Only Allow Principal Investigators Access to Protocol Form

This restricts the ability of users who aren't principal investigators
such that they cannot access the form to create a new study protocol. A
principal investigator must be the type of user to create this
information.

app/controllers/study_protocols_controller.rb

@@ -1,6 +1,11 @@
 class StudyProtocolsController < ApplicationController
   def new
-    @study_protocol = StudyProtocol.new(study: study)
+    if current_user.principal_investigator?
+      @study_protocol = StudyProtocol.new(study: study)
+    else
+      flash[:alert] = "Only Principal Investigators may create study protocols"
+      redirect_back(fallback_location: root_path)
+    end
   end
 
   def create

spec/system/create_study_protocol_spec.rb

@@ -2,7 +2,7 @@
 
 RSpec.describe "Creating a study protocol", type: :system do
   scenario "Successfully adding a protocol" do
-    user = create :user
+    user = create :user, :principal_investigator
     sign_in user
 
     study = create :study
@@ -16,4 +16,18 @@
       expect(page).to have_content "Ask how they are feeling."
     end
   end
+
+  scenario "Co-investigators cannot create a study protocol" do
+    user = create :user, :co_investigator
+    sign_in user
+
+    study = create :study
+    visit new_study_study_protocol_path(study)
+
+    within(".alert-danger") do
+      expect(page).to have_content "Only Principal Investigators may create study protocols"
+    end
+
+    expect(page).to have_current_path root_path
+  end
 end