FakeWeb

FakeWeb is a helper for faking web requests in Ruby. It works at a global level, without modifying code or writing extensive stubs.

Installation

gem install fakeweb

Note: the gem was previously available as FakeWeb (capital letters), but now all versions are simply registered as fakeweb. If you have any old FakeWeb gems lying around, remove them: gem uninstall FakeWeb

Help and discussion

RDocs for the current release are available at fakeweb.rubyforge.org.

There’s a mailing list for questions and discussion at groups.google.com/group/fakeweb-users.

The main source repository is github.com/chrisk/fakeweb.

Examples

Start by requiring FakeWeb:

require 'fakeweb'

Registering basic string responses

FakeWeb.register_uri(:get, "http://example.com/test1", :body => "Hello World!")

Net::HTTP.get(URI.parse("http://example.com/test1"))
=> "Hello World!"

Net::HTTP.get(URI.parse("http://example.com/test2"))
=> FakeWeb is bypassed and the response from a real request is returned

Registering erb template responses

@somebody = "Kevin"
FakeWeb.register_uri(:get, "http://example.com/test1", :body => "Hello <%= @somebody%>!")

Net::HTTP.get(URI.parse("http://example.com/test1"))
=> "Hello Kevin!"

You can also call register_uri with a regular expression, to match more than one URI.

FakeWeb.register_uri(:get, %r|http://example\.com/|, :body => "Hello World!")

Net::HTTP.get(URI.parse("http://example.com/test3"))
=> "Hello World!"

And the match captures could be used in erb template.

FakeWeb.register_uri(:get, %r|http://example\.com/users/(\d+)\.json|, :body => %Q|{"id":<%=$1%>, "username":"user<%=$!%>"}|)

Net::HTTP.get(URI.parse("http://example.com/users/3.json"))
=> '{"id":3, "username":"user3"}'

The :body’s value could be a path of a file which stores the body content.

/path/to/body/content.text.erb:
Lorem ipsum dolor sit amet for user <%= $1%>

FakeWeb.register_uri(:get, %r|http://example\.com/users/(\d+)\.json|, :body => "/path/to/body/content.text.erb")

Net::HTTP.get(URI.parse("http://example.com/users/3.json"))
=> "Lorem ipsum dolor sit amet for user 3"

Replaying a recorded response

page = `curl -is http://www.google.com/`
FakeWeb.register_uri(:get, "http://www.google.com/", :response => page)

Net::HTTP.get(URI.parse("http://www.google.com/"))
# => Full response, including headers

The :response’s value could also be a path of file which stores the entire response from the server. ERB template and regular expression matching capture are supported too.

Adding a custom status to the response

FakeWeb.register_uri(:get, "http://example.com/", :body => "Nothing to be found 'round here",
                                                  :status => ["404", "Not Found"])

Net::HTTP.start("example.com") do |req|
  response = req.get("/")
  response.code     # => "404"
  response.message  # => "Not Found"
  response.body     # => "Nothing to be found 'round here"
end

Responding to any HTTP method

FakeWeb.register_uri(:any, "http://example.com", :body => "response for any HTTP method")

If you use the :any symbol, the URI you specify will be completely stubbed out (regardless of the HTTP method of the request). This can be useful for RPC-style services, where the HTTP method isn’t significant. (Older versions of FakeWeb always behaved like this, and didn’t accept the first method argument above; this syntax is now deprecated.)

Rotating responses

You can optionally call FakeWeb.register_uri with an array of options hashes; these are used, in order, to respond to repeated requests. Once you run out of responses, further requests always receive the last response. (You can also send a response more than once before rotating, by specifying a :times option for that response.)

FakeWeb.register_uri(:delete, "http://example.com/posts/1",
                     [{:body => "Post 1 deleted.", :status => ["200", "OK"]},
                      {:body => "Post not found",  :status => ["404", "Not Found"]}])

Net::HTTP.start("example.com") do |req|
  req.delete("/posts/1").body  # => "Post 1 deleted"
  req.delete("/posts/1").body  # => "Post not found"
  req.delete("/posts/1").body  # => "Post not found"
end

Using HTTP basic authentication

You can fake requests that use basic authentication by adding userinfo strings to your URIs:

FakeWeb.register_uri(:get, "http://example.com/secret", :body => "Unauthorized", :status => ["401", "Unauthorized"])
FakeWeb.register_uri(:get, "http://user:[email protected]/secret", :body => "Authorized")

Net::HTTP.start("example.com") do |http|
  req = Net::HTTP::Get.new("/secret")
  http.request(req)  # => "Unauthorized"
  req.basic_auth("user", "pass")
  http.request(req)  # => "Authorized"
end

Clearing registered URIs

The FakeWeb registry is a singleton that lasts for the duration of your program, maintaining every fake response you register. If needed, you can clean out the registry and remove all registered URIs:

FakeWeb.clean_registry

Blocking all real requests

When you’re using FakeWeb to replace all of your requests, it’s useful to catch when requests are made for unregistered URIs (unlike the default behavior, which is to pass those requests through to Net::HTTP as usual).

FakeWeb.allow_net_connect = false
Net::HTTP.get(URI.parse("http://example.com/"))
=> raises FakeWeb::NetConnectNotAllowedError

FakeWeb.allow_net_connect = true
Net::HTTP.get(URI.parse("http://example.com/"))
=> FakeWeb is bypassed and the response from a real request is returned

This is handy when you want to make sure your tests are self-contained, or you want to catch the scenario when a URI is changed in implementation code without a corresponding test change.

Specifying HTTP response headers

When you register a response using the :body option, you’re only setting the body of the response. If you want to add headers to these responses, simply add the header as an option to register_uri:

FakeWeb.register_uri(:get, "http://example.com/hello.txt", :body => "Hello", :content_type => "text/plain")

This sets the “Content-Type” header in the response.

More info

FakeWeb lets you decouple your test environment from live services without modifying code or writing extensive stubs.

In addition to the conceptual advantage of having idempotent request behaviour, FakeWeb makes tests run faster than if they were made to remote (or even local) web servers. It also makes it possible to run tests without a network connection or in situations where the server is behind a firewall or has host-based access controls.

FakeWeb works with anything based on Net::HTTP–both higher-level wrappers, like OpenURI, as well as a ton of libraries for popular web services.

Known Issues

  • Request bodies are ignored, including PUT and POST parameters. If you need different responses for different request bodies, you need to request different URLs, and register different responses for each. (Query strings are fully supported, though.) We’re currently considering how the API should change to add support for request bodies in 1.3.0. Your input would be really helpful: see groups.google.com/group/fakeweb-users/browse_thread/thread/44d190a6b12e4273 for a discussion of some different options. Thanks!

Copyright 2006-2007 Blaine Cook

Copyright 2008-2009 various contributors

FakeWeb is free software; you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later
version.

FakeWeb is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
details.

You should have received a copy of the GNU General Public License along
with FakeWeb; if not, write to the Free Software Foundation, Inc., 51
Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

See LICENSE.txt for the full terms.