Make the default rendering destination $stdout

Author: mrkn

lib/unicode_plot/plot.rb

@@ -103,7 +103,7 @@ def annotate_row!(loc, row_index, value, color: :normal)
       end
     end
 
-    def render(out, newline: true)
+    def render(out=$stdout, newline: true)
       Renderer.render(out, self, newline)
     end
 

test/test-plot.rb

@@ -0,0 +1,20 @@
+require 'stringio'
+
+class TestPlot < Test::Unit::TestCase
+  sub_test_case("#render") do
+    test("render to $stdout when no arguments") do
+      sio = StringIO.new
+      UnicodePlot.barplot(data: {a: 23, b: 37}).render(sio)
+
+      begin
+        save_stdout, $stdout = $stdout, StringIO.new
+        UnicodePlot.barplot(data: {a: 23, b: 37}).render
+        assert do
+          sio.string == $stdout.string
+        end
+      ensure
+        $stdout = save_stdout
+      end
+    end
+  end
+end