Specs for photos helper

app/models/crop.rb

@@ -120,12 +120,7 @@ class Crop < ActiveRecord::Base
   # later we can choose a default photo based on different criteria,
   # eg. popularity
   def default_photo
-    # most recent photo
-    return photos.order(created_at: :desc).first if photos.any?
-
-    # Crop has no photos? Look for the most recent harvest with a photo.
-    harvest_with_photo = Harvest.where(crop_id: id).joins(:photos).order('harvests.id DESC').limit(1).first
-    harvest_with_photo.photos.first if harvest_with_photo
+    first_photo(:plantings) || first_photo(:harvests) || first_photo(:seeds)
   end
 
   # returns hash indicating whether this crop is grown in
@@ -242,4 +237,8 @@ class Crop < ActiveRecord::Base
     return unless reason_for_rejection == "other" && rejection_notes.blank?
     errors.add(:rejection_notes, "must be added if the reason for rejection is \"other\"")
   end
+
+  def first_photo(type)
+    Photo.joins(type).where("#{type}": { crop_id: id }).order("photos.created_at DESC").first
+  end
 end

spec/helpers/photos_helper_spec.rb

@@ -0,0 +1,88 @@
+require 'rails_helper'
+
+describe PhotosHelper do
+  let(:crop) { FactoryBot.create :crop }
+  let(:crop_photo) { FactoryBot.create :photo, thumbnail_url: 'crop.jpg' }
+  let(:garden) { FactoryBot.create :garden }
+  let(:garden_photo) { FactoryBot.create(:photo, thumbnail_url: 'garden.jpg') }
+  let(:planting) { FactoryBot.create :planting }
+  let(:planting_photo) { FactoryBot.create(:photo, thumbnail_url: 'planting.jpg') }
+  let(:harvest) { FactoryBot.create :harvest }
+  let(:harvest_photo) { FactoryBot.create(:photo, thumbnail_url: 'harvest.jpg') }
+  let(:seed) { FactoryBot.create :seed }
+  let(:seed_photo) { FactoryBot.create(:photo, thumbnail_url: 'seed.jpg') }
+
+  describe "crops" do
+    subject { crop_image_path(crop) }
+
+    it { is_expected.to eq 'placeholder_150.png' }
+
+    describe "with a planting" do
+      before do
+        planting.photos << planting_photo
+        crop.plantings << planting
+      end
+      it "uses planting photos" do
+        is_expected.to eq planting_photo.thumbnail_url
+      end
+    end
+
+    describe "with a harvest photos" do
+      before do
+        harvest.photos << harvest_photo
+        crop.harvests << harvest
+      end
+      it "uses harvest photos" do
+        is_expected.to eq harvest_photo.thumbnail_url
+      end
+    end
+
+    describe "uses seed photo" do
+      before do
+        seed.photos << seed_photo
+        crop.seeds << seed
+      end
+      it "uses seed photos" do
+        is_expected.to eq seed_photo.thumbnail_url
+      end
+    end
+  end
+
+  describe "gardens" do
+    subject { garden_image_path(garden) }
+    it { is_expected.to eq 'placeholder_150.png' }
+
+    describe "uses garden's own photo" do
+      before { garden.photos << garden_photo }
+      it { is_expected.to eq garden_photo.thumbnail_url }
+    end
+  end
+
+  describe 'plantings' do
+    subject { planting_image_path(planting) }
+    it { is_expected.to eq 'placeholder_150.png' }
+    describe "uses planting's own photo" do
+      before { planting.photos << planting_photo }
+      it { is_expected.to eq planting_photo.thumbnail_url }
+    end
+  end
+
+  describe 'harvests' do
+    subject { harvest_image_path(harvest) }
+    it { is_expected.to eq 'placeholder_150.png' }
+    describe "uses harvest's own photo" do
+      before { harvest.photos << harvest_photo }
+      it { is_expected.to eq harvest_photo.thumbnail_url }
+    end
+  end
+
+  describe 'seeds' do
+    subject { seed_image_path(seed) }
+    it { is_expected.to eq 'placeholder_150.png' }
+
+    describe "uses seed's own photo" do
+      before { seed.photos << seed_photo }
+      it { is_expected.to eq seed_photo.thumbnail_url }
+    end
+  end
+end