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Because Web API Testing Should Be Easy

Because Web API Testing Should Be Easy

Web APIs are often called REST APIs, which recently became a part of the everyday life of many Python developers. Sure, it can be a blast to build an API with frameworks like Django or Flask, but writing tests for it can be a tedious drag: asserting every single HTTP code, set of headers, JSON responses, error states… you know the drill. Despite all that you do, you still need to assure your API clients won’t be exposed to any unexpected surprises. At Apiary, we've developed an Open Source testing framework called Dredd, which has baked in first-class Python support. It does all the heavy lifting and boring stuff for you while allowing you to alter the test cases with arbitrary Python code. Let Judge Dredd do your API justice.

Honza Javorek

March 13, 2017

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  1. import urllib2 gh_url = 'https://api.github.com' req = urllib2.Request(gh_url) password_manager =

    urllib2.HTTPPasswordMgrWithDefaultRealm() password_manager.add_password(None, gh_url, 'user', 'pass') auth_manager = urllib2.HTTPBasicAuthHandler(password_manager) opener = urllib2.build_opener(auth_manager) urllib2.install_opener(opener) handler = urllib2.urlopen(req) print handler.getcode() print handler.headers.getheader('content-type') Do you like this interface?
  2. >>> r = requests.get('https://api.github.com/user', ... auth=('user', 'pass')) >>> r.status_code 200

    >>> r.headers['content-type'] 'application/json; charset=utf8' >>> r.encoding 'utf-8' >>> r.text '{"type":"User"...' >>> r.json() {'disk_usage': 368627, 'private_gists': 484, ...} Do you like this interface?
  3. def test_basic_building(): req = requests.Request() req.url = 'http://kennethreitz.org/' req.data =

    {'life': '42'} pr = req.prepare() assert pr.url == req.url assert pr.body == 'life=42'
  4. test > RED > implement > test > GREEN req

    = requests.Request() req.url = 'http://kennethreitz.org/' req.data = {'life': '42'} pr = req.prepare() assert pr.url == req.url assert pr.body == 'life=42'
  5. Feature: Status code Background: Given you expect HTTP status code

    "200" Scenario: Different real response status When real status code is "500" Then Gavel will set some error for "status code" And Request or Response is NOT valid Scenario: Response status code match When real status code is "200" Then Gavel will NOT set any errors for "status code" And Request or Response is valid Gherkin / Cucumber
  6. RDD

  7. # Requests The `requests` library allows you to perform HTTP

    requests from your Python code. ## Example ```python >>> r = requests.get('https://github.com') >>> r.status_code 200 ``` ## License MIT README.md
  8. Readme Driven Development • chance to think through the project

    first • docs are ready - no need to write them retroactively • your team can use the interface before it exists • easy to discuss the interface with everyone
  9. # Calendar API The API gives you various means to

    work with date and time. ## GET /now Provides you with current date and time. - Response 200 (application/json) ```json { "day": 29, "month": 2, "year": 2017, "hour": 11, "minute": 45, "second": 38 } ``` API.md
  10. language: "python" python: - "3.6" before_install: - "npm install -g

    dredd" script: - "dredd API.md http://localhost:8000" Continuous Integration
  11. Remember • think first, design first, docs first, test first

    • discuss the the interface design before implementing • use the interface before implementing (mocks, tests) • have your interface design as a single source of truth • test implementation against the design