The document discusses the approach to re-engineering legacy applications using micro-service architecture, emphasizing the development of independently deployable services. It highlights the complexities of testing within this framework, including the importance of comprehensive testing strategies and understanding upstream and downstream dependencies. The document also addresses challenges in maintaining effective testing practices amid evolving business processes.

1. #ATAGTR2017
16th 17th March
Test Approach for Re-engineering Legacy
Applications based on Micro-service
Architecture
Sandhya Sasidharan
ThoughtWorks Technologies

2. WHAT IS A MICRO-SERVICE BASED ARCHITECTURE?
▫ A method of developing software applications as a suite of
independently deployable, small, modular services in which each service
runs a unique process and communicates through a well-defined,
lightweight mechanism to serve a business goal

3. WITH EASE COMES OVERHEAD AS WELL
One Business Feature
-Multiple services

4. WITH EASE COMES OVERHEAD AS WELL
Testing becomes Complex and Cumbersome

5. 5
Case Study

6. UNDERSTANDING THE INTEGRATION POINTS
6
‣ Identify direct upstream & downstream dependencies
‣ Understand the business domain and business processes
‣ Build safety net for the legacy / existing parts
‣ Understand the roadmap of the evolution

7. PLAN YOUR TESTS
7
End to End Tests
‣ Create contract level / service level tests
‣ Use stubs/mocks
‣ Provides faster feedback to development
team
‣ Provides early safety net
‣ Minimises co-ordination constraints with
other teams
‣ Separates ownership
‣ Based on assumptions and agreements
Lower level tests
‣ Trigger a business action from an
upstream system
‣ See the data/information being
consumed
‣ Provides more confidence to
stakeholders
‣ Requires heavy co-ordination with
other teams
‣ Creates constraints
‣ Slower

8. CONTRACTS
Provider
Consumer1 Consumer2
Column Data type
Id Int
Name Varchar
Category Double
(not Nullable)
Price Float
Column Data type
Id Int
Name Varchar
Category Double
(not Nullable)
Column Data type
Id Int
Price Float

9. TEMPLATE VERIFICATION
9
[
{
"article_unit": string,
"category": {
"id": integer,
"name": string
},
"sub_category": {
"id": integer,
"name": string
},
"article_weight": integer,
"name": string,
"id": integer,
“frozen”: boolean
}
]
End Point Provides
[
{
"category": {
"id": integer,
"name": string
},
"sub_category": {
"id": integer,
"name": string
},
"name": string,
"id": integer,
“frozen”: boolean
}
]
Consumer Requires

10. RESPONSE VERIFICATION
10
[
{
"article_unit": "C",
"category": {
"id": 1,
"name": "SALMON"
},
"article_weight": 500,
“brand_name": "SALMON",
"id": 123,
“frozen”: true
}
]
- request:
url: /articles/123.json
method: GET
file: articles/GET_articleId.json
- request:
url: /articles/456.json
method: GET
file: articles/GET_articleId.json
[
{
"article_unit": "X",
"category": {
"id": 456,
"name": "CHOCOLATE"
},
“article_weight": ,
“brand_name": "CADBURY",
"id": 456,
“frozen”: false
}
]

11. 11
Template verification
Response
Verifications
E2E

12. 12
Huge Data

13. 13
‣ Understand the data model and representations
‣ Identify the Quantum of variations
‣ Understand the boundary of the systems
‣ Apply the Pareto principle (80-20 rule)
UNDERSTANDING DATA

14. APPROACHES TO SETUP TEST DATA
14
Database Dump Base Seed Data
&
Modify as needed
Setup data
for each test
Using existing services

15. 15

16. 16

17. SCALABLE TEST MODEL
17
‣ Model the tests and test data in such a way that re-work is minimised
• Using object-oriented techniques
• Understanding and representing the domain well
‣ Separate tests into tiers based on complexity and feedback cycle
‣ Use continuous integration techniques
‣ Fail fast and loud on dependency changes

18. 18
SAMPLE PIPELINE

19. SOME TESTING CHALLENGES
19
‣ Keeping up with the evolution of the dependent business processes
‣ Enthusiastic development team adding more E2E tests slowing the feedback cycle
‣ Frequent re-balancing of the tests
‣ Maintaining test data sanity

20. Agile Testing Alliance Global Testing Retreat 2017
THANK YOU
Reference for Implementation
https://martinfowler.com/articles/consumerDrivenContracts.html