diff --git a/guides/links.yaml b/guides/links.yaml
new file mode 100644
index 0000000..d1b7ca5
--- /dev/null
+++ b/guides/links.yaml
@@ -0,0 +1,2 @@
+mocking:
+  order: 5
diff --git a/guides/mocking/readme.md b/guides/mocking/readme.md
new file mode 100644
index 0000000..124d271
--- /dev/null
+++ b/guides/mocking/readme.md
@@ -0,0 +1,75 @@
+# Mocking
+
+This guide explains how to modify `Async::HTTP::Client` for mocking responses in tests.
+
+## Mocking HTTP Responses
+
+The mocking feature of `Async::HTTP` uses a real server running in a separate task, and routes all requests to it. This allows you to intercept requests and return custom responses, but still use the real HTTP client.
+
+In order to enable this feature, you must create an instance of {ruby Async::HTTP::Mock::Endpoint} which will handle the requests.
+
+~~~ ruby
+require 'async/http'
+require 'async/http/mock'
+
+mock_endpoint = Async::HTTP::Mock::Endpoint.new
+
+Sync do
+	# Start a background server:
+	server_task = Async(transient: true) do
+		mock_endpoint.run do |request|
+			# Respond to the request:
+			::Protocol::HTTP::Response[200, {}, ["Hello, World"]]
+		end
+	end
+	
+	endpoint = Async::HTTP::Endpoint.parse("https://www.google.com")
+	mocked_endpoint = mock_endpoint.wrap(endpoint)
+	client = Async::HTTP::Client.new(mocked_endpoint)
+	
+	response = client.get("/")
+	puts response.read
+	# => "Hello, World"
+end
+~~~
+
+## Transparent Mocking
+
+Using your test framework's mocking capabilities, you can easily replace the `Async::HTTP::Client#new` with a method that returns a client with a mocked endpoint.
+
+### Sus Integration
+
+~~~ ruby
+require 'async/http'
+require 'async/http/mock'
+require 'sus/fixtures/async/reactor_context'
+
+include Sus::Fixtures::Async::ReactorContext
+
+let(:mock_endpoint) {Async::HTTP::Mock::Endpoint.new}
+
+def before
+	super
+	
+	# Mock the HTTP client:
+	mock(Async::HTTP::Client) do |mock|
+		mock.wrap(:new) do |original, endpoint|
+			original.call(mock_endpoint.wrap(endpoint))
+		end
+	end
+	
+	# Run the mock server:
+	Async(transient: true) do
+		mock_endpoint.run do |request|
+			::Protocol::HTTP::Response[200, {}, ["Hello, World"]]
+		end
+	end
+end
+
+it "should perform a web request" do
+	client = Async::HTTP::Client.new(Async::HTTP::Endpoint.parse("https://www.google.com"))
+	response = client.get("/")
+	# The response is mocked:
+	expect(response.read).to be == "Hello, World"
+end
+~~~
diff --git a/lib/async/http.rb b/lib/async/http.rb
index 6b67b2b..3eac9b4 100644
--- a/lib/async/http.rb
+++ b/lib/async/http.rb
@@ -8,4 +8,6 @@
 require_relative 'http/client'
 require_relative 'http/server'
 
+require_relative 'http/internet'
+
 require_relative 'http/endpoint'
diff --git a/lib/async/http/mock.rb b/lib/async/http/mock.rb
new file mode 100644
index 0000000..050f1c2
--- /dev/null
+++ b/lib/async/http/mock.rb
@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+#
+# Copyright, 2019, by Samuel G. D. Williams. <http://www.codeotaku.com>
+# 
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+# 
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+# 
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+
+require_relative 'mock/endpoint'
diff --git a/lib/async/http/mock/endpoint.rb b/lib/async/http/mock/endpoint.rb
new file mode 100644
index 0000000..798caef
--- /dev/null
+++ b/lib/async/http/mock/endpoint.rb
@@ -0,0 +1,70 @@
+# frozen_string_literal: true
+#
+# Copyright, 2019, by Samuel G. D. Williams. <http://www.codeotaku.com>
+# 
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+# 
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+# 
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+
+require_relative '../protocol'
+
+require 'async/queue'
+
+module Async
+	module HTTP
+		module Mock
+			# This is an endpoint which bridges a client with a local server.
+			class Endpoint
+				def initialize(protocol = Protocol::HTTP2, scheme = "http", authority = "localhost", queue: Queue.new)
+					@protocol = protocol
+					@scheme = scheme
+					@authority = authority
+					
+					@queue = queue
+				end
+				
+				attr :protocol
+				attr :scheme
+				attr :authority
+				
+				# Processing incoming connections
+				# @yield [::HTTP::Protocol::Request] the requests as they come in.
+				def run(parent: Task.current, &block)
+					while peer = @queue.dequeue
+						server = @protocol.server(peer)
+						
+						parent.async do
+							server.each(&block)
+						end
+					end
+				end
+				
+				def connect
+					local, remote = ::Socket.pair(Socket::AF_UNIX, Socket::SOCK_STREAM)
+					
+					@queue.enqueue(remote)
+					
+					return local
+				end
+				
+				def wrap(endpoint)
+					self.class.new(@protocol, endpoint.scheme, endpoint.authority, queue: @queue)
+				end
+			end
+		end
+	end
+end
diff --git a/test/async/http/mock.rb b/test/async/http/mock.rb
new file mode 100644
index 0000000..d54840c
--- /dev/null
+++ b/test/async/http/mock.rb
@@ -0,0 +1,74 @@
+# Copyright, 2019, by Samuel G. D. Williams. <http://www.codeotaku.com>
+# 
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+# 
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+# 
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+
+require 'async/http/mock'
+require 'async/http/endpoint'
+require 'async/http/client'
+
+require 'sus/fixtures/async/reactor_context'
+
+describe Async::HTTP::Mock do
+	include Sus::Fixtures::Async::ReactorContext
+	
+	let(:endpoint) {Async::HTTP::Mock::Endpoint.new}
+	
+	it "can respond to requests" do
+		server = Async do
+			endpoint.run do |request|
+				::Protocol::HTTP::Response[200, [], ["Hello World"]]
+			end
+		end
+		
+		client = Async::HTTP::Client.new(endpoint)
+		
+		response = client.get("/index")
+		
+		expect(response).to be(:success?)
+		expect(response.read).to be == "Hello World"
+	end
+	
+	with 'mocked client' do
+		it "can mock a client" do
+			server = Async do
+				endpoint.run do |request|
+					::Protocol::HTTP::Response[200, [], ["Authority: #{request.authority}"]]
+				end
+			end
+			
+			mock(Async::HTTP::Client) do |mock|
+				replacement_endpoint = self.endpoint
+				
+				mock.wrap(:new) do |original, original_endpoint, **options|
+					original.call(replacement_endpoint.wrap(original_endpoint), **options)
+				end
+			end
+			
+			google_endpoint = Async::HTTP::Endpoint.parse("https://www.google.com")
+			client = Async::HTTP::Client.new(google_endpoint)
+			
+			response = client.get("/search?q=hello")
+			
+			expect(response).to be(:success?)
+			expect(response.read).to be == "Authority: www.google.com"
+		ensure
+			response&.close
+		end
+	end
+end