Merge pull request #744 from tricknotes/support-method-for-rendering-screenshot

Support method for rendering screenshot

README.md

@@ -474,6 +474,14 @@ that this may break with more complicated expressions:
 result = page.evaluate_script('4 + 4');
 ```
 
+### Saving screenshot
+
+In drivers which support it, you can save screenshot:
+
+```ruby
+page.save_screenshot('screenshot.png')
+```
+
 ### Debugging
 
 It can be useful to take a snapshot of the page as it currently is and take a

lib/capybara/driver/base.rb

@@ -27,6 +27,10 @@ class Capybara::Driver::Base
     raise Capybara::NotSupportedByDriverError
   end
 
+  def save_screenshot(path, options={})
+    raise Capybara::NotSupportedByDriverError
+  end
+
   def response_headers
     raise Capybara::NotSupportedByDriverError
   end

lib/capybara/selenium/driver.rb

@@ -62,6 +62,10 @@ class Capybara::Selenium::Driver < Capybara::Driver::Base
     browser.execute_script "return #{script}"
   end
 
+  def save_screenshot(path, options={})
+    browser.save_screenshot(path)
+  end
+
   def reset!
     # Use instance variable directly so we avoid starting the browser just to reset the session
     if @browser

lib/capybara/session.rb

@@ -41,7 +41,7 @@ module Capybara
       :body, :html, :current_url, :current_host, :evaluate_script, :source,
       :visit, :within, :within_fieldset, :within_table,
       :within_frame, :within_window, :current_path, :save_page,
-      :save_and_open_page, :reset_session!
+      :save_and_open_page, :save_screenshot, :reset_session!
     ]
     DSL_METHODS = NODE_METHODS + SESSION_METHODS
 
@@ -286,6 +286,16 @@ module Capybara
       Capybara.save_and_open_page(body, file_name)
     end
 
+    ##
+    #
+    # Save a screenshot of page
+    #
+    # @param  [String] path    A string of image path
+    # @option [Hash]   options Options for saving screenshot
+    def save_screenshot(path, options={})
+      driver.save_screenshot(path, options)
+    end
+
     def document
       @document ||= Capybara::Node::Document.new(self, driver)
     end

lib/capybara/spec/driver.rb

@@ -324,3 +324,19 @@ shared_examples_for "driver with referer support" do
     @driver.body.should match %r{http://.*/referer_base}
   end
 end
+
+shared_examples_for "driver with screenshot support" do
+  describe '#save_screenshot' do
+    let(:image_path) { File.join(Dir.tmpdir, 'capybara-screenshot.png') }
+
+    before do
+      @driver.visit '/'
+      @driver.save_screenshot image_path
+    end
+
+    it "should generate PNG file" do
+      magic = File.read(image_path, 4)
+      magic.should eq "\x89PNG"
+    end
+  end
+end

lib/capybara/spec/session/screenshot.rb

@@ -0,0 +1,29 @@
+shared_examples_for "session with screenshot support" do
+  describe "#save_screenshot" do
+    let(:image_path) { File.join(Dir.tmpdir, 'capybara-screenshot.png') }
+
+    before do
+      @session.visit '/'
+      @session.save_screenshot image_path
+    end
+
+    it "should generate PNG file" do
+      magic = File.read(image_path, 4)
+      magic.should eq "\x89PNG"
+    end
+  end
+end
+
+shared_examples_for "session without screenshot support" do
+  describe "#save_screenshot" do
+    before do
+      @session.visit('/')
+    end
+
+    it "should raise an error" do
+      running {
+        @session.save_screenshot 'raise_error.png'
+      }.should raise_error(Capybara::NotSupportedByDriverError)
+    end
+  end
+end

spec/driver/selenium_driver_spec.rb

@@ -13,6 +13,7 @@ describe Capybara::Selenium::Driver do
   it_should_behave_like "driver without status code support"
   it_should_behave_like "driver with cookies support"
   it_should_behave_like "driver with referer support"
+  it_should_behave_like "driver with screenshot support"
 
   unless RbConfig::CONFIG['host_os'] =~ /mswin|mingw/
     it "should not interfere with forking child processes" do

spec/dsl_spec.rb

@@ -213,6 +213,7 @@ describe Capybara::DSL do
 
     it_should_behave_like "session"
     it_should_behave_like "session without javascript support"
+    it_should_behave_like "session without screenshot support"
 
     it "should be possible to include it in another class" do
       klass = Class.new do

spec/session/rack_test_session_spec.rb

@@ -55,6 +55,7 @@ describe Capybara::Session do
 
     it_should_behave_like "session"
     it_should_behave_like "session without javascript support"
+    it_should_behave_like "session without screenshot support"
     it_should_behave_like "session with headers support"
     it_should_behave_like "session with status code support"
   end

spec/session/selenium_session_spec.rb

@@ -20,6 +20,7 @@ describe Capybara::Session do
 
     it_should_behave_like "session"
     it_should_behave_like "session with javascript support"
+    it_should_behave_like "session with screenshot support"
     it_should_behave_like "session without headers support"
     it_should_behave_like "session without status code support"
   end