 @@ export class Volume {
     for (let filename in json) {
       const data = json[filename];
 
+      filename = resolve(filename, cwd);
+
       if (typeof data === 'string') {
-        filename = resolve(filename, cwd);
         const steps = filenameToSteps(filename);
         if (steps.length > 1) {
           const dirname = sep + steps.slice(0, steps.length - 1).join(sep);