How to specify the location of the chromedriver binary

Solution 1 - Selenium::WebDriver::Chrome.driver_path=

There is a Selenium::WebDriver::Chrome.driver_path= method that allows specifying of the chromedriver binary:

require 'watir'

# Specify the driver path
chromedriver_path = File.join(File.absolute_path('../..', File.dirname(__FILE__)),"browsers","chromedriver.exe")
Selenium::WebDriver::Chrome.driver_path = chromedriver_path

# Start the browser as normal
b = Watir::Browser.new :chrome
b.goto 'www.google.com'
b.close

Solution 2 - Specify :driver_path during browser initialization

As an alternative, you can also specify the driver path when initializing the browser. This is a bit nicer in that you do not need to have Selenium code, but would be repetitive if you initialize the browser in different places.

# Determine the driver path
chromedriver_path = File.join(File.absolute_path('../..', File.dirname(__FILE__)),"browsers","chromedriver.exe")

# Initialize the browser with the driver path
browser = Watir::Browser.new :chrome, driver_path: chromedriver_path

Solution 3 - Update ENV['PATH']

When I had originally answered this question, for whatever reason, I had not been able to get the above solution to work. Setting the value did not appear to be used when Selenium-WebDriver started the driver in. While the first solution is the recommended approach, this is an alternative.

Another option is to programmatically add the desired directory to the path, which is stored in the ENV['PATH']. You can see in the Selenium::WebDriver::Platform that the binary is located by checking if the executable exists in any of the folders in the path (from version 2.44.0):

def find_binary(*binary_names)
  paths = ENV['PATH'].split(File::PATH_SEPARATOR)
  binary_names.map! { |n| "#{n}.exe" } if windows?

  binary_names.each do |binary_name|
    paths.each do |path|
      exe = File.join(path, binary_name)
      return exe if File.executable?(exe)
    end
  end

  nil
end

To specify the folder that includes the binary, you simply need to change the ENV['PATH'] (to append the directory):

require 'watir'

# Determine the directory containing chromedriver.exe
chromedriver_directory = File.join(File.absolute_path('../..', File.dirname(__FILE__)),"browsers")

# Add that directory to the path
ENV['PATH'] = "#{ENV['PATH']}#{File::PATH_SEPARATOR}#{chromedriver_directory}"

# Start the browser as normal
b = Watir::Browser.new :chrome
b.goto 'www.google.com'
b.close

In Selenium webdriver 3.x configs, change:

caps = Selenium::WebDriver::Remote::Capabilities.chrome("chromeOptions" => {"binary" => <path to chrome (example: chrome portable)>})
Capybara::Selenium::Driver.new(app, :browser => :chrome, :driver_path => <path to chrome driver>, :desired_capabilities => caps)

driver_path: Define path to chromedriver chromedriver page

binary: Define path to binary chrome app chromepage. You can use a chrome portable to use differents versions of chrome.