From 0a155da2734424a3843a738562dc031f947b9072 Mon Sep 17 00:00:00 2001
From: Matt-Yorkley <9029026+Matt-Yorkley@users.noreply.github.com>
Date: Tue, 25 Jun 2019 11:13:56 +0100
Subject: [PATCH 1/3] Avoid `undefined method 'order'` errors when removing
 lineitems from basket

---
 app/models/spree/calculator_decorator.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/app/models/spree/calculator_decorator.rb b/app/models/spree/calculator_decorator.rb
index 33c32c901e..32f397ad39 100644
--- a/app/models/spree/calculator_decorator.rb
+++ b/app/models/spree/calculator_decorator.rb
@@ -9,7 +9,7 @@ module Spree
         [object]
       elsif object.respond_to? :line_items
         object.line_items
-      elsif object.order.present?
+      elsif object.respond_to? :order
         object.order.line_items
       else
         [object]

From f19a6f0dec520dcbbb31619b3015bff800db105f Mon Sep 17 00:00:00 2001
From: Matt-Yorkley <9029026+Matt-Yorkley@users.noreply.github.com>
Date: Tue, 25 Jun 2019 12:19:16 +0100
Subject: [PATCH 2/3] Add tests for class_eval on Spree::Calculator private
 method #line_items_for

---
 spec/models/spree/calculator_spec.rb | 36 ++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 spec/models/spree/calculator_spec.rb

diff --git a/spec/models/spree/calculator_spec.rb b/spec/models/spree/calculator_spec.rb
new file mode 100644
index 0000000000..5caf4dca72
--- /dev/null
+++ b/spec/models/spree/calculator_spec.rb
@@ -0,0 +1,36 @@
+require 'spec_helper'
+
+module Spree
+  describe Calculator do
+    let(:calculator) { Spree::Calculator.new }
+    let!(:enterprise) { create(:enterprise) }
+    let!(:order) { create(:order) }
+    let!(:line_item) { create(:line_item, order: order) }
+    let!(:line_item2) { create(:line_item, order: order) }
+
+    before do
+      order.line_items << line_item
+      order.line_items << line_item2
+    end
+
+    describe "#line_items_for" do
+      it "returns the line item if given a line item" do
+        result = calculator.__send__(:line_items_for, line_item)
+
+        expect(result).to eq [line_item]
+      end
+
+      it "returns line items if given an order" do
+        result = calculator.__send__(:line_items_for, order)
+
+        expect(result).to eq [line_item, line_item2]
+      end
+
+      it "returns the original object if given anything else" do
+        result = calculator.__send__(:line_items_for, enterprise)
+
+        expect(result).to eq [enterprise]
+      end
+    end
+  end
+end

From 5100ad6b51f5026bd6fe07d6c176dd439dc9771d Mon Sep 17 00:00:00 2001
From: Matt-Yorkley <9029026+Matt-Yorkley@users.noreply.github.com>
Date: Tue, 25 Jun 2019 15:33:42 +0100
Subject: [PATCH 3/3] Improve #line_items_for logic and add more tests

---
 app/models/spree/calculator_decorator.rb |  2 +-
 spec/models/spree/calculator_spec.rb     | 10 +++++++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/app/models/spree/calculator_decorator.rb b/app/models/spree/calculator_decorator.rb
index 32f397ad39..5d130d86aa 100644
--- a/app/models/spree/calculator_decorator.rb
+++ b/app/models/spree/calculator_decorator.rb
@@ -9,7 +9,7 @@ module Spree
         [object]
       elsif object.respond_to? :line_items
         object.line_items
-      elsif object.respond_to? :order
+      elsif object.respond_to?(:order) && object.order.present?
         object.order.line_items
       else
         [object]
diff --git a/spec/models/spree/calculator_spec.rb b/spec/models/spree/calculator_spec.rb
index 5caf4dca72..2aa8c5d0a8 100644
--- a/spec/models/spree/calculator_spec.rb
+++ b/spec/models/spree/calculator_spec.rb
@@ -5,12 +5,14 @@ module Spree
     let(:calculator) { Spree::Calculator.new }
     let!(:enterprise) { create(:enterprise) }
     let!(:order) { create(:order) }
+    let!(:shipment) { create(:shipment) }
     let!(:line_item) { create(:line_item, order: order) }
     let!(:line_item2) { create(:line_item, order: order) }
 
     before do
       order.line_items << line_item
       order.line_items << line_item2
+      order.shipments = [shipment]
     end
 
     describe "#line_items_for" do
@@ -20,12 +22,18 @@ module Spree
         expect(result).to eq [line_item]
       end
 
-      it "returns line items if given an order" do
+      it "returns line items if given an object with line items" do
         result = calculator.__send__(:line_items_for, order)
 
         expect(result).to eq [line_item, line_item2]
       end
 
+      it "returns line items if given an object with an order" do
+        result = calculator.__send__(:line_items_for, shipment)
+
+        expect(result).to eq [line_item, line_item2]
+      end
+
       it "returns the original object if given anything else" do
         result = calculator.__send__(:line_items_for, enterprise)