Revert "Revert "Make bower an optional dependency""

This reverts commit 0501445.

The changes introduced in `0.8.6` will be re-released as part of a major
version bump to `0.9.x`.

CHANGELOG.md

@@ -1,6 +1,10 @@
 master
 ------
 
+* Don't require `bower` installation if `bower.json` is missing [#532]
+
+[#532]: https://github.com/thoughtbot/ember-cli-rails/pull/532
+
 0.8.7
 -----
 

README.md

@@ -270,7 +270,8 @@ To configure your EmberCLI-Rails applications for Heroku:
 1. Execute `rails generate ember:heroku`.
 1. Commit the newly generated files.
 1. [Add the NodeJS buildpack][buildpack] and configure NPM to include the
-   `bower` dependency's executable file.
+   `bower` dependency's executable file (if your build process requires
+   `bower`).
 
 ```sh
 $ heroku buildpacks:clear
@@ -328,11 +329,16 @@ contains the directory or directories that contain the `bower` and `npm`
 executables.
 
 #### For faster deployments
-Place the following in your deploy/<environment>.rb
+
+Place the following in your `deploy/<environment>.rb`
+
 ```ruby
 set :linked_dirs, %w{<ember-app-name>/node_modules <ember-app-name>/bower_components}
 ```
-to avoid rebuilding all the node modules and bower components with every deploy. Replace `<ember-app-name>` with the name of your ember app (default is `frontend`).
+
+to avoid rebuilding all the node modules and bower components with every deploy.
+Replace `<ember-app-name>` with the name of your ember app (default is
+`frontend`).
 
 ## Override
 

lib/ember_cli/path_set.rb

@@ -35,6 +35,10 @@ def gemfile
       @gemfile ||= root.join("Gemfile")
     end
 
+    def bower_json
+      ember_cli_root.join("bower.json")
+    end
+
     def ember
       @ember ||= begin
         root.join("node_modules", "ember-cli", "bin", "ember").tap do |path|
@@ -64,7 +68,7 @@ def build_error_file
     def bower
       @bower ||= begin
         path_for_executable("bower").tap do |bower_path|
-          if bower_path.blank? || !bower_path.executable?
+          if bower_json.exist? && (bower_path.blank? || !bower_path.executable?)
             fail DependencyError.new <<-MSG.strip_heredoc
                 Bower is required by EmberCLI
 

lib/ember_cli/shell.rb

@@ -41,13 +41,15 @@ def install
         clean_ember_dependencies!
       end
 
-      if paths.yarn
+      if paths.yarn.present? && Pathname.new(paths.yarn).executable?
         run! "#{paths.yarn} install"
       else
         run! "#{paths.npm} prune && #{paths.npm} install"
       end
 
-      run! "[ -f bower.json ] && #{paths.bower} prune && #{paths.bower} install"
+      if paths.bower_json.exist?
+        run! "#{paths.bower} prune && #{paths.bower} install"
+      end
     end
 
     def test

spec/lib/ember_cli/path_set_spec.rb

@@ -119,14 +119,38 @@
     end
 
     context "when it is missing from the $PATH" do
-      it "raises a helpful exception" do
-        stub_which(bower: nil)
+      context "bower.json exists" do
+        it "raises a helpful exception" do
+          create_file(ember_cli_root.join("bower.json"))
+          stub_which(bower: nil)
+          path_set = build_path_set
+
+          expect { path_set.bower }.
+            to raise_error(EmberCli::DependencyError, /bower is required/i)
+        end
+
+        context "bower.json is missing" do
+          it "returns nil" do
+            stub_which(bower: nil)
+            path_set = build_path_set
+
+            bower = path_set.bower
+
+            expect(bower).to be_nil
+          end
+        end
+      end
+    end
+  end
 
-        path_set = build_path_set
+  describe "#bower_json" do
+    it "is a child of #root" do
+      app = build_app(name: "foo")
+      path_set = build_path_set(app: app)
 
-        expect { path_set.bower }.
-          to raise_error(EmberCli::DependencyError, /bower is required/i)
-      end
+      bower_json = path_set.bower_json
+
+      expect(bower_json).to eq ember_cli_root.join("bower.json")
     end
   end
 
@@ -164,12 +188,6 @@
   end
 
   describe "#yarn" do
-    it "is not enabled by default" do
-      path_set = build_path_set
-
-      expect(path_set.yarn).to be nil
-    end
-
     it "can be overridden" do
       fake_yarn = create_executable(ember_cli_root.join("yarn"))
       app = build_app(options: { yarn_path: fake_yarn.to_s })
@@ -185,11 +203,23 @@
       stub_which(yarn: fake_yarn.to_s)
       app = build_app(options: { yarn: true })
       path_set = build_path_set(app: app)
+      create_executable(fake_yarn)
 
       yarn = path_set.yarn
 
       expect(yarn).to eq(fake_yarn).and(be_executable)
     end
+
+    context "when the executable isn't installed on the system" do
+      it "returns nil" do
+        stub_which(yarn: nil)
+        path_set = build_path_set
+
+        yarn = path_set.yarn
+
+        expect(yarn).to be_nil
+      end
+    end
   end
 
   describe "#node_modules" do