[TestWarez 2017] Behavior Driven Development in a complex environment - Consumer Driven Contracts

Consumer Driven
Contracts
Remigiusz Dudek
Software Quality Engineer

Questions
• What problem we’re trying to solve?
• How the problem were solved so far?
• How we want to solve it with CDC?
• What other problems do we introduce?

End-to-end
testing in a
highly
distributed
environment

Deploy all services in
one environment
Automated or
Manual
Production
similarity
Environment
stability
Test analysis
Feedback loop
Environment as
bottleneck
Proper versions
Test isolation
Environment
Maintenance
Manual
Cost (low only in
small scales at
the beginning)

Deploy single service
with mocks
Production
similarity
Environment
Stability
Test analysis
Feedback loop
Environment as
bottleneck
Proper versions
Test isolation
Environment
maintenance
Cost

Testing in
general
https://martinfowler.com/articles/microservice-testing/

Testing in
general
Consumer

Testing in
general
Client
Producer

How to do it with CDC ?
• Prove that mocks are alike production
• If collaborator behaviour changes all parties should be informed
immediately
• Generate all the boilerplate code

tests
proving
contract
conformance
Stub
Boilerplate
Client
(Consumer)
Server
(Producer)

How?
1. Define problem
2. Define contract
3. Generate STUBs for Client (Consumer)
4. Use STUBs forClient’s tests
5. Generate tests for Server (Producer)

1. Define problem & prepare project
• https://start.spring.io/
• WEB
• Cloud ContractVerifier
• Cloud Contract Stub Runner
Trip Advisor
Hotel Advisor
Car rental
Advisor
Ticket
booking
Advisor

1. Contract dependencies
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-contract-spec</artifactId>
</dependency>
<plugin>
<artifactId>spring-cloud-contract-maven-plugin</artifactId>
<version>1.1.1.RELEASE</version>
<extensions>true</extensions>
</plugin>

1. Contract description
Trip Advisor Hotel Advisor
GET /hotels?location=Krakow
{
"availableHotels": [
{
"id": "779",
"name": "Sheraton",
"address": "Kraków, ul. Jana Nowaka 1”
},
{
"id": "892",
"name": "Novotel",
"address": "Kraków, ul. Długa 5”
}
]
}

1. Contract
• Ignoring contract
• Passing value from file (starting from version
1.2.0)
• Executing method available in base class
• Creating response basing on data from requestContract.make {
ignored()
}
response {
status 200
body (execute("commandName(${fromRequest().body('some/string/path')})"))
headers {
contentType(applicationJson())
}
}

2. Generate STUBs
• Contract verifier plugin
• Generate and run tests
• Create and install STUBs
$> mvn clean install -DskipTests

3. Use STUBs for client tests
<dependencies>
<dependency>
<artifactId>spring-cloud-starter-contract-stub-runner</artifactId>
<scope>test</scope>
</dependency>
</dependencies>@AutoConfigureStubRunner(
ids = {"prv.dudekre:hotels-advisor:0.0.1-SNAPSHOT:stubs:6565"},
stubsPerConsumer = true,
consumerName = „tripAdvisor”,
workOffline = true)

<plugin>
<artifactId>spring-cloud-contract-maven-plugin</artifactId>
<version>1.1.1.RELEASE</version>
<extensions>true</extensions>
<configuration>
<contractDependency>
<groupId>prv.dudekre.cdc</groupId>
<artifactId>Hotel-advisor-contracts</artifactId>
<classifier>stubs</classifier>
<version>0.0.1-SNAPSHOT</version>
</contractDependency>
<contractsPath>META-INF/prv.dudekre.cdc/Hotel-advisor-contracts</contractsPath>
<contractsWorkOffline>true</contractsWorkOffline>
<baseClassMappings>
<baseClassMapping>
<contractPackageRegex>.*tripAdvisor.*</contractPackageRegex>
<baseClassFQN>prv.dudekre.cdc.contracts.HotelAdvisorBase</baseClassFQN>
</baseClassMapping>
</baseClassMappings>
</configuration>
</plugin>

$> mvn help:describe -Dplugin=org.springframework.cloud:spring-cloud-contract-maven-plugin
Name: Spring Cloud Contract Maven Plugin
Description: Spring Cloud Contract Maven Plugin
Group Id: org.springframework.cloud
Artifact Id: spring-cloud-contract-maven-plugin
Version: 1.1.2.RELEASE
Goal Prefix: spring-cloud-contract
This plugin has 5 goals:
spring-cloud-contract:convert
Convert Spring Cloud Contract Verifier contracts into WireMock stubs mappings.
This goal allows you to generate `stubs-jar` or execute
`spring-cloud-contract:run` with generated WireMock mappings.
spring-cloud-contract:generateStubs
Picks the converted .json files and creates a jar. Requires convert to be
executed first
spring-cloud-contract:generateTests
From the provided directory with contracts generates the acceptance tests on
the producer side
spring-cloud-contract:help
Display help information on spring-cloud-contract-maven-plugin.
Call mvn spring-cloud-contract:help -Ddetail=true -Dgoal=<goal-name> to
display parameter details.
spring-cloud-contract:run

@RunWith(SpringRunner.class)
@ContextConfiguration(classes = {ContractTestConfiguration.class})
public abstract class HotelsBase {
@Autowired HotelAdvisorService hotelAdvisorService;
@Before
public void setup() {
RestAssuredMockMvc.standaloneSetup(
new HotelAdvisorController(hotelAdvisorService));
}
}

APIVersioning
• Semantic versioning
• Keep contracts for each version of API
• Consider maven classifiers to mark production/dev versions (mind that it
doesn’t match the original idea behind classifier concept)
• Keep contracts in separate module/repository (different release cycle)

Defer breaking change
• Tolerant reader pattern
• Expand and contract pattern (3 steps to unbreake API change)
• 6 steps to unbreak DB schema change in continous deployment
environment (if you’re not doing continuous deployment you can simplify
the algorithm and have only 5 steps)

Expand and
Contract
From Sam Newman’s book „Building Microservices”

5 steps algorithm
• 0. Service (v1.0) using old data
structure
• 1. Add new data structure (1st
DB change) incompatible with
the old one (omitt constrainsts)

5 steps algorithm
• 2. Deploy new version (v1.1) of
your service reading from old
structure and writing to old and
new

5 steps algorithm
• 3. Migrate all old data to new
structure (2nd DB change) and
add constraints to new data
structure

5 steps algorithm
• 4. Release new version of your
service (v1.2) reading from new
and writing to new data
structure

5 steps algorithm
• 4. Clean old data structures (3rd
DB change)
2 service releases
3 DB changes

6 steps algorithm
• 0. Service (v1.0) using old data
structure
• 1. Deploy new version of your
service (v1.1) marking record
that it created/updated (not
needed if not doing continuous
deployment)

6 steps algorithm
• 2. Add new data structure (1st
DB schema change)
incompatible with the old one
(omitt constrainsts)

6 steps algorithm
• 3. Deploy new version of your service
(1.2) with quite complex (simple if not
doing continuous deployment) data
creation/updating logic:
• Create new data in old and new
structure
• If old data is not marked and new data
does not exist, read from old and write
to old and new
• If old data is not marked and new data
exists, read from new and write to old
and new
• If old data is marked, read from old and
write to old and new and remove marker

6 steps algorithm
• 4. Migrate old data in case when
new data does not exist or old
data is marked and add
constraints to new data
structure

6 steps algorithm
• 5. Deploy new version (1.3) of
your service reading from new
and writing to new data
structure

6 steps algorithm
• 6. Remove old data structure

CDC Advanced
• State-based behaviour (http://wiremock.org/docs/stateful-behaviour/)

[TestWarez 2017] Behavior Driven Development in a complex environment - Consumer Driven Contracts

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