Lydia Cupery on Atomic Spin

TypeScript

Representing a Discriminated Union in SQL

You can represent types with both shared and type-specific attributes as a discriminated union in TypeScript. Let's model that relationship in a database.

Exploratory Testing

How I Use Git Bisect to Find Where My Test Broke

When I wanted to find out exactly when my test started failing, I used the Git bisect tool to find the specific commit that caused my test to fail.

TypeScript

Requiring or Explicitly Excluding Component Properties with TypeScript

In a recent project, I want the user to provide a name for all required fields unless it's explicitly excluded. We used Typescript to do this.

Development Practices

“I Call Shotgun” – Contributing as the Navigator When Pair Programming

While pair programming, having an engaged navigator can prevent the driver from wasting time on pesky syntax errors or little logic errors.

Web Apps

Adding End to End Cypress to a Web Project Part 3: Getting Set Up with Cypress & Seeding the Database Between Tests

This post will cover the basics of getting Cypress installed and ready to go, writing a placeholder test, and resetting the test database between tests.

Web Apps

Adding End to End Cypress to a Web Project Part 1: Setting Up the Infrastructure

Setting up end-to-end Cypress testing from scratch for an existing application can be a bit intimidating, so we broke the process down into smaller steps.

JavaScript

Refresher on JavaScript Callbacks and Promises

When reviewing some legacy code, I found I needed a refresher on the difference between JavaScript callbacks and Promises.

Development

PostgreSQL Isolation Levels: How much money is actually in Piper’s bank account?

PostgreSQL transaction isolation levels (Read Uncommitted, Read Committed, Repeatable Read, Serializable Isolation) illustrated with banking transactions.

Development

Versioned Records – Part 3: Prevent Overlapping Ranges with Database-Level Exclusion Constraints

How to Use a PostgreSQL exclusion constraint to prevent overlaps in the date ranges of versioned records.

Development

Versioned Records – Part 2: Looking up a Record with Variable Attributes

When we look up a record, we usually want both the versioned attributes and the stable attributes — without having to worry about which are which.

Development

Versioned Records – Part 1: Storing Variable Attributes in a Version Table

Records may have variable attributes that change over time. To find which variable attributes are effective for a given date, we maintain a few invariants.

Web Apps

Scrollable Grid with Just-in-Time Data Loading – Part 5: Hooking Up the Database

How to update our GraphQL resolver to query our database, creating a truly full-stack implementation of just-in-time data loading.

Lydia Cupery

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