Added unit test for image api

spec/api/api_image_spec.rb

@@ -0,0 +1,38 @@
+require 'spec_helper'
+require 'squib'
+
+describe Squib::Deck, 'images' do
+
+  context '#png' do
+     it 'calls Card#png, Dir, and progress bar' do
+      card = instance_double(Squib::Card)
+      progress = double(Squib::Progress)
+      expect(card).to receive(:png).with('foo', 0, 1, 0.5, :overlay, 0.75).once
+      expect(Dir).to receive(:chdir).with('.').and_yield.once
+      expect(progress).to receive(:start).and_yield(progress).once
+      expect(progress).to receive(:increment).once
+      Squib::Deck.new do
+        @progress_bar = progress
+        @cards = [card]
+        png file: 'foo', x: 0, y: 1, alpha: 0.5, blend: :overlay, angle: 0.75
+      end
+    end
+  end
+
+  context '#svg' do
+     it 'calls Card#svg, Dir, and progress bar' do
+      card = instance_double(Squib::Card)
+      progress = double(Squib::Progress)
+      expect(card).to receive(:svg).with('foo', '#bar', 0, 1, 20, 30, 0.5, :overlay, 0.75).once
+      expect(Dir).to receive(:chdir).with('.').and_yield.once
+      expect(progress).to receive(:start).and_yield(progress).once
+      expect(progress).to receive(:increment).once
+      Squib::Deck.new do
+        @progress_bar = progress
+        @cards = [card]
+        svg file: 'foo', id: 'bar', x: 0, y: 1, width: 20, height: 30, alpha: 0.5, blend: :overlay, angle: 0.75
+      end
+    end
+  end
+
+end