How GOV.UK uses contract testing

1. GOV.UK Tech Monthly - Publishing 2.0 team
29th May 2015
David Heath
Developer
@dgheath21

2. GOV.UK
Content
Schemas
GOV.UKDavid Heath

3. @bradwright - GOV.UKGOV.UK
What’s it for?
David Heath

4. @bradwright - GOV.UKGOV.UK
What’s it for?
- confidence
David Heath

5. @bradwright - GOV.UKGOV.UK
What’s it for?
- confidence
- go faster
David Heath

6. @bradwright - GOV.UKGOV.UK
Publishing pipeline
overview
David Heath

7. @bradwright - GOV.UKGOV.UKDavid Heath
Publishing
app
Content
store
Frontend
JSON JSON
{
“base_path”: ...,
…
}
{
“base_path”: ...,
…
}

8. @bradwright - GOV.UKGOV.UKDavid Heath
Publishing
app
Content
store
Frontend
JSON JSON
{
“base_path”: ...,
…
}
{
“base_path”: ...,
…
}Transformation

9. @bradwright - GOV.UKGOV.UKDavid Heath
Metadata
Details
Links
Content item
{
base_path:
format:
public_updated_at:
details: {
...
},
links: {
…
}
}

10. @bradwright - GOV.UKGOV.UKDavid Heath
Publisher
"required": [
"publishing_app",
"rendering_app",
"update_type",
"format",
"locale",
"public_updated_at"
],
Frontend
"required": [
"base_path",
"format",
"locale",
"public_updated_at"
],
Metadata changes

11. @bradwright - GOV.UKGOV.UKDavid Heath
Publisher Frontend
content_id currently optional (maybe
required in future)
Absent
routes Routes (must be within
base_path)
Absent
redirects Only for format==’redirect’ Absent

12. @bradwright - GOV.UKGOV.UKDavid Heath
Links expansion (publisher)
“links”: {
“lead_organisations”: [
“ab517cc2-80df-48f2-8325-1b8af95b8f71”
]
}

13. Links expansion (frontend)
“links”: {
“lead_organisations”: [
{
"title": "Department for International Development",
"base_path": "/government/organisations/dfid",
"api_url": "https://www.gov.uk/api/organisations/dfid",
"web_url": "https://www.gov.uk/government/organisations/dfid",
"locale": "en"
}
]
}
@bradwright - GOV.UKGOV.UKDavid Heath

14. Details hash
stays the same :-)
@bradwright - GOV.UKGOV.UKDavid Heath

15. Content item transformation
{
base_path:
format:
public_updated_at:
details: {
...
},
links: {
…
}
}
@bradwright - GOV.UKGOV.UKDavid Heath
Metadata (fields change)
Details (stays same)
Links (expanded)

16. @bradwright - GOV.UKGOV.UK
How can we test this?
David Heath

17. @bradwright - GOV.UKGOV.UKDavid Heath
Publishing
app
Content
store
Frontend

18. @bradwright - GOV.UKGOV.UKDavid Heath
Publishing
app
Frontend
Content
store

19. @bradwright - GOV.UKGOV.UKDavid Heath
Publishing
app
Frontend
Test that this
produces the
right output
Test that this works
with a variety of valid
inputs

20. @bradwright - GOV.UKGOV.UKDavid Heath
Publishing
app
Frontend
Schema

21. Examples
@bradwright - GOV.UKGOV.UKDavid Heath
Publishing
app
Frontend
Schema

22. Examples
@bradwright - GOV.UKGOV.UKDavid Heath
Publishing
app
Frontend
Schema
Match?

23. Examples
@bradwright - GOV.UKGOV.UKDavid Heath
Publishing
app
Frontend
Schema
Match?
GOV.UK Content Schemas

24. @bradwright - GOV.UKGOV.UKDavid Heath
govuk-content-schemas

25. @bradwright - GOV.UKGOV.UKDavid Heath

26. @bradwright - GOV.UKGOV.UKDavid Heath
details.json
metadata.json
links.json
publisher/
schema.json
frontend/
schema.json
curated
examples
curated
examples
combine_publisher_schema
generate_frontend_schema
validate;
ensure_example_base_paths_unique
validated
examples
Build process (Makefile)

27. Examples
@bradwright - GOV.UKGOV.UKDavid Heath
Publishing
app
Frontend
Schema
Match?
GOV.UK Content Schemas

28. @bradwright - GOV.UKGOV.UKDavid Heath
Publisher test
jenkins-schema.sh
# Clone govuk-content-schemas dependency for contract tests
rm -rf tmp/govuk-content-schemas
git clone git@github.com:alphagov/govuk-content-schemas.git
tmp/govuk-content-schemas
cd tmp/govuk-content-schemas
git checkout $SCHEMA_GIT_COMMIT
cd ../..
# Run tests
time bundle install --path "${HOME}/bundles/${JOB_NAME}" --deployment
RAILS_ENV=test GOVUK_CONTENT_SCHEMAS_PATH=tmp/govuk-content-schemas time bundle
exec rake test:publishing_schemas --trace

29. @bradwright - GOV.UKGOV.UKDavid Heath
Publisher test
test_publishing_schemas.rake
namespace :test do
Rake::TestTask.new(:publishing_schemas => "test:prepare") do |t|
t.libs << 'test'
t.test_files = FileList['test/unit/presenters/publishing_api_presenters/*_test.rb']
end
Rake::Task['test:publishing_schemas'].comment =
"Test publishing API presenters against external schemas"
end

30. @bradwright - GOV.UKGOV.UKDavid Heath
Publisher test
test/unit/presenters/publishing_api_presenters/case_study_test.rb
test "links hash includes world locations" do
location = create(:world_location)
case_study = create(:published_case_study,
world_locations: [location])
presented_hash = present(case_study)
assert_valid_against_schema(presented_hash, 'case_study')
assert_equal [location.content_id], presented_hash[:links][:world_locations]
end

31. @bradwright - GOV.UKGOV.UKDavid Heath
Publisher test
- use govuk-content-schema-test-helpers
- define jenkins-schema.sh
- contract tests should ideally be stand-
alone (separate test file)

32. Examples
@bradwright - GOV.UKGOV.UKDavid Heath
Publishing
app
Frontend
Schema
Match?
GOV.UK Content Schemas

33. Frontend test
test/contracts/govuk_content_schemas_test.sh
class GovukContentSchemasTest < ActionDispatch::IntegrationTest
include GovukContentSchemaExamples
all_examples_for_supported_formats.each do |content_item|
test "can successfully render #{content_item['base_path']} schema example" do
content_store_has_item(content_item['base_path'], content_item)
get content_item['base_path'].sub(/^//, '')
assert_response :success
end
end
end
@bradwright - GOV.UKGOV.UKDavid Heath

34. Adding a field to a format
1. Branch govuk-content-schemas
2. Add optional field
3. Push branch, all contract tests run
4. Merge!
@bradwright - GOV.UKGOV.UKDavid Heath

35. @bradwright - GOV.UKGOV.UKDavid Heath

36. Adding a new format
1. Branch govuk-content-schemas
2. Add schema and examples
3. Make sure publisher and frontend
tests set up
4. Push branch
@bradwright - GOV.UKGOV.UKDavid Heath

37. Dummy content store
@bradwright - GOV.UKGOV.UKDavid Heath

38. @bradwright - GOV.UKGOV.UK
Summing up
David Heath

39. @bradwright - GOV.UK
Your
safety
net

40. @bradwright - GOV.UK
confidence
publisher
frontend

41. Links
● https://github.com/alphagov/govuk-content-schemas
● https://github.com/alphagov/govuk-content-schema-test-helpers
● https://github.com/alphagov/govuk-dummy_content_store
@bradwright - GOV.UKGOV.UKDavid Heath

42. GOV.UK Tech Monthly - Publishing 2.0 team
29th May 2015
David Heath
Developer
@dgheath21