Testing microservices with consumer-driven …...•Introducing microservices testing challenges •...

Testing Java Microservices with Consumer-driven contracts

Andrew Morgan @mogronalol

Microservices testing is hard

Consumer driven contract testing

Andrew Morgan @mogronalol

• Independent Consultant specialising in microservices & continuous delivery

• PluralSight Author • InfoQ Editor

About Me

• Introducing microservices testing challenges

• Consumer-driven contract testing overview

• Following through the workflow with Spring Cloud Contract

• Advanced consumer-driven contract concepts

Agenda

Payments

Accounts

Loans

What are Microservices?

Rewards

HTTP

HTTP

Payments

Accounts

Loans


Rewards

MessagingHTTP

HTTP

Payments

Accounts

Loans


Rewards

The root cause of testing challenges

Payments

REST API

Booking

End-to-end Testing Microservices

Automated tests Browser or other UI Environment

Build time

Debuggability

Infrastructure cost

Operations

Flakiness

Distributed monolith

Disadvantages of End-to-end Testing

Automated tests Microservice Mock or Stub of Dependency

Mocking or Stubbing Dependencies

False positives

Staleness

Difficult to maintain

Disadvantages of Mocking or Stubbing

The Weak Feedback Loop

Run individual microservice

testsBuild and deploy

to stage End-to-end test

False positives

Release

Slow and flaky





Agenda

What is Consumer-driven Contract Testing?

Fills the microservices testing gap

Continuous testing against contracts

Consumers drive the implementation of providers

Independently testable and releasable microservices

???

Test Architecture Overview

Consumer Provider

Key Contract Characteristics

An agreed interaction between microservices

Continuously tested

No specific protocol

Not the same stubbing!

Definitely not API documentation!

What is an Interaction?

Scenario:

Should return no flights between London and Paris


Scenario:


Required Request:

GET /flights?from=London&to=Paris


Scenario:


Required Request:

GET /flights?from=London&to=Paris

Given Response:

200 []

The Consumer Side

Automated tests

Consuming Microservice

Stub of provider microservice

Generates

The interaction our test depends on

The Provider Side

Pre-defined contract

Providing Microservice

Contract verification tests

Generates

Fast and reliable feedback

Less money spent on infrastructure

API delivers exactly what is required

Understanding dependency hell

No stale stubs

Easy to work in parallel

The Benefits





Agenda

Spring Cloud Contract Overview

JVM-based CDC framework

Spring Boot Integration

Groovy Based Contract Definition Language

Message-driven and HTTP-driven interactions

Credit Card Application Feature


JUnit Test Credit card applications service

Credit score service




Applies for credit card




Calculates credit score




Accepts or rejects based on credit score

Following the CDC Workflow

Write a failing test

Define Contract

Build stubs

Make tests pass

Build verification

tests

Make tests pass

A Failing Test

Implementing Our Endpoint

JUnit Test



Does not exist





Fails here



Define Contract

Contract Definition Language

Request made by our test

Response expected by our test



Define Contract

Build stubs

Stub Generation

Contract Spring Cloud Contract Plugin

Stub Jar

wiremock.org

http://wiremock.org



Define Contract

Build stubs

Make tests pass

The Stub Runner

Download given stubs

Boots WireMock

Imports stubs into Wiremock

From a Failing Test

Unit test Credit card applications service


Fails here

…to a Passing Test

Unit test Credit card applications service

Spring Cloud Contract Stub

Passes here



Define Contract

Build stubs

Make tests pass

Build verification

tests

Provider Test Generation

Contract Spring Cloud Contract Plugin

Verification Tests



Define Contract

Build stubs

Make tests pass

Build verification

tests

Make tests pass

From Failing…

Contract Verification Tests


To Passing…

Contract Verification Tests


Implement me

- Marcin Grzejszczak

“Consumer-driven contracts are like TDD applied at the API level.”





Agenda

Does this only work with exact comparisons?

Regex

JSON

XML

XPath

Subsets

Starts with

Ignore casing

More

What about messaging?

Message-driven CDC

Consumer Provider

Message-driven CDC

Consumer ProviderBroker

Why Messaging?

Message schemas and queues are shared

Asynchronous failures are a debugging nightmare!

Brokers are slow

Where do we store our contracts?

Contract Repository

Talk Summary

Don’t build and test microservices like a monolith

Consumer-driven contracts promote independence

Leverage frameworks like Spring Cloud Contract and

Pact

https://www.pluralsight.com/profile/author/andrew-morgan

Questions?

@mogronalol

Testing microservices with consumer-driven …...•Introducing microservices testing challenges •...

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