Added display model

Necessary to model the API response payload.

lib/trmnl/api/models/display.rb

@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+module TRMNL
+  module API
+    module Models
+      # Models data for API display responses.
+      Display = Struct.new(
+        :filename,
+        :firmware_url,
+        :image_url,
+        :image_url_timeout,
+        :refresh_rate,
+        :reset_firmware,
+        :special_function,
+        :update_firmware
+      ) do
+        def self.for(attributes) = new(**attributes)
+
+        def initialize(**)
+          super
+          apply_defaults
+          freeze
+        end
+
+        def to_json(*) = to_h.to_json(*)
+
+        private
+
+        def apply_defaults
+          self[:image_url_timeout] ||= 0
+          self[:refresh_rate] ||= 300
+          self[:reset_firmware] ||= false
+          self[:update_firmware] ||= false
+          self[:special_function] ||= "sleep"
+        end
+      end
+    end
+  end
+end

spec/lib/trmnl/api/models/display_spec.rb

@@ -0,0 +1,61 @@
+# frozen_string_literal: true
+
+require "spec_helper"
+
+RSpec.describe TRMNL::API::Models::Display do
+  subject(:model) { described_class.new }
+
+  describe ".for" do
+    let :attributes do
+      {
+        filename: "test.bmp",
+        firmware_url: "https://test.io/FW1.4.8.bin",
+        image_url: "https://test.io/images/test.bmp",
+        refresh_rate: 3200,
+        reset_firmware: false,
+        special_function: "restart_playlist",
+        update_firmware: true
+      }
+    end
+
+    it "answers record for attributes" do
+      expect(described_class.for(attributes)).to eq(described_class[**attributes])
+    end
+  end
+
+  describe "#initialize" do
+    it "answers default attributes" do
+      expect(model.to_h).to eq(
+        filename: nil,
+        firmware_url: nil,
+        image_url: nil,
+        image_url_timeout: 0,
+        refresh_rate: 300,
+        reset_firmware: false,
+        special_function: "sleep",
+        update_firmware: false
+      )
+    end
+
+    it "is frozen" do
+      expect(model.frozen?).to be(true)
+    end
+  end
+
+  describe "#to_json" do
+    it "answers JSON" do
+      payload = JSON model.to_json, symbolize_names: true
+
+      expect(payload).to eq(
+        filename: nil,
+        firmware_url: nil,
+        image_url: nil,
+        image_url_timeout: 0,
+        refresh_rate: 300,
+        reset_firmware: false,
+        special_function: "sleep",
+        update_firmware: false
+      )
+    end
+  end
+end