Load rake tasks only once for code coverage

Apparently, Rake's way of reloading the task code confuses the code
coverage report. Code tested by rake task specs was not recognised as
covered even though it was.

spec/lib/tasks/data/truncate_data_rake_spec.rb

@@ -1,15 +1,13 @@
 # frozen_string_literal: true
 
 require 'spec_helper'
-require 'rake'
 
 RSpec.describe 'truncate_data.rake' do
+  include_context "rake"
+
   describe ':truncate' do
     context 'when months_to_keep is specified' do
       it 'truncates order cycles closed earlier than months_to_keep months ago' do
-        Rake.application.rake_require 'tasks/data/truncate_data'
-        Rake::Task.define_task(:environment)
-
         highline = instance_double(HighLine, agree: true)
         allow(HighLine).to receive(:new).and_return(highline)
 
@@ -27,7 +25,7 @@ RSpec.describe 'truncate_data.rake' do
         create(:order, order_cycle: recent_order_cycle)
 
         months_to_keep = 6
-        Rake.application.invoke_task "ofn:data:truncate[#{months_to_keep}]"
+        invoke_task "ofn:data:truncate[#{months_to_keep}]"
 
         expect(OrderCycle.all).to contain_exactly(recent_order_cycle)
       end

spec/lib/tasks/enterprises_rake_spec.rb

@@ -1,13 +1,9 @@
 # frozen_string_literal: true
 
 require 'spec_helper'
-require 'rake'
 
 RSpec.describe 'enterprises.rake' do
-  before(:all) do
-    Rake.application.rake_require("tasks/enterprises")
-    Rake::Task.define_task(:environment)
-  end
+  include_context "rake"
 
   describe ':remove_enterprise' do
     context 'when the enterprises exists' do
@@ -15,7 +11,7 @@ RSpec.describe 'enterprises.rake' do
         enterprise = create(:enterprise)
 
         expect {
-          Rake.application.invoke_task "ofn:remove_enterprise[#{enterprise.id}]"
+          invoke_task "ofn:remove_enterprise[#{enterprise.id}]"
         }.to change { Enterprise.count }.by(-1)
       end
     end
@@ -32,7 +28,7 @@ RSpec.describe 'enterprises.rake' do
         enterprise_diff.connected_apps.create
 
         expect {
-          Rake.application.invoke_task(
+          invoke_task(
             "ofn:enterprises:activate_connected_app_type[affiliate_sales_data]"
           )
         }.to change { ConnectedApps::AffiliateSalesData.count }.by(1)

spec/lib/tasks/import_product_images_rake_spec.rb

@@ -1,23 +1,15 @@
 # frozen_string_literal: true
 
 require 'spec_helper'
-require 'rake'
 
 RSpec.describe 'ofn:import:product_images' do
-  before(:all) do
-    Rake.application.rake_require("tasks/import_product_images")
-    Rake::Task.define_task(:environment)
-  end
-
-  before do
-    Rake::Task['ofn:import:product_images'].reenable
-  end
+  include_context "rake"
 
   describe 'task' do
     context "filename is blank" do
       it 'raises an error' do
         expect {
-          Rake.application.invoke_task('ofn:import:product_images')
+          invoke_task('ofn:import:product_images')
         }.to raise_error(RuntimeError,
                          'Filename required')
       end
@@ -28,7 +20,7 @@ RSpec.describe 'ofn:import:product_images' do
         allow(CSV).to receive(:read).and_return(CSV::Table.new([]))
 
         expect {
-          Rake.application.invoke_task('ofn:import:product_images["path/to/csv/file.csv"]')
+          invoke_task('ofn:import:product_images["path/to/csv/file.csv"]')
         }.to raise_error(RuntimeError, 'CSV columns reqired: ["producer", "name", "image_url"]')
       end
     end
@@ -74,7 +66,7 @@ RSpec.describe 'ofn:import:product_images' do
         OUTPUT
 
         expect {
-          Rake.application.invoke_task('ofn:import:product_images["path/to/csv/file.csv"]')
+          invoke_task('ofn:import:product_images["path/to/csv/file.csv"]')
         }.to output(expected_output).to_stdout
       end
     end

spec/lib/tasks/reset_spec.rb

@@ -1,13 +1,9 @@
 # frozen_string_literal: true
 
 require 'spec_helper'
-require 'rake'
 
 RSpec.describe "reset.rake" do
-  before(:all) do
-    Rake.application.rake_require("tasks/reset")
-    Rake::Task.define_task(:environment)
-  end
+  include_context "rake"
 
   it "clears job queues" do
     job_class = Class.new do
@@ -18,7 +14,7 @@ RSpec.describe "reset.rake" do
     queue = Sidekiq::Queue.all.first # rubocop:disable Rails/RedundantActiveRecordAllMethod
 
     expect {
-      Rake.application.invoke_task "ofn:reset_sidekiq"
+      invoke_task "ofn:reset_sidekiq"
     }.to change {
       queue.count
     }.to(0)

spec/lib/tasks/sample_data_rake_spec.rb

@@ -1,13 +1,9 @@
 # frozen_string_literal: true
 
 require 'spec_helper'
-require 'rake'
 
 RSpec.describe 'sample_data.rake' do
-  before(:all) do
-    Rake.application.rake_require 'tasks/sample_data'
-    Rake::Task.define_task(:environment)
-  end
+  include_context "rake"
 
   before do
     # Create seed data required by the sample data.
@@ -16,7 +12,7 @@ RSpec.describe 'sample_data.rake' do
   end
 
   it "creates some sample data to play with" do
-    Rake.application.invoke_task "ofn:sample_data"
+    invoke_task "ofn:sample_data"
 
     expect(EnterpriseGroup.count).to eq 1
     expect(Customer.count).to eq 2

spec/lib/tasks/simplecov_spec.rb

@@ -1,12 +1,9 @@
 # frozen_string_literal: true
 
 require 'spec_helper'
-require 'rake'
 
 RSpec.describe "simplecov.rake" do
-  before(:all) do
-    Rake.application.rake_require("tasks/simplecov")
-  end
+  include_context "rake"
 
   describe "simplecov:collate_results" do
     context "when there are reports to merge" do
@@ -17,7 +14,7 @@ RSpec.describe "simplecov.rake" do
           output_dir = File.join(tmp_dir, "output")
 
           expect {
-            Rake.application.invoke_task(
+            invoke_task(
               "simplecov:collate_results[#{input_dir},#{output_dir}]"
             )
           }.to change { Dir.exist?(output_dir) }.

spec/lib/tasks/users_rake_spec.rb

@@ -4,18 +4,14 @@ require 'spec_helper'
 require 'rake'
 
 RSpec.describe 'users.rake' do
-  before do
-    Rake.application.rake_require 'tasks/users'
-    Rake::Task.define_task(:environment)
-    Rake::Task['ofn:remove_enterprise_limit'].reenable
-  end
+  include_context "rake"
 
   describe ':remove_enterprise_limit' do
     context 'when the user exists' do
       let(:user) { create(:user) }
 
       it 'sets the enterprise_limit to the maximum integer' do
-        Rake.application.invoke_task "ofn:remove_enterprise_limit[#{user.id}]"
+        invoke_task "ofn:remove_enterprise_limit[#{user.id}]"
 
         expect(user.reload.enterprise_limit).to eq(2_147_483_647)
       end
@@ -24,7 +20,7 @@ RSpec.describe 'users.rake' do
     context 'when the user does not exist' do
       it 'raises' do
         expect {
-          Rake.application.invoke_task "ofn:remove_enterprise_limit[123]"
+          invoke_task "ofn:remove_enterprise_limit[123]"
         }.to raise_error(ActiveRecord::RecordNotFound)
       end
     end

spec/support/shared_contexts/rake.rb

@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+# Let this context take of Rake testing gotchas.
+#
+# ```rb
+# RSpec.describe "my_task.rake" do
+#   include_context "rake"
+#   # ..
+# ```
+#
+shared_context "rake" do
+  before(:all) do
+    # Make sure that Rake tasks are only loaded once.
+    # Otherwise we lose code coverage data.
+    if Rake::Task.tasks.empty?
+      Openfoodnetwork::Application.load_tasks
+      Rake::Task.define_task(:environment)
+    end
+  end
+
+  # Use the same task string as you would on the command line.
+  #
+  # ```rb
+  # invoke_task "example:task[arg1,arg2]"
+  # ```
+  #
+  # This helper makes sure that you can run a task multiple times,
+  # even within the same test example.
+  def invoke_task(task_string)
+    Rake.application.invoke_task(task_string)
+  ensure
+    name, _args = Rake.application.parse_task_string(task_string)
+    Rake::Task[name].reenable
+  end
+end