MiniProxy

A small stubbable proxy server for testing HTTP(S) interactions.

Supported Versions

• Ruby 3.0, 3.1, 3.2

Getting Started

In your Gemfile:

gem 'miniproxy'

Configure Capybara (via Chrome and Selenium) to route all requests through the server (spec/support/capybara_driver.rb):

chrome_options = Selenium::WebDriver::Chrome::Options.new
chrome_options.add_argument("--proxy-server=#{MiniProxy.host}:#{MiniProxy.port}")
chrome_options.add_argument("--ignore-certificate-errors") # Required to test HTTPS

Capybara.register_driver :chrome do |app|
  Capybara::Selenium::Driver.new(app, browser: :chrome, options: chrome_options)
end

This configuration will not work in conjunction with --headless, which causes chrome to fetch its configuration from another source and silently ignore command line parameters. For details, see: https://groups.google.com/a/chromium.org/forum/#!topic/headless-dev/eiudRsYdc3A

Make sure that RSpec resets the server after each test, and stops the server when the suite is finished (spec/support/mini_proxy.rb):

require "miniproxy"

RSpec.configure do |config|
  config.before :each, type: :feature do
    MiniProxy.reset
  end

  config.after :each, type: :feature do
    # Ignore any requests made between specs
    MiniProxy.ignore_all_requests
  end

  config.after :suite do
    MiniProxy.stop
  end
end

In your specs, to stub a request:

MiniProxy.stub_request(method: "POST", url: /example.com/, response: {
  headers: { "Foo" => "bar" },
  code: 200,
  body: "hello",
})

The default behaviour is to block the request, display a warning and return an empty 200 response.

To allow unstubbed requests to hit external servers, you can use a driver configured without using MiniProxy as a proxy server. However, this is not recommended as you will almost certainly have unreliable tests.

Allowed Hosts

MiniProxy allows requests from the 127.0.0.1 and localhost by default.

If your test suite runs at a different address, you can configure a custom host using the MiniProxy.host option. Example:

MiniProxy.host = "95.124.236.242"

With this configuration, MiniProxy will allow all requests coming from the configured host.

You also can permit specific requests to pass through the proxy:

MiniProxy.allow_request(method: "GET", url: /example.com/)

This implicitly allows CONNECT requests for 'example.com' to permit HTTPS.

Developing

Pull requests are welcome, we try our best to stick with semver, avoid breaking changes to the API whenever possible.

Run the unit tests:

bundle exec rspec spec/lib

Integration tests use capybara/selenium/firefox. So you'll need a modern version of Firefox and Geckodriver on your system PATH. They can be run like so:

bundle exec rspec spec/integration

Alternatively you can just rely on CI to run the integration tests.

And of course, to run all the tests:

bundle exec rspec

Alternatives

• Puffing Billy - MiniProxy's more capable and more complex cousin
• EvilProxy - Lighter weight than Puffing Billy, with a focus on HTTPS MITM support