Builder throws an error when a watched input directory is missing

CHANGELOG.md

@@ -1,5 +1,6 @@
 # master
 
+* Builder throws an error when a watched input directory is missing
 * Rework watcher
 * Pull broccoli-sane-watcher functionality into core
 * Update findup-sync dependency

lib/builder.js

@@ -51,6 +51,10 @@ function Builder(outputNode, options) {
   // This populates this.nodeWrappers as a side effect
   this.outputNodeWrapper = this.makeNodeWrapper(this.outputNode)
 
+  // Catching missing directories here helps prevent later errors when we set
+  // up the watcher.
+  this.checkInputPathsExist()
+
   this.setupTmpDirs()
 
   // Now that temporary directories are set up, we need to run the rest of the
@@ -210,6 +214,21 @@ Builder.prototype.makeNodeWrapper = function(node, _stack) {
 
 Builder.prototype.features = broccoliNodeInfo.features
 
+Builder.prototype.checkInputPathsExist = function() {
+  // We might consider checking this.unwatchedPaths as well.
+  for (var i = 0; i < this.watchedPaths.length; i++) {
+    var isDirectory
+    try {
+      isDirectory = fs.statSync(this.watchedPaths[i]).isDirectory()
+    } catch (err) {
+      throw new Builder.BuilderError('Directory not found: ' + this.watchedPaths[i])
+    }
+    if (!isDirectory) {
+      throw new Builder.BuilderError('Not a directory: ' + this.watchedPaths[i])
+    }
+  }
+};
+
 Builder.prototype.setupTmpDirs = function() {
   // Create temporary directories for each node:
   //

test/builder_test.js

@@ -213,14 +213,26 @@ describe('Builder', function() {
       expect(builder.watchedPaths).to.deep.equal(['test/fixtures/basic'])
     })
 
-    it('fails when a source directory doesn\'t exist', function() {
+    it('fails construction when a watched source directory doesn\'t exist', function() {
+      expect(function() {
+        new Builder(new broccoliSource.WatchedDir('test/fixtures/doesnotexist'))
+      }).to.throw(Builder.BuilderError, 'Directory not found: test/fixtures/doesnotexist')
+    })
+
+    it('fails construction when a watched source directory is a file', function() {
+      expect(function() {
+        new Builder(new broccoliSource.WatchedDir('test/fixtures/basic/foo.txt'))
+      }).to.throw(Builder.BuilderError, 'Not a directory: test/fixtures/basic/foo.txt')
+    })
+
+    it('fails when an unwatched source directory doesn\'t exist', function() {
       builder = new Builder(new broccoliSource.UnwatchedDir('test/fixtures/doesnotexist'))
       // Note: `ENOENT:` or `ENOENT,` depending on Node version
       return expect(builder.build()).to.be.eventually.rejectedWith(Builder.BuildError,
         /test\/fixtures\/doesnotexist: ENOENT. no such file or directory/)
     })
 
-    it('fails when a source directory is a file', function() {
+    it('fails when an unwatched source directory is a file', function() {
       builder = new Builder(new broccoliSource.UnwatchedDir('test/fixtures/basic/foo.txt'))
       return expect(builder.build()).to.be.eventually.rejectedWith(Builder.BuildError,
         /test\/fixtures\/basic\/foo\.txt: Not a directory/)