1.
Integration
Testing For
Polyglot
Ecosystems
DigitalOcean Berlin Meetup
@ Factory - 19.04.2016

2.
WHO AM I?
David Worth
Software Engineer

3.
SOFTWARE ENGINEER WANTED
HELP US BUILD OUR NEXT BIG THING!
Services
Clients
APIs

4.
MVP! YAY!

5.
PROFIT!

6.
DATA SCIENTIST WANTED!
HELP US UNDERSTAND OUR THING!
Models
Classifiers
APIs

7.
COMPLICATIONS
• Depending on your protocol responses are “unstructured” (e.g.
JSON) and changes to a client or API may break contracts.
• In Theory tests prevent this, but only if the tests and the tested
code stay in sync with one another.

8.
TESTING THEM TOGETHER

9.
GENERAL IDEA
• Write and test an API in one language using standard idioms of
the language
• Write and test a client in another language using standard idioms
of the language
• Test the client against a live instance of the API run in a
container - automatically
• Tear down all of the infrastructure
• Do it all FAST

10.
APIClient
API URL Exposed in the Environment
by RSpec or Drone
Run Manually or by CI Run Automatically
Exposed to Client Not Exposed

11.
DEMO!

12.
CAVEATS…

13.
WAIT FOR IT…
• While the act of starting the container is extremely fast,
application boot may take some time.
• Blindly sleep(2)for “long enough”
• Poll the application (a health endpoint) - with back-off?

14.
IT’S A TRAP!
SEEDING DATA
• These are pure integration tests - do not be tempted to feed data
into a persistence layer depended upon by the system under test.
Data there must “arrive” as if in production - and be cleaned up
manually.

15.
THERE ARE OTHER PATHS
• You could Docker Compose for each test (suite) run
• We basically reinvent it here
• Less API Support than raw Docker
• You could simply run your tests with Drone, locally or in CI, rather
than RSpec
• Drone is slower but potentially parallelization could solve this

16.
QUESTIONS?

17.
DANKE.