path-watcher-spec.js

/** @babel */

import temp from 'temp';
import fs from 'fs-plus';
import path from 'path';
import { promisify } from 'util';

import { CompositeDisposable } from 'event-kit';
import { watchPath, stopAllWatchers } from '../src/path-watcher';

temp.track();

const writeFile = promisify(fs.writeFile);
const mkdir = promisify(fs.mkdir);
const appendFile = promisify(fs.appendFile);
const realpath = promisify(fs.realpath);

const tempMkdir = promisify(temp.mkdir);

describe('watchPath', function() {
  let subs;

  beforeEach(function() {
    subs = new CompositeDisposable();
  });

  afterEach(async function() {
    subs.dispose();
    await stopAllWatchers();
  });

  function waitForChanges(watcher, ...fileNames) {
    const waiting = new Set(fileNames);
    let fired = false;
    const relevantEvents = [];

    return new Promise(resolve => {
      const sub = watcher.onDidChange(events => {
        for (const event of events) {
          if (waiting.delete(event.path)) {
            relevantEvents.push(event);
          }
        }

        if (!fired && waiting.size === 0) {
          fired = true;
          resolve(relevantEvents);
          sub.dispose();
        }
      });
    });
  }

  describe('watchPath()', function() {
    it('resolves the returned promise when the watcher begins listening', async function() {
      const rootDir = await tempMkdir('atom-fsmanager-test-');

      const watcher = await watchPath(rootDir, {}, () => {});
      expect(watcher.constructor.name).toBe('PathWatcher');
    });

    it('reuses an existing native watcher and resolves getStartPromise immediately if attached to a running watcher', async function() {
      const rootDir = await tempMkdir('atom-fsmanager-test-');

      const watcher0 = await watchPath(rootDir, {}, () => {});
      const watcher1 = await watchPath(rootDir, {}, () => {});

      expect(watcher0.native).toBe(watcher1.native);
    });

    it("reuses existing native watchers even while they're still starting", async function() {
      const rootDir = await tempMkdir('atom-fsmanager-test-');

      const [watcher0, watcher1] = await Promise.all([
        watchPath(rootDir, {}, () => {}),
        watchPath(rootDir, {}, () => {})
      ]);
      expect(watcher0.native).toBe(watcher1.native);
    });

    it("doesn't attach new watchers to a native watcher that's stopping", async function() {
      const rootDir = await tempMkdir('atom-fsmanager-test-');

      const watcher0 = await watchPath(rootDir, {}, () => {});
      const native0 = watcher0.native;

      watcher0.dispose();
      const watcher1 = await watchPath(rootDir, {}, () => {});

      expect(watcher1.native).not.toBe(native0);
    });

    for (let i = 0; i < 10000; i++) {
      fit(`reuses an existing native watcher on a parent directory and filters events (#${i})`, async function() {
        const rootDir = await tempMkdir('atom-fsmanager-test-').then(realpath);
        const rootFile = path.join(rootDir, 'rootfile.txt');
        const subDir = path.join(rootDir, 'subdir');
        const subFile = path.join(subDir, 'subfile.txt');

        await mkdir(subDir);

        // Keep the watchers alive with an undisposed subscription
        const rootWatcher = await watchPath(rootDir, {}, () => {});
        const childWatcher = await watchPath(subDir, {}, () => {});

        expect(rootWatcher.native).toBe(childWatcher.native);
        expect(rootWatcher.native.isRunning()).toBe(true);

        const firstChanges = Promise.all([
          waitForChanges(rootWatcher, subFile),
          waitForChanges(childWatcher, subFile)
        ]);
        await writeFile(subFile, 'subfile\n', { encoding: 'utf8' });
        await firstChanges;

        const nextRootEvent = waitForChanges(rootWatcher, rootFile);
        await writeFile(rootFile, 'rootfile\n', { encoding: 'utf8' });
        await nextRootEvent;
      });
    }

    for (let i = 0; i < 10000; i++) {
      fit(`adopts existing child watchers and filters events appropriately to them (#${i})`, async function() {
        const parentDir = await tempMkdir('atom-fsmanager-test-').then(
          realpath
        );

        // Create the directory tree
        const rootFile = path.join(parentDir, 'rootfile.txt');
        const subDir0 = path.join(parentDir, 'subdir0');
        const subFile0 = path.join(subDir0, 'subfile0.txt');
        const subDir1 = path.join(parentDir, 'subdir1');
        const subFile1 = path.join(subDir1, 'subfile1.txt');

        await mkdir(subDir0);
        await mkdir(subDir1);
        await Promise.all([
          writeFile(rootFile, 'rootfile\n', { encoding: 'utf8' }),
          writeFile(subFile0, 'subfile 0\n', { encoding: 'utf8' }),
          writeFile(subFile1, 'subfile 1\n', { encoding: 'utf8' })
        ]);

        // Begin the child watchers and keep them alive
        const subWatcher0 = await watchPath(subDir0, {}, () => {});
        const subWatcherChanges0 = waitForChanges(subWatcher0, subFile0);

        const subWatcher1 = await watchPath(subDir1, {}, () => {});
        const subWatcherChanges1 = waitForChanges(subWatcher1, subFile1);

        expect(subWatcher0.native).not.toBe(subWatcher1.native);

        // Create the parent watcher
        const parentWatcher = await watchPath(parentDir, {}, () => {});
        const parentWatcherChanges = waitForChanges(
          parentWatcher,
          rootFile,
          subFile0,
          subFile1
        );

        expect(subWatcher0.native).toBe(parentWatcher.native);
        expect(subWatcher1.native).toBe(parentWatcher.native);

        // Ensure events are filtered correctly
        await Promise.all([
          appendFile(rootFile, 'change\n', { encoding: 'utf8' }),
          appendFile(subFile0, 'change\n', { encoding: 'utf8' }),
          appendFile(subFile1, 'change\n', { encoding: 'utf8' })
        ]);

        await Promise.all([
          subWatcherChanges0,
          subWatcherChanges1,
          parentWatcherChanges
        ]);
      });
    }
  });
});