Fix watching of entry points

Currently changes to non-partials are being picked up. This PR Fixes
that and adds addition test coverage.

Fixes #2139

bin/node-sass

@@ -250,8 +250,6 @@ function watch(options, emitter) {
     });
   };
 
-  watcher.reset(options);
-
   var gaze = new Gaze();
   gaze.add(watcher.reset(options));
   gaze.on('error', emitter.emit.bind(emitter, 'error'));

lib/watcher.js

 var grapher = require('sass-graph'),
   clonedeep = require('lodash.clonedeep'),
+  path = require('path'),
   config = {},
   watcher = {},
   graph = null;
@@ -30,8 +31,14 @@ watcher.changed = function(absolutePath) {
 
   this.reset();
 
+  if (absolutePath && path.basename(absolutePath)[0] !== '_') {
+    files.changed.push(absolutePath);
+  }
+
   graph.visitAncestors(absolutePath, function(parent) {
-    files.changed.push(parent);
+    if (path.basename(parent)[0] !== '_') {
+      files.changed.push(parent);
+    }
   });
 
   graph.visitDescendents(absolutePath, function(child) {
@@ -50,7 +57,7 @@ watcher.added = function(absolutePath) {
 
   this.reset();
 
-  if (Object.keys(graph.index).indexOf(absolutePath) !== -1) {
+  if (Object.keys(graph.index).indexOf(absolutePath) === -1) {
     files.added.push(absolutePath);
   }
 
@@ -69,7 +76,9 @@ watcher.removed = function(absolutePath) {
   };
 
   graph.visitAncestors(absolutePath, function(parent) {
-    files.changed.push(parent);
+    if (path.basename(parent)[0] !== '_') {
+      files.changed.push(parent);
+    }
   });
 
   if (Object.keys(graph.index).indexOf(absolutePath) !== -1) {

test/fixtures/watcher/main/partials/_one.scss

+@import "partials/three";
+
 .one {
   color: darkred;
 }

test/fixtures/watcher/main/partials/_two.scss

+@import "partials/three";
+
 .two {
   color: darkblue;
 }

test/fixtures/watcher/main/three.scss

+.three {
+  color: green;
+}

test/fixtures/watcher/main/two.scss

-@import "partials/two";
-
 .two {
   color: blue;
 }