# Testing
> 43 posts about Testing, summarised, each linking to the original.

## Articles

### [This Rocket Ain't Stopping - Achieving Zero Downtime for Rails to Golang API Migration](https://yomu.fyi/post/this-rocket-ain-t-stopping-achieving-zero-downtime-for-rails-to-golang.md)
- Company: [Grab](https://yomu.fyi/company/grab.md)
- Author: Lian Yuanlin
- Published: Oct 18, 2016

Grab transitioned its public passenger app APIs from a legacy Rails application to a Golang service-oriented architecture to consolidate its codebase and engineering teams. Initial attempts to proxy traffic through a cloned Rails server via gRPC were abandoned after encountering TCP load imbalances during autoscaling events and memory leaks in the gRPC Ruby gem. The team pivoted to direct logic migration, porting Ruby logic directly into Go while decomposing modules into standalone services. Verification relied on log-based load testing and live shadow testing, where write operations were safely validated using mock data access layers that evaluated expected database outcomes. Production rollout progressed endpoint-by-endpoint using requests-per-second traffic throttling and prewarmed AWS Elastic Load Balancers before executing the final DNS switch.


### [Grab Vietnam Careers Week](https://yomu.fyi/post/grab-vietnam-careers-week.md)
- Company: [Grab](https://yomu.fyi/company/grab.md)
- Author: Grab Engineering
- Published: Oct 14, 2016

Grab announced its first Grab Vietnam Careers Week, held in Ho Chi Minh City from 22 to 26 October 2016, aimed at hiring engineers to improve regional transportation and reduce congestion. At the time, Grab operated on 23 million mobile devices supported by 460,000 drivers across Southeast Asia. The announcement features an interview with Singapore-based iOS engineer Hai Pham and Android engineer Son Nguyen discussing team culture, regular hackathons termed "Grabathons", and relocation to Singapore. Technical candidates undergo a Codility test and are evaluated on clean mobile architecture, testing, and performance maintenance. The engineers also offer advice on apartment hunting through online community forums and adapting to life in Singapore.


### [Why Test the Design with Only 5 Users](https://yomu.fyi/post/why-test-the-design-with-only-5-users.md)
- Company: [Grab](https://yomu.fyi/company/grab.md)
- Author: Avinash Papatla
- Published: Aug 26, 2016

Stakeholders often question whether qualitative testing with only five participants yields reliable design findings. The chosen research problem dictates the methodology, with qualitative usability evaluations requiring smaller cohorts than broad quantitative surveys. Jakob Nielsen's 1993 analysis demonstrated that testing with five participants uncovers 75 to 80 percent of usability issues, after which additional users yield diminishing returns. In agile environments, teams maximize efficiency by iterating designs across successive rounds of five participants rather than testing large cohorts simultaneously. This five-user threshold applies strictly to qualitative usability testing for specific feature flows rather than opinion gathering, A/B testing, or multi-segment user analysis.


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