Enable all feature flags by default in specs

Otherwise some features would go untested in non-specific contexts

I did need to disable the
`gitlab_git_diff_size_limit_increase`-feature in some specs since we
depend on diffs being expandable while the file we are testing on is
smaller than the increased limit.

spec/features/merge_requests/conflicts_spec.rb

@@ -4,6 +4,11 @@ feature 'Merge request conflict resolution', js: true, feature: true do
   let(:user) { create(:user) }
   let(:project) { create(:project) }
+  before do
+    # In order to have the diffs collapsed, we need to disable the increase feature
+    stub_feature_flags(gitlab_git_diff_size_limit_increase: false)
+  end
+
   def create_merge_request(source_branch)
     create(:merge_request, source_branch: source_branch, target_branch: 'conflict-start', source_project: project) do |mr|
       mr.mark_as_unmergeable

spec/features/projects/diffs/diff_show_spec.rb

@@ -110,6 +110,10 @@ feature 'Diff file viewer', :js, feature: true do
   context 'binary file that appears to be text in the first 1024 bytes' do
     before do
+      # The file we're visiting is smaller than 10 KB and we want it collapsed
+      # so we need to disable the size increase feature.
+      stub_feature_flags(gitlab_git_diff_size_limit_increase: false)
+
       visit_commit('7b1cf4336b528e0f3d1d140ee50cafdbc703597c')
     end

spec/lib/gitlab/git/diff_spec.rb

@@ -34,7 +34,7 @@ EOT
   describe 'size limit feature toggles' do
     context 'when the feature gitlab_git_diff_size_limit_increase is enabled' do
       before do
-        Feature.enable('gitlab_git_diff_size_limit_increase')
+        stub_feature_flags(gitlab_git_diff_size_limit_increase: true)
       end
       it 'returns 200 KB for size_limit' do
@@ -48,7 +48,7 @@ EOT
     context 'when the feature gitlab_git_diff_size_limit_increase is disabled' do
       before do
-        Feature.disable('gitlab_git_diff_size_limit_increase')
+        stub_feature_flags(gitlab_git_diff_size_limit_increase: false)
       end
       it 'returns 100 KB for size_limit' do

spec/spec_helper.rb

@@ -59,6 +59,7 @@ RSpec.configure do |config|
   config.include ApiHelpers, :api
   config.include Gitlab::Routing, type: :routing
   config.include MigrationsHelpers, :migration
+  config.include StubFeatureFlags
   config.infer_spec_type_from_file_location!
@@ -79,6 +80,8 @@ RSpec.configure do |config|
   config.before(:example) do
     # Skip pre-receive hook check so we can use the web editor and merge.
     allow_any_instance_of(Gitlab::Git::Hook).to receive(:trigger).and_return([true, nil])
+    # Enable all features by default for testing
+    allow(Feature).to receive(:enabled?) { true }
   end
   config.before(:example, :request_store) do

spec/support/stub_feature_flags.rb

+module StubFeatureFlags
+  def stub_feature_flags(features)
+    features.each do |feature_name, enabled|
+      allow(Feature).to receive(:enabled?).with(feature_name) { enabled }
+      allow(Feature).to receive(:enabled?).with(feature_name.to_s) { enabled }
+    end
+  end
+end