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Serguei Filimonov

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Combating false positive failures in CI

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Scope and the problem

If you experience a CI build turning red due to an intermittent failure, such as in a Capybara test, this post is for you.

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Roundup of Data and Immutability Resources

Data, Big and Small

As part of Pivotal, Labs associate more and more with the “Big Data” discussions, tools and methods. This is very exciting. Your applications serve users and deliver immediate value, and a whole world of past data is unlocked, providing deep insight into your business.

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Quick abstracts of YAML or JSON documents

When I work with unfamiliar YAML files specifying deployment manifests, product metadata, serialized records, etc. I want to quickly get a sense of a few things:

What is the set of keys in this data structure? If the structure(nested keys) of the document changed over time, what is the quick summary of changes structure_digest

Given the following long YAML file, I don’t really want to read through all of it to learn what keys and paths are available in it:

{ "receipt": "Oz-Ware Purchase Invoice", "date": "2012-08-06", "customer": { "given": "Dorothy", "family": "Gale" }, "items": [ { "part_no": "A4786", "descrip": "Water Bucket (Filled)", "price": 1.47, "quantity": 4 }, { "part_no": "E1628", "descrip": "High Heeled "Ruby" Slippers", "size": 8, "price": 100.27, }, …(many many more items ) ] }

Lets remove the value content, focus on structure, summarizing array entries as one:

>structure_digest order1.yml order2.yml ...

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Fact-based state in Rails

Maybe you learned this from experience or you joined a Rich Hickey-esque immutability craze, but one way or another you know state machines are complicated. They couple together a variety of meanings and easily grow out of control as your application gets more and more interesting.

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A Checklist for your Planning Meeting


What do construction, aviation, and internal medicine have in common? They all manage tremendous complexity that has in the last 100 years far surpassed the capacity of any individual to learn despite decades of education and training. Yet major building collapses are extremely rare, flying is the safest way to travel, and surgeons…well, they perform miracles.

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Capybara's save_page with CSS

At Pivotal, we often use Capybara to write a suite of integration tests that navigate a browser through any scenario that can emerge in the application. We use these tests to guard against regressions and to drive out the design of the application in a red-green cycle throughout the day.

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