debounce file change callback to avoid occasional double trigger

Author: ldgit

package-lock.json

@@ -38,7 +38,8 @@
     "chokidar": "^2.0.4",
     "commander": "^2.19.0",
     "date-fns": "^1.30.1",
-    "glob": "^7.1.3"
+    "glob": "^7.1.3",
+    "lodash": "^4.17.11"
   },
   "optionalDependencies": {
     "fsevents": "^1.0.0"

package.json

@@ -1,13 +1,14 @@
-const fileWatcher = require('chokidar');
 const fs = require('fs');
+const fileWatcher = require('chokidar');
+const _ = require('lodash');
 const { consolePrinter } = require('./printer');
 
 module.exports = {
-  createWatcher: configureCreateWatcher.bind(null, consolePrinter),
+  createWatcher: configureCreateWatcher.bind(null, consolePrinter, _.debounce),
   configureCreateWatcher,
 };
 
-function configureCreateWatcher(printer, configuration) {
+function configureCreateWatcher(printer, debounce, configuration) {
   const { environments } = configuration;
   let watcher;
 
@@ -22,7 +23,9 @@ function configureCreateWatcher(printer, configuration) {
         atomic: true,
         depth: 0,
       });
-      watcher.on('change', callback);
+
+      // We debounce the change callback to avoid occasional double trigger
+      watcher.on('change', debounce(callback, 100));
       watcher.on('ready', () => {
         printer.info(`Watching ${getFilesWatchedCount(environments, watcher.getWatched())} file(s)`);
       });

src/file-watcher.js

@@ -21,7 +21,7 @@ describe('watcher', function watcherTest() {
     };
     process.chdir(path.join('.', 'test'));
     printerSpy = createPrinterSpy();
-    watcher = configureCreateWatcher(printerSpy, configuration);
+    watcher = configureCreateWatcher(printerSpy, debounceDummy, configuration);
   });
 
   afterEach(() => {
@@ -136,3 +136,7 @@ describe('watcher', function watcherTest() {
     };
   }
 });
+
+function debounceDummy(func) {
+  return func;
+}

test/file-watcher.test.js

@@ -6,6 +6,9 @@ const { runCommands } = require('../../src/command-runner');
 const createRunCommandsSpy = require('../helpers/run-commands-spy');
 const { StdinMock } = require('./../helpers/mockStdio');
 
+const wait = miliseconds => new Promise(resolve => setTimeout(resolve, miliseconds));
+const waitForDebounce = () => wait(110);
+
 describe('argus', function argusTestSuite() {
   this.slow(500);
 
@@ -42,9 +45,11 @@ describe('argus', function argusTestSuite() {
       fork(pathToTouchScript, [path.join('.', 'src', 'PhpClass.php')]);
 
       watcher.on('change', () => {
-        assert.equal(runCommandsSpy.getLastRunCommands()[0].command, 'echo');
-        assert.deepEqual(runCommandsSpy.getLastRunCommands()[0].args, ['tests/src/PhpClassTest.php']);
-        done();
+        waitForDebounce().then(() => {
+          assert.equal(runCommandsSpy.getLastRunCommands()[0].command, 'echo');
+          assert.deepEqual(runCommandsSpy.getLastRunCommands()[0].args, ['tests/src/PhpClassTest.php']);
+          done();
+        });
       });
     });
 
@@ -53,9 +58,11 @@ describe('argus', function argusTestSuite() {
       fork(pathToTouchScript, [path.join('.', 'tests', 'src', 'PhpClassTest.php')]);
 
       watcher.on('change', () => {
-        assert.equal(runCommandsSpy.getLastRunCommands()[0].command, 'echo');
-        assert.deepEqual(runCommandsSpy.getLastRunCommands()[0].args, ['tests/src/PhpClassTest.php']);
-        done();
+        waitForDebounce().then(() => {
+          assert.equal(runCommandsSpy.getLastRunCommands()[0].command, 'echo');
+          assert.deepEqual(runCommandsSpy.getLastRunCommands()[0].args, ['tests/src/PhpClassTest.php']);
+          done();
+        });
       });
     });
 
@@ -65,12 +72,14 @@ describe('argus', function argusTestSuite() {
 
       return new Promise((resolve) => {
         watcher.on('change', () => {
-          assert.strictEqual(runCommandsSpy.getCommandsBatchRunCount(), 1);
-          assert.equal(runCommandsSpy.getLastRunCommands()[0].command, 'echo');
-          assert.deepEqual(runCommandsSpy.getLastRunCommands()[0].args, ['tests/src/PhpClassTest.php']);
-
-          mockStdin.on('data', resolve);
-          mockStdin.push('r');
+          waitForDebounce().then(() => {
+            assert.strictEqual(runCommandsSpy.getCommandsBatchRunCount(), 1);
+            assert.equal(runCommandsSpy.getLastRunCommands()[0].command, 'echo');
+            assert.deepEqual(runCommandsSpy.getLastRunCommands()[0].args, ['tests/src/PhpClassTest.php']);
+
+            mockStdin.on('data', resolve);
+            mockStdin.push('r');
+          });
         });
       }).then(() => {
         assert.strictEqual(runCommandsSpy.getCommandsBatchRunCount(), 2);
@@ -104,15 +113,17 @@ describe('argus', function argusTestSuite() {
       fork(pathToTouchScript, [path.join('.', 'src', 'Class.php')]);
 
       watcher.on('change', () => {
-        assert.equal(runCommandsSpy.getLastRunCommands().length, 2, 'Expected only two commands to run');
-        assert.equal(runCommandsSpy.getLastRunCommands()[0].command, 'vendor/bin/phpunit');
-        assert.deepEqual(runCommandsSpy.getLastRunCommands()[0].args, ['tests/unit/src/ClassTest.php']);
-        assert.equal(runCommandsSpy.getLastRunCommands()[1].command, 'vendor/bin/phpunit');
-        assert.deepEqual(
-          runCommandsSpy.getLastRunCommands()[1].args,
-          ['-c', 'phpunit-integration.xml', 'tests/integration/src/ClassTest.php'],
-        );
-        done();
+        waitForDebounce().then(() => {
+          assert.equal(runCommandsSpy.getLastRunCommands().length, 2, 'Expected only two commands to run');
+          assert.equal(runCommandsSpy.getLastRunCommands()[0].command, 'vendor/bin/phpunit');
+          assert.deepEqual(runCommandsSpy.getLastRunCommands()[0].args, ['tests/unit/src/ClassTest.php']);
+          assert.equal(runCommandsSpy.getLastRunCommands()[1].command, 'vendor/bin/phpunit');
+          assert.deepEqual(
+            runCommandsSpy.getLastRunCommands()[1].args,
+            ['-c', 'phpunit-integration.xml', 'tests/integration/src/ClassTest.php'],
+          );
+          done();
+        });
       });
     });
   });