Add Ferrum::Brower::Base.version method (#504)

lib/ferrum/browser/options/base.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require "singleton"
+require "open3"
 
 module Ferrum
   class Browser
@@ -12,6 +13,14 @@ def self.options
           instance
         end
 
+        # @return [String, nil]
+        def self.version
+          out, = Open3.capture2(instance.detect_path, "--version")
+          out.strip
+        rescue Errno::ENOENT
+          nil
+        end
+
         def to_h
           self.class::DEFAULT_OPTIONS
         end

spec/browser/options/chrome_spec.rb

@@ -25,4 +25,10 @@
       expect(defaults.merge_default({}, options)).not_to include("use-angle" => "metal")
     end
   end
+
+  describe ".version" do
+    it "returns an executable version" do
+      expect(described_class.version).to match(/(Chromium|Chrome) \d/)
+    end
+  end
 end