Process one installment at a time in background jobs

Instead of attempting to process multiple installments at a time, which
increases the chances something might go wrong, we are now only processing
one installment at a time.

This also improves the extension's performance, because the installments
can be processed in parallel.

2 files changed, 11 insertions, 28 deletions

diff --git a/spec/jobs/solidus_subscriptions/process_installment_job_spec.rb b/spec/jobs/solidus_subscriptions/process_installment_job_spec.rb
new file mode 100644
index 0000000..4a33819
--- /dev/null
+++ b/spec/jobs/solidus_subscriptions/process_installment_job_spec.rb
@@ -0,0 +1,11 @@
+RSpec.describe SolidusSubscriptions::ProcessInstallmentJob do
+  it 'processes checkout for the installment' do
+    installment = build_stubbed(:installment)
+    checkout = instance_spy(SolidusSubscriptions::Checkout)
+    allow(SolidusSubscriptions::Checkout).to receive(:new).with(installment).and_return(checkout)
+
+    described_class.perform_now(installment)
+
+    expect(checkout).to have_received(:process)
+  end
+end
diff --git a/spec/jobs/solidus_subscriptions/process_installments_job_spec.rb b/spec/jobs/solidus_subscriptions/process_installments_job_spec.rb
deleted file mode 100644
index 111fc05..0000000
--- a/spec/jobs/solidus_subscriptions/process_installments_job_spec.rb
+++ /dev/null
@@ -1,28 +0,0 @@
-require 'spec_helper'
-
-RSpec.describe SolidusSubscriptions::ProcessInstallmentsJob do
-  let(:root_order) { create :completed_order_with_pending_payment }
-  let(:installments) do
-    traits = {
-      subscription_traits: [{
-        user: root_order.user,
-        line_item_traits: [{
-          spree_line_item: root_order.line_items.first
-        }]
-      }]
-    }
-
-    create_list(:installment, 2, traits)
-  end
-
-  describe '#perform' do
-    subject { described_class.new.perform(installments) }
-
-    it 'processes the consolidated installment' do
-      expect_any_instance_of(SolidusSubscriptions::Checkout).
-        to receive(:process).once
-
-      subject
-    end
-  end
-end