All textbook chapters must have name and asset_path

Previously, for a textbook with only one chapter, we allowed that chapter to
not have a title -- under the assumption that it would be shown as a monolithic
textbook, instead of a chaptered textbook. However, the UI doesn't support that
idea, the code was getting a bit messy, and there was no real benefit to the idea
of not having to specify a chapter title. This commit removes that special case,
and ensures that all textbook chapters must have a name and an asset path.

cms/static/coffee/spec/views/textbook_spec.coffee

@@ -130,10 +130,13 @@ describe "CMS.Views.EditTextbook", ->
         it "should save properly", ->
             @view.render()
             @view.$("input[name=textbook-name]").val("starfish")
+            @view.$("input[name=chapter1-name]").val("wallflower")
             @view.$("input[name=chapter1-asset-path]").val("foobar")
             @view.$("form").submit()
             expect(@model.get("name")).toEqual("starfish")
-            expect(@model.get("chapters").at(0).get("asset_path")).toEqual("foobar")
+            chapter = @model.get("chapters").first()
+            expect(chapter.get("name")).toEqual("wallflower")
+            expect(chapter.get("asset_path")).toEqual("foobar")
             expect(@model.save).toHaveBeenCalled()
 
         it "should not save on invalid", ->
@@ -151,7 +154,8 @@ describe "CMS.Views.EditTextbook", ->
             @view.$("input[name=chapter1-asset-path]").val("foobar.pdf")
             @view.$(".action-cancel").click()
             expect(@model.get("name")).not.toEqual("starfish")
-            expect(@model.get("chapters").first().get("asset_path")).not.toEqual("foobar")
+            chapter = @model.get("chapters").first()
+            expect(chapter.get("asset_path")).not.toEqual("foobar")
             expect(@model.save).not.toHaveBeenCalled()
 
         it "should be possible to correct validation errors", ->

cms/static/js/models/textbook.js

@@ -68,17 +68,9 @@ CMS.Models.Textbook = Backbone.AssociatedModel.extend({
         }
         if (attrs.chapters.length === 0) {
             return {
-                message: "Please add at least one asset",
+                message: "Please add at least one chapter",
                 attributes: {chapters: true}
             };
-        } else if (attrs.chapters.length === 1) {
-            // only asset_path is required: we don't need a name
-            if (!attrs.chapters.first().get('asset_path')) {
-                return {
-                    message: "Please add at least one asset",
-                    attributes: {chapters: true}
-                };
-            }
         } else {
             // validate all chapters
             var invalidChapters = [];

cms/static/js/views/textbook.js

@@ -143,23 +143,12 @@ CMS.Views.EditTextbook = Backbone.View.extend({
     close: function() {
         var textbooks = this.model.collection;
         this.remove();
-        // if the textbook has no content, remove it from the collection
-        if(this.model.isEmpty()) {
+        if(this.model.isNew()) {
+            // if the textbook has never been saved, remove it
             textbooks.remove(this.model);
-        } else {
-            // remove empty chapters from textbook
-            var chapters = this.model.get("chapters");
-            var emptyChapters = chapters.filter(function(chapter) {
-                return chapter.isEmpty(); });
-            if (chapters.length === emptyChapters.length) {
-                // make sure that there's always at least one chapter remaining
-                // in the chapterset, even if it's empty
-                emptyChapters = _.tail(emptyChapters);
-            }
-            chapters.remove(emptyChapters);
-            // don't forget to tell the model that it's no longer being edited
-            this.model.set("editing", false);
         }
+        // don't forget to tell the model that it's no longer being edited
+        this.model.set("editing", false);
         return this;
     }
 });