pr cleanups and add failure test case

app/controllers/api/v1/project_preferences_controller.rb

@@ -7,6 +7,7 @@ class Api::V1::ProjectPreferencesController < Api::ApiController
   extra_schema_actions :update_settings
   schema_type :json_schema
   before_action :find_upp_for_update_settings, only: [:update_settings]
+  before_action :find_project, only: [:read_settings]
 
   def read_settings
     skip_policy_scope
@@ -20,7 +21,9 @@ def update_settings
     read_and_update_settings_response
   end
 
-  private
+  def find_project
+    @project = Project.find(params[:project_id])
+  end
 
   def find_upp_for_update_settings
     @upp = UserProjectPreference.find_by!(
@@ -35,7 +38,7 @@ def user_allowed?
   end
 
   def read_and_update_settings_response
-    set_last_modified_header if action_name == "update_settings"
+    set_last_modified_header if action_name == 'update_settings'
 
     render_json_response
   end
@@ -47,14 +50,12 @@ def set_last_modified_header
   end
 
   def render_json_response
-    if action_name == "update_settings"
+    preferences = if action_name == 'update_settings'
       preferences = UserProjectPreference.where(id: @upp.id)
     else
-      project = Project.find_by!(id: params[:project_id])
-      preferences = project.user_project_preference.where.not(email_communication: nil)
+      preferences = @project.user_project_preference.where.not(email_communication: nil)
       preferences = params[:user_id].present? ? preferences.where(user_id: params[:user_id]) : preferences
-    end
-
+    end  
     render(
       status: :ok,
       json_api: serializer.resource({}, preferences, context)

app/models/project.rb

@@ -15,7 +15,7 @@ class Project < ApplicationRecord
   has_many :tutorials
   has_many :field_guides, dependent: :destroy
   belongs_to :organization
-  has_many :user_project_preference
+  has_many :user_project_preference, dependent: :destroy
   # uses the activated_state enum on the workflow
   has_many :workflows,
     -> { where(serialize_with_project: true).active},

spec/controllers/api/v1/project_preferences_controller_spec.rb

@@ -202,6 +202,7 @@
     let!(:project) { create(:project, owner: authorized_user) }
     let!(:upp) { create(:user_project_preference, project: project) }
     let(:run_generic_read) { get :read_settings, params: { project_id: project.id, format: :json } }
+    let(:run_invalid_project) { get :read_settings, params: { project_id: 500, format: :json } }
     let(:unauthorised_user) { create(:user) }
     let(:run_unauthorised_user_read) { get :read_settings, params: { project_id: project.id, user_id: unauthorised_user.id, format: :json } }
 
@@ -214,27 +215,38 @@
       it 'responds with a 200' do
         expect(response.status).to eq(200)
       end
-  
+
       it 'returns the correct response data' do
         json_response = JSON.parse(response.body)
         expect(json_response["project_preferences"]).to be_a(Array)
         expect(json_response["project_preferences"].count).to eq(1)
       end
     end
 
+    describe 'invalid project' do
+      before do
+        default_request user_id: authorized_user.id, scopes: scopes
+        run_invalid_project
+      end
+
+      it 'responds with a 404' do
+        expect(response.status).to eq(404)
+      end
+    end
+
     describe 'user specific preferences' do
-      before(:each) do
+      before do
         default_request user_id: unauthorised_user.id, scopes: scopes
         run_unauthorised_user_read
       end
 
       it 'responds with a 200' do
         expect(response.status).to eq(200)
       end
-  
+
       it 'returns the correct response data' do
         json_response = JSON.parse(response.body)
-        expect(json_response["project_preferences"].count).to eq(0)
+        expect(json_response['project_preferences'].count).to eq(0)
       end
     end
   end