Added ability to force interval value by setting `CHOKIDAR_INTERVAL… (#557)

* Added ability to force `interval` value by setting `CHOKIDAR_INTERVAL` env variable.

* Parse to integer.

* Simply if (envInterval) should be fine in this case, since we're not contending with false as a valid potential value.

* Combine lines.

Author: YAmikep

CHANGELOG.md

@@ -1,3 +1,6 @@
+* Added ability to force `interval` value by setting `CHOKIDAR_INTERVAL`
+  env variable
+
 # Chokidar 1.6.0 (Jun 22, 2016)
 * Added ability for force `usePolling` mode by setting `CHOKIDAR_USEPOLLING`
   env variable

README.md

@@ -183,7 +183,8 @@ non-standard situations. Setting to `true` explicitly on OS X overrides the
 `useFsEvents` default. You may also set the CHOKIDAR_USEPOLLING env variable
 to true (1) or false (0) in order to override this option.
 * _Polling-specific settings_ (effective when `usePolling: true`)
-  * `interval` (default: `100`). Interval of file system polling.
+  * `interval` (default: `100`). Interval of file system polling. You may also 
+    set the CHOKIDAR_INTERVAL env variable to override this option.
   * `binaryInterval` (default: `300`). Interval of file system
   polling for binary files.
   ([see list of binary extensions](https://github.com/sindresorhus/binary-extensions/blob/master/binary-extensions.json))

index.js

@@ -105,6 +105,10 @@ function FSWatcher(_opts) {
       opts.usePolling = !!envLower
     }
   }
+  var envInterval = process.env.CHOKIDAR_INTERVAL;
+  if (envInterval) {
+    opts.interval = parseInt(envInterval);
+  }
 
   // Editor atomic write normalization enabled by default with fs.watch
   if (undef('atomic')) opts.atomic = !opts.usePolling && !opts.useFsEvents;

test.js

@@ -1877,5 +1877,20 @@ function runTests(baseopts) {
         });
       });
     });
+    describe('CHOKIDAR_INTERVAL', function() {
+      afterEach(function() {
+        delete process.env.CHOKIDAR_INTERVAL;
+      });
+
+      it('should make options.interval = CHOKIDAR_INTERVAL when it is set', function(done) {
+        options.interval = 100;
+        process.env.CHOKIDAR_INTERVAL = 1500;
+
+        watcher = chokidar.watch(fixturesPath, options).on('ready', function() {
+          watcher.options.interval.should.be.equal(1500);
+          done();
+        });
+      });
+    });
   });
 }