Tests for both new and old watch syntax

.gitignore

@@ -8,4 +8,5 @@ coverage
 *.orig
 .idea
 sandbox
-test/out-fixtures/*
+test/out-fixtures/*
+test/watch-*.txt

index.js

@@ -31,7 +31,7 @@ Gulp.prototype.watch = function (glob, opt, fn) {
   if (Array.isArray(fn) || typeof fn === 'string') {
     task = fn;
     fn = function () {
-      this.start(task);
+      inst.start(task);
     };
   }
   return vfs.watch(glob, opt, fn);

test/watch.js

@@ -0,0 +1,128 @@
+'use strict';
+
+var gulp = require('../');
+var fs = require('fs');
+var path = require('path');
+
+var should = require('should');
+require('mocha');
+
+describe('gulp', function() {
+  describe('watch()', function() {
+    var tempFileContent = 'A test generated this file and it is safe to delete';
+
+    var writeTimeout = 125; // Wait for it to get to the filesystem
+    var writeFile = function (name, content, cb) {
+      fs.writeFile(name, content, cb);
+    };
+    var writeFileWait = function (name, content, cb) {
+      setTimeout(function () {
+        fs.writeFile(name, content, cb);
+      }, writeTimeout);
+    };
+
+    it('should call the function when file changes: no options', function(done) {
+
+      // arrange
+      var tempFile = './test/watch-func.txt';
+      writeFile(tempFile, tempFileContent, function () {
+
+        // assert: it works if it calls done
+        gulp.watch(tempFile, function (evt) {
+          should.exist(evt);
+          should.exist(evt.path);
+          should.exist(evt.type);
+          evt.type.should.equal('changed');
+          evt.path.should.equal(path.resolve(tempFile));
+          done();
+        });
+
+        // act: change file
+        writeFileWait(tempFile, tempFileContent+' changed');
+      });
+    });
+
+    it('should call the function when file changes: w/ options', function(done) {
+      // arrange
+      var tempFile = './test/watch-func-options.txt';
+      writeFile(tempFile, tempFileContent, function () {
+
+        // assert: it works if it calls done
+        gulp.watch(tempFile, {debounceDelay:5}, function (evt) {
+          should.exist(evt);
+          should.exist(evt.path);
+          should.exist(evt.type);
+          evt.type.should.equal('changed');
+          evt.path.should.equal(path.resolve(tempFile));
+          done();
+        });
+
+        // act: change file
+        writeFileWait(tempFile, tempFileContent+' changed');
+      });
+    });
+
+    it('should run a task by name: no options', function(done) {
+      // arrange
+      var tempFile = './test/watch-task.txt';
+      var taskName = 'run-task';
+      var a = 0;
+      var timeout = writeTimeout * 2.5;
+
+      writeFile(tempFile, tempFileContent, function () {
+
+        gulp.task(taskName, function () {
+          a++;
+        });
+
+        // assert
+        setTimeout(function () {
+          a.should.equal(1);
+
+          gulp.reset();
+          done();
+        }, timeout);
+
+        // it works if it calls the task
+        gulp.watch(tempFile, taskName);
+
+        // act: change file
+        writeFileWait(tempFile, tempFileContent+' changed');
+      });
+    });
+
+    it('should run many tasks: w/ options', function(done) {
+      // arrange
+      var tempFile = './test/watch-task-options.txt';
+      var task1 = 'task1';
+      var task2 = 'task2';
+      var a = 0;
+      var timeout = writeTimeout * 2.5;
+
+      writeFile(tempFile, tempFileContent, function () {
+
+        gulp.task(task1, function () {
+          a++;
+        });
+        gulp.task(task2, function () {
+          a += 10;
+        });
+
+        // assert
+        setTimeout(function () {
+          a.should.equal(11); // task1 and task2
+
+          gulp.reset();
+          done();
+        }, timeout);
+
+        // it works if it calls the task
+        gulp.watch(tempFile, {debounceDelay:timeout/2}, [task1,task2]);
+
+        // act: change file
+        writeFileWait(tempFile, tempFileContent+' changed');
+      });
+    });
+
+  });
+});