Update rails_template and add spec*

Add `validates_uniqueness_of :last_name` to *Author* model, because the
original `validates_presence_of :name` barely works.

```ruby
context "with invalid data insert" do
  it "should render error" do
    upload_file!(:authors_invalid_db)
    expect(page).to have_content "Error:"
    expect(Author.count).to eq(0)
  end
end
```

The spec above catches an `Error: SQLite
3::ConstraintException: column name is not unique`, the really
constraint is on DB level.

```ruby
add_index "authors", ["name"], name: "index_authors_on_name", unique:
true
````

The option `:batch_transaction` controls the transaction on
model level, so I've add an rspec context "with invalid data insert on model
validation".

Author: ifyouseewendy

spec/fixtures/files/authors_invalid_model.csv

@@ -0,0 +1,3 @@
+Name,Last name,Birthday
+Jim,Doe,1986-05-01
+Jane,Roe,1986-05-01

spec/import_spec.rb

@@ -292,14 +292,41 @@ def upload_file!(name, ext='csv')
         end
       end
 
-      context "with invalid data insert" do
+      context "with invalid data insert on DB constraint" do
+        # :name field has an uniq index
         it "should render error" do
           upload_file!(:authors_invalid_db)
           expect(page).to have_content "Error:"
           expect(Author.count).to eq(0)
         end
       end
 
+      context "with invalid data insert on model validation" do
+        let(:options) { { validate: true } }
+
+        before do
+          Author.create!(name: "John", last_name: "Doe")
+        end
+
+        it "should render both successful and failed message" do
+          upload_file!(:authors_invalid_model)
+          expect(page).to have_content "Failed to import 1 author"
+          expect(page).to have_content "Successfully imported 1 author"
+          expect(Author.count).to eq(2)
+        end
+
+        context "use batch_transaction to make transaction work on model validation" do
+          let(:options) { { validate: true, batch_transaction: true } }
+
+          it "should render only the failed message" do
+            upload_file!(:authors_invalid_model)
+            expect(page).to     have_content "Failed to import 1 author"
+            expect(page).to_not have_content "Successfully imported"
+            expect(Author.count).to eq(1)
+          end
+        end
+      end
+
       context "with invalid records" do
         context "with validation" do
           it "should render error" do
@@ -402,4 +429,4 @@ def upload_file!(name, ext='csv')
 
   end
 
-end
+end

spec/support/rails_template.rb

@@ -4,7 +4,7 @@
 generate :model, 'post title:string:uniq body:text author:references'
 
 #Add validation
-inject_into_file "app/models/author.rb", "  validates_presence_of :name\n", after: "Base\n"
+inject_into_file "app/models/author.rb", "  validates_presence_of :name\n  validates_uniqueness_of :last_name\n", after: "Base\n"
 inject_into_file "app/models/post.rb", "   validates_presence_of :author\n", after: ":author\n"
 
 # Configure default_url_options in test environment