Basic version

.jshintrc

@@ -23,6 +23,8 @@
     "browser": true,
 
     "globals": {
-        "io": false
+        "io": false,
+        "describe": false,
+        "it": false
     }
 }

Makefile

@@ -1,4 +1,7 @@
 lint:
 	@./node_modules/.bin/jshint .
 
-.PHONY: lint
+test:
+	@./node_modules/.bin/mocha --reporter spec
+
+.PHONY: lint test

lib/tail.js

@@ -0,0 +1,25 @@
+(function () {
+    'use strict';
+
+    var EventEmitter = require('events').EventEmitter;
+    var util = require('util');
+    var spawn = require('child_process').spawn;
+
+    var Tail = function (path) {
+        EventEmitter.call(this);
+
+        var self = this;
+        var tail = spawn('tail', ['-F'].concat(path));
+
+        tail.stdout.on('data', function (data) {
+            var line = data.toString('utf-8');
+            self.emit('line', line);
+        });
+    };
+    util.inherits(Tail, EventEmitter);
+
+
+    module.exports = function (path) {
+        return new Tail(path);
+    };
+})();

package.json

@@ -15,7 +15,10 @@
         "cookie": "0.1.0"
     },
     "devDependencies": {
-        "jshint": "~2.1.10"
+        "jshint": "~2.3.0",
+        "should": "~2.0.2",
+        "mocha": "~1.13.0",
+        "temp": "~0.6.0"
     },
     "repository": {
         "type": "git",

test/tail.js

@@ -0,0 +1,25 @@
+(function () {
+    'use strict';
+
+    require('should');
+
+    var fs = require('fs');
+    var tail = require('../lib/tail');
+    var temp = require('temp');
+
+    describe('tail', function () {
+        temp.track();
+
+        it('should call event line if new line appear in file', function (done) {
+            temp.open('test', function (err, info) {
+                tail(info.path).on('line', function (line) {
+                    line.should.equal('testline');
+                    done();
+                });
+
+                fs.write(info.fd, 'testline');
+                fs.close(info.fd);
+            });
+        });
+    });
+})();