Add specs for color scheme seed

spec/models/color_schemes/seed_spec.rb

@@ -0,0 +1,17 @@
+require "rails_helper"
+
+RSpec.describe ColorSchemes::Seed do
+  describe "#seed_all" do
+    it "creates color scheme data and is idempotent" do
+      aggregate_failures do
+        expect {
+          described_class.new.seed_all
+        }.to change(ColorScheme, :count).by_at_least 100
+
+        expect {
+          described_class.new.seed_all
+        }.not_to change(ColorScheme, :count)
+      end
+    end
+  end
+end