Added custom types

Necessary to validate and cast custom types in Dry Schema objects.

RuboCop was updated to ignore IP addresses in the spec since we need to confirm the IP addresses are properly cast.

Milestone: minor

.config/rubocop/config.yml

@@ -4,3 +4,6 @@ inherit_gem:
 Metrics/ParameterLists:
   Exclude:
     - lib/trmnl/api/requester.rb
+Style/IpAddresses:
+  Exclude:
+    - spec/lib/trmnl/api/types_spec.rb

lib/trmnl/api/types.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+require "dry/types"
+require "ipaddr"
+
+module TRMNL
+  module API
+    # A collection of custom types.
+    module Types
+      include Dry.Types(default: :strict)
+
+      CSSVariables = Dry::Types["array"].of(
+        Dry::Types["array"].constrained(filled: true, size: 2).of(Dry::Types["coercible.string"])
+      )
+
+      IPAddress = Constructor IPAddr
+    end
+  end
+end

spec/lib/trmnl/api/types_spec.rb

@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+require "spec_helper"
+
+RSpec.describe TRMNL::API::Types do
+  describe "CSSVariables" do
+    subject(:type) { described_class::CSSVariables }
+
+    it "answers primitive" do
+      expect(type.primitive).to eq(Array)
+    end
+
+    it "answers array of CSS variables when valid" do
+      variables = [%w[--screen-w 1040px], %w[--screen-h 780px]]
+      expect(type.call(variables)).to eq(variables)
+    end
+
+    it "answers array of coerced strings when valid" do
+      expect(type.call([[1, 2]])).to eq([%w[1 2]])
+    end
+
+    it "fails with empty constraint error" do
+      expectation = proc { type.call [[]] }
+
+      expect(&expectation).to raise_error(
+        Dry::Types::ConstraintError,
+        "[] violates constraints (filled?([]) AND size?(2, []) failed)"
+      )
+    end
+
+    it "fails with size constraint error" do
+      expectation = proc { type.call [[1, 2, 3]] }
+
+      expect(&expectation).to raise_error(
+        Dry::Types::ConstraintError,
+        "[1, 2, 3] violates constraints (size?(2, [1, 2, 3]) failed)"
+      )
+    end
+  end
+
+  describe "IPAddress" do
+    subject(:type) { described_class::IPAddress }
+
+    it "answers primitive" do
+      expect(type.primitive).to eq(IPAddr)
+    end
+
+    it "answers Version 4.0.0 address" do
+      expect(type.call("10.10.1.5")).to eq(IPAddr.new("10.10.1.5"))
+    end
+
+    it "answers Version 6.0.0 address" do
+      expect(type.call("111:a111:111:d1:0:1:111e:1111")).to eq(
+        IPAddr.new("111:a111:111:d1:0:1:111e:1111")
+      )
+    end
+  end
+end