HTTP Fake is a companion to the HTTP gem when you want a convenient way to test HTTP requests by swapping out your real HTTP client with this fake HTTP client. Using a fake allows you to improve the performance of your test suite by answering fake responses without hitting a live API. You’ll still want to test against a live API, eventually, within your integration tests but at a lower level, like your unit tests, you can use this gem instead. This gem is particularly useful when using Dependency Injection, especially when coupled with the Infusible gem.
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Provides a fake HTTP client as a testing companion to the HTTP gem.
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Supports the following HTTP verbs: CONNECT, DELETE, GET, HEAD, OPTIONS, PATCH, POST, PURGE, PUT, and TRACE.
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Uses a simple DSL for defining HTTP endpoints, headers, bodies, and statuses.
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Works well with objects that use Dependency Injection.
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Speeds up your test suite when you don’t need a live API.
To install within an existing project, run:
bundle add http-fakeYou’ll want to ensure this gem is part of your test group since it’s only meant to aid in writing specs.
This gem works with any test framework. For demonstration purposes, we’ll assume you’re using RSpec but you can adapt these examples to your test framework of choice. A simple spec might look like this:
RSpec.describe Endpoint do
subject(:endpoint) { described_class.new http: }
let :http do
HTTP::Fake::Client.new do
get "/customers" do
headers["Content-Type"] = "application/json"
status 200
<<~JSON
{
"customers": [
{"name": "Jill Smith"}
]
}
JSON
end
end
end
describe "#customers" do
it "answers customers array when successful" do
response = endpoint.customers
expect(response.parse).to eq(customers: [{name: "Jill Smith"}])
end
end
endAs you can see, our fake http client has been defined and injected into our endpoint subject. When the fake is defined, the path, headers, status, and body are registered as well. This allows the fake to match against your real implementation’s URL path and swap out acquiring a real HTTP response with fake response instead. When asking the endpoint for its customers, we get back the fake response with all of the normal capabilities of the real HTTP client. This works because this gem uses Mustermann for pattern matching against the routes you define and also means you can define routes that are explicit — as shown above — or fuzzy based on your testing needs.
Here’s an example where multiple endpoints are defined for the same fake in case your implementation needs to test multiple endpoints at once:
let :http do
HTTP::Fake::Client.new do
connect("/") { status 200 }
head("/") { status 200 }
options("/") { status 204 }
get "/customers" do
headers["Content-Type"] = "application/json"
status 200
<<~JSON
{
"customers": [
{"name": "Jill Smith"}
]
}
JSON
end
post "/customers" do
headers["Content-Type"] = "application/json"
status 201
{}
end
put "/customers/1" do
headers["Content-Type"] = "application/json"
status 200
end
patch "/customers/1" do
headers["Content-Type"] = "application/json"
status 200
end
delete("/customers/1") { status 204 }
trace("/") { status 200 }
end
endSo far you’ve only seen usage of JSON responses but you might want to use other MIME types. For example, XML:
HTTP::Fake::Client.new do
get "/customers/1" do
headers["Content-Type"] = "application/xml"
status 200
<<~XML
<customer>
<id>1</id>
<name>Jill Smith</name>
</customer>
XML
end
endPlain text would work too:
HTTP::Fake::Client.new do
get "/customers" do
headers["Content-Type"] = "text/plain"
status 200
"1 - Jill Smith"
"2 - Tom Bombadill"
end
endYou might even want to import a fixture which is especially handy when the response is verbose or needs to be reused in different ways. Example:
# Single
HTTP::Fake::Client.new do
get "/customers/1" do
headers["Content-Type"] = "application/json"
status 200
SPEC_ROOT.join("support/fixtures/customer.json").read
end
end
# Multiple
HTTP::Fake::Client.new do
get "/customers" do
headers["Content-Type"] = "application/json"
status 200
<<~JSON
[#{SPEC_ROOT.join("support/fixtures/customer.json").read}]
JSON
end
endSince you have the ability to define your own headers and status codes, you can also test failure response behavior as well. I’ll leave that up to you to explore and experiment with further.
To contribute, run:
git clone https://github.com/bkuhlmann/http-fake
cd http-fake
bin/setupYou can also use the IRB console for direct access to all objects:
bin/console-
Built with Gemsmith.
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Engineered by Brooke Kuhlmann.
