implement Ferrum::RGBA class

Author: Mifrill

lib/ferrum/rbga.rb

@@ -0,0 +1,38 @@
+module Ferrum
+  class RGBA
+    def initialize(red, green, blue, alpha)
+      self.red = red
+      self.green = green
+      self.blue = blue
+      self.alpha = alpha
+
+      validate
+    end
+
+    def to_h
+      { r: red, g: green, b: blue, a: alpha }
+    end
+
+    private
+
+    attr_accessor :red, :green, :blue, :alpha
+
+    def validate
+      [red, green, blue].each(&method(:validate_color))
+      validate_alpha
+    end
+
+    def validate_color(value)
+      return if value && value.is_a?(Integer) && Range.new(0, 255).include?(value)
+
+      raise ArgumentError, "Wrong value of #{value} should be Integer from 0 to 255"
+    end
+
+    def validate_alpha
+      return if alpha && alpha.is_a?(Float) && Range.new(0.0, 1.0).include?(alpha)
+
+      raise ArgumentError,
+            "Wrong alpha value #{alpha} should be Float between 0.0 (fully transparent) and 1.0 (fully opaque)"
+    end
+  end
+end

spec/rbga_spec.rb

@@ -0,0 +1,46 @@
+# frozen_string_literal: true
+
+require "ferrum/rbga"
+
+module Ferrum
+  describe RGBA do
+    describe '#to_h' do
+      it { expect(RGBA.new(0, 0, 0, 0.0).to_h).to eq({ r: 0, g: 0, b: 0, a: 0.0 }) }
+      it { expect(RGBA.new(255, 255, 255, 1.0).to_h).to eq({ r: 255, g: 255, b: 255, a: 1.0 }) }
+    end
+
+    it 'raises ArgumentError for not Float value of alpha' do
+      expect {
+        RGBA.new(0, 0, 0, 0)
+      }.to raise_exception(
+             ArgumentError,
+             'Wrong alpha value 0 should be Float between 0.0 (fully transparent) and 1.0 (fully opaque)')
+    end
+
+    it 'raises ArgumentError wrong value of alpha' do
+      expect {
+        RGBA.new(0, 0, 0, 2.0)
+      }.to raise_exception(
+             ArgumentError,
+             'Wrong alpha value 2.0 should be Float between 0.0 (fully transparent) and 1.0 (fully opaque)')
+    end
+
+    it 'raises ArgumentError for wrong value of red' do
+      expect {
+        RGBA.new(-1, 0, 0, 0.0)
+      }.to raise_exception(ArgumentError, 'Wrong value of -1 should be Integer from 0 to 255')
+    end
+
+    it 'raises ArgumentError for wrong value of green' do
+      expect {
+        RGBA.new(0, 256, 0, 0.0)
+      }.to raise_exception(ArgumentError, 'Wrong value of 256 should be Integer from 0 to 255')
+    end
+
+    it 'raises ArgumentError for wrong value of blue' do
+      expect {
+        RGBA.new(0, 0, 0.0, 0.0)
+      }.to raise_exception(ArgumentError, 'Wrong value of 0.0 should be Integer from 0 to 255')
+    end
+  end
+end