Fix for a race condition on Linux

index.js

@@ -136,6 +136,8 @@ const getAbsolutePath = (path, cwd) => {
 
 const undef = (opts, key) => opts[key] === undefined;
 
+const NODE_MAJOR_VERSION = Number(process.versions.node.split('.')[0]);
+
 /**
  * Directory entry.
  * @property {Path} path
@@ -950,6 +952,17 @@ _readdirp(root, opts) {
       stream = undefined;
     }
   });
+
+  if (NODE_MAJOR_VERSION < 10) {
+    // On Node 8 Readable.push() throws when the stream is destroyed
+    // even though the documentation says it should be silently ignored.
+    const superPush = stream.push.bind(stream);
+    stream.push = function (...args) {
+      if (this.destroyed) return false;
+      return superPush(...args);
+    }
+  }
+
   return stream;
 }
 

lib/nodefs-handler.js

@@ -570,6 +570,11 @@ async _handleDir(dir, stats, initialAdd, depth, target, wh, realpath) {
 
       this._handleRead(dirPath, false, wh, target, dir, depth, throttler);
     });
+
+    // schedule a rescan of the directory in case something
+    // appeared while we were setting up the watch
+    if (!(this.fsw.usePolling || target || this.fsw.closed))
+      this._handleRead(dir, false, wh, target, dir, depth, throttler);
   }
   return closer;
 }

test.js

@@ -487,6 +487,29 @@ const runTests = (baseopts) => {
       expect(spy.args[0][1]).to.be.ok; // stats
       rawSpy.should.have.been.called;
     });
+    if (!(baseopts.usePolling || baseopts.useFsEvents)) context('when a race happens', () => {
+      beforeEach(() => {
+        const stub = sinon.stub(fs, 'watch');
+        stub.callsFake((filename, ...rest) => {
+          // pretend a sneaky process creates a file just as we're about to set up the watch
+          if (filename.endsWith('subdir')) fs.writeFileSync(getFixturePath('subdir/add.txt'), dateNow());
+          return stub.wrappedMethod(filename, ...rest);
+        });
+      });
+      afterEach(() => fs.watch.restore());
+      it('should notice when a file appears in a new directory anyway', async () => {
+        const testDir = getFixturePath('subdir');
+        const testPath = getFixturePath('subdir/add.txt');
+        const spy = await aspy(watcher, EV_ADD);
+        spy.should.not.have.been.called;
+        await fs_mkdir(testDir, PERM_ARR);
+        await waitFor([spy]);
+        spy.should.have.been.calledOnce;
+        spy.should.have.been.calledWith(testPath);
+        expect(spy.args[0][1]).to.be.ok; // stats
+        rawSpy.should.have.been.called;
+      });
+    });
     it('should watch removed and re-added directories', async () => {
       const unlinkSpy = sinon.spy(function unlinkSpy(){});
       const addSpy = sinon.spy(function addSpy(){});
@@ -2192,8 +2215,6 @@ const runTests = (baseopts) => {
           await waitForWatcher(watcher);
           await delay(300);
           await write(getFixturePath('add.txt'), 'hello');
-          await delay(300);
-          await fs_unlink(getFixturePath('add.txt'));
         })();
       });
     });
@@ -2216,9 +2237,6 @@ const runTests = (baseopts) => {
           await watcher1.close();
           // Write a new file into the fixtures to test the EV_ADD event
           await write(getFixturePath('add.txt'), 'hello');
-          // Ensures EV_ADD is called. Immediately removing the file causes it to be skipped
-          await delay(200);
-          await fs_unlink(getFixturePath('add.txt'));
         })()
       })
     });