标签：#ci

Test Isolation: A Lesson I Learned While Migrating Playwright Tests During my software engineering internship, I helped optimize our CI pipeline by identifying which E2E tests could safely run in parallel. That work quickly taught me that the biggest obstacle wasn't Playwright or Python, it was test isolation. This article is about that lesson. What is test isolation? A simple rule I now use is this: if a test can't run by itself with the same outcome, it probably isn't truly isolated. A well-isolated test should produce the same result whether it: runs by itself runs first or last runs after another test runs in parallel with hundreds of other tests To understand test isolation, it also helps to understand what state means. State isn't limited to database rows. During the migration, I found tests interacting with many different kinds of state. database records global configuration filesystem resources application caches If any of these are shared between tests, they become potential sources of hidden dependencies. How tests lose isolation As I started reading the existing test suite, I noticed a recurring pattern. Many tests assumed something about the environment instead of creating it themselves. Some expected specific data to already exist. Others modified global settings without restoring them afterward. Some searched for rows based on their position in a table instead of using a stable identifier like a name or ID. None of these looked particularly problematic when reading a single test. The problems only appeared once the entire suite started running together. One test would leave behind data another test didn't expect. A shared configuration would silently affect unrelated tests. A UI assertion would suddenly fail because another test inserted an extra row into the same table. Individually, the tests appeared independent. Together, they formed hidden dependencies. Not all shared state is equally difficult to isolate One realization that helped me reason abou

Tilt a CD or DVD under a desk lamp and a band of color sweeps across its surface. The disc is not painted; it is a spiral of microscopic pits, packed so tightly that they act on light the way a finely ruled scientific instrument does. Each wavelength of white light leaves the surface at its own angle, and your eye sees the result fanned out as a rainbow. That is a diffraction grating at work. The same principle that decorates a CD is the engine inside spectrometers that identify chemical elements, tune lasers, and read the composition of distant stars. This article explains how a grating spreads light, how to compute the angles, and where the analysis goes wrong. Why this calculation matters A prism also splits white light, but a grating does it with far more control and far more precision. Because the spreading depends on a countable number — the spacing between lines — a grating can be designed to send a chosen wavelength to a chosen angle. That predictability is what makes it the heart of the spectrometer. Spectroscopy underpins a remarkable range of work. Astronomers read a star's chemistry and velocity from the dark lines in its spectrum. Chemists identify unknown compounds by the wavelengths they absorb. Telecommunications engineers use gratings to combine and separate the many wavelengths sharing a single optical fiber. In every case the first task is the same: given the grating and the light, predict the angle at which each wavelength emerges. Get that wrong and a spectral line lands on the wrong detector pixel, and the measurement is meaningless. The core formula A diffraction grating is a surface ruled with a large number of equally spaced, parallel lines. When light passes through or reflects off it, each line acts as a source of secondary waves. Those waves interfere, and they reinforce each other only in specific directions — the directions where waves from neighboring lines arrive exactly in step. The condition for that reinforcement is the grating equ

The industry is described as a "dual-track" race. On one side are incumbents (Big Tech) with massive infrastructure and deep pockets. On the other is a wave of nimble startups specializing in specific engineering, error-correction, and simulation challenges. The sector is currently transitioning beyond the Noisy Intermediate-Scale Quantum (NISQ) era toward fault-tolerant systems and commercial quantum advantage—the point where quantum machines reliably outperform classical supercomputers for useful tasks. These companies are building the foundational cloud-accessible platforms and hardware: Amazon Braket (AWS) IBM Google Quantum AI Microsoft NVIDIA These players are driving innovation in specific qubit modalities or niches: Superconducting Qubits: Rigetti Computing, IQM, and Atlantic Quantum. Trapped Ion: IonQ, Quantinuum, and Alpine Quantum Technologies. Neutral Atom: QuEra, PASQAL, and Atom Computing. Photonic: Xanadu, PsiQuantum, and Quandela. Silicon/CMOS: Diraq and Silicon Quantum Computing. Error Correction: Riverlane and Q-CTRL are focused on the "noise" problem, helping make unstable qubits behave predictably. Software & Algorithms: Classiq (design automation) and Multiverse Computing (finance/optimization applications). Quantum-Safe Cybersecurity: PQShield and evolutionQ are developing cryptographic solutions to protect data against future quantum threats.

This story originally appeared in The Algorithm, our weekly newsletter on AI. To get stories like this in your inbox first, sign up here. OpenAI CEO Sam Altman’s oft-discussed promise that Americans will share in the wealth AI creates was in the news again last week. On Thursday, the Financial Times reported that Altman is in…

Its issues with current nuclear safety standards are termed semantic, not physical.

Bullshit is cheap but truth is expensive. Anyone with half a brain cell can post wild misinformation that goes mega viral, which wastes the time and expertise of highly trained people who feel an obligation to inform others of the truth. Today I want you to meet one of those highly-trained people, Dr. Zachary Rubin, […]

It will take several weeks for the Link spacecraft to rendezvous with NASA's Swift observatory.

It will take several weeks for the Link spacecraft to rendezvous with NASA's Swift observatory.

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In the AI era, platforms have no choice but to fight fire with fire to cull spam.

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WhatsApp now lets users reserve usernames ahead of the feature’s full rollout, making it possible to connect without sharing a phone number once usernames go live.

When a single engineer manages all the Terraform in an organisation, everything is simple. One repo, one state, one pipeline, one set of credentials. There's no coordination overhead because there's no one to coordinate with. That stops working the moment a second team needs to deploy infrastructure. And by the time you have three or four teams — networking, platform, application, security — the single-team model is actively slowing everyone down. This guide covers what breaks, how teams typically work around it, and how to set up a structure where each team owns their slice of infrastructure independently. What breaks State lock contention Terraform's state locking is per-state. When the networking team is running terraform plan , the application team's pipeline is blocked — even though they're changing completely unrelated resources. The more teams share a state, the more time everyone spends waiting. Blast radius A junior engineer deploying a new application service shouldn't be able to accidentally destroy the VPC. But if application resources and networking resources share a state, a single misconfigured terraform apply can touch anything. Code review catches some of this. Not all of it. Credential sprawl A shared pipeline needs credentials for everything — the networking team's Azure subscription, the application team's AWS account, the security team's DNS provider. Every team's secrets end up in one CI environment, accessible to anyone who can trigger a run. This fails most compliance audits. Approval bottlenecks In many organisations, one person or a small group gatekeeps all infrastructure changes. Every PR needs their review. Every apply needs their approval. The gatekeeper becomes a bottleneck not because they're slow, but because they're a single point of serialisation for all infrastructure work. Backend access as implicit access control Terraform has no built-in concept of per-team or per-workspace permissions. All workspaces in a backend share the sam

Most organisations don't live in a single cloud. You might run compute in AWS, DNS in Cloudflare, identity in Azure AD, and logging in GCP. Terraform handles each provider fine on its own, but the moment you need to coordinate across providers the tooling fights you. This guide walks through the common pain points of multi-cloud Terraform setups and the approaches teams use to cope — then shows how Snap CD makes cross-cloud dependency management a solved problem. Where it gets difficult Credential sprawl Each cloud provider has its own authentication mechanism. AWS uses IAM roles and access keys. Azure uses service principals and managed identities. GCP uses service accounts and workload identity federation. A single Terraform state that spans providers needs credentials for all of them — which means your CI runner or developer workstation holds keys to everything. That's a security problem. A compromised CI pipeline with AWS and Azure credentials exposes both clouds simultaneously. And it's an operational problem — rotating credentials means updating every pipeline that touches that state. This problem compounds at scale: Terraform couples provider processes tightly to credentials , so managing hundreds of accounts across clouds means spawning thousands of provider processes, which quickly becomes unmanageable. Provider version conflicts Terraform providers are versioned independently. Upgrading the AWS provider to fix a bug in aws_eks_cluster shouldn't require you to also test a new version of the Azure provider. But when they share a state, a terraform init -upgrade pulls new versions for everything, and a regression in one provider blocks all deployments. Terraform also lacks built-in support for instantiating multiple providers with a loop and passing providers to modules in for_each , making multi-cloud configurations especially verbose and repetitive. Blast radius across clouds A misconfigured terraform apply in a single-cloud state damages resources in one c

InfoQ has opened enrollment for a five-week AI Security & Privacy Engineering cohort for senior engineers and architects in regulated industries, focused on applying security, privacy, threat modeling, observability, and governance practices to production AI systems. By Artenisa Chatziou

A new study suggests that when our star becomes unstable in 5 billion years or so, Earth may avoid being engulfed by its fiery demise.

Notes: Prototype : a line that promises to a compiler that a certain function exists somewhere in the server or harddisk or files so it doesn't throw an error. In C, it is done with copying the declaration line of a function and adding a semicolon at the end of it. When we download / setup a specific programming language we download: the specific version of the language's compiler for your operating system and CPU the version of machine code of standard functions that the creator of the language has written that is fine tuned for our operating system and CPU the header files that has Only the prototype of the standard functions (aka functions like printf that are created by the creator of C) We need these in the compilation process: Pre-processing: compiler changing the header files calling line (#include line) with actual prototypes that are inside the header files and creates a temporary file with .i extension (temporary cause it gets deleted in the next step) that contains the prototype at the very top instead of #include line and your source code below compilation: compiler changes the entire contents of the .I file into assembly code (code written in assembly language). Here is why the specific version of compiler is important because every CPU has specific assembly language commands that are unique to it. Therefore when we setup a language we download specific assembly instructions for our own operating system and it comes handy in this step. Syntax check also happens in this step and the .I file also gets deleted. Now there comes a a.out file that we can actually see listed in our file explorer (but we only see the a.out file after the very end of compilation process but it does exist by this stage) Assembling: compiler changes assembly code (a.out file) to machine code (aka 0's and 1's). linking: compiler links your machine code and the machine code FOR the standard functions (because till now it ONLY has the prototypes of the function written in Binary, not

A study based on 47 million galaxies found that the cosmic web retains patterns on enormous scales, which could force a reevaluation of a pillar of cosmology.

A friend messaged me a photo of a sealed booster box last month with one question: "worth it?" He'd already decided, really. The chase card in that set was all over his feed, so the box felt like a good deal. I asked him to send me the pull rates instead of the hype, and we spent twenty minutes turning "worth it?" into something we could actually compute. That exercise is a small, self-contained data problem. It's also a good example of how a clean-looking model can hand you a confident number that doesn't survive contact with reality. If you like building little estimators, this one is worth doing carefully, because the interesting part isn't the formula. It's everything the formula assumes. The formula is the easy part Expected value of a box is a weighted sum. Each card you can pull has a probability and a market value, and you multiply the two across every slot the box gives you. That's it. Undergrad probability. Here's a stripped-down version for a hypothetical set. I'm using made-up numbers so nobody mistakes this for real pull data — the point is the shape of the computation, not the specific set. # One "hit slot" in a box: probabilities cover the full outcome space. # Values are illustrative market estimates in USD. hit_table = [ { " name " : " Alt-art chase " , " p " : 0.0125 , " value " : 180.00 }, { " name " : " Secret rare " , " p " : 0.030 , " value " : 45.00 }, { " name " : " Full-art rare " , " p " : 0.100 , " value " : 8.00 }, { " name " : " Standard hit " , " p " : 0.400 , " value " : 0.55 }, { " name " : " No notable hit " , " p " : 0.4575 , " value " : 0.06 }, ] assert abs ( sum ( row [ " p " ] for row in hit_table ) - 1.0 ) < 1e-9 ev_per_slot = sum ( row [ " p " ] * row [ " value " ] for row in hit_table ) hit_slots_per_box = 36 # e.g. one meaningful slot per pack ev_box = ev_per_slot * hit_slots_per_box print ( f " EV per slot: $ { ev_per_slot : . 2 f } " ) # $4.65 print ( f " EV per box: $ { ev_box : . 2 f } " ) # $167.31 The box costs $150 sea

The single hardest thing about getting paid isn't writing the invoice. It's the follow-up — knowing when to nudge a quiet client, and doing it in a tone that doesn't torch the relationship. Most tools solve this with a dumb cron job: "send a reminder 7 days after the due date." That's wrong for almost everyone, and here's why. The problem with fixed reminder schedules Payment behavior isn't uniform. One client pays like clockwork on day 32 of a "net 30" invoice — not late, just their rhythm. Another pays on day 5 but only if you remind them on day 3. A blanket "day 7 past due" reminder annoys the first client (who was always going to pay) and misses the second (who needed the poke earlier). So the real problem is per-client timing prediction , not scheduling. You want to model each client's payment distribution and act at the point where a reminder has the highest marginal effect — the moment they're most likely to convert intent into a transfer. Modeling payment rhythm as a per-client distribution Every invoice gives you a labeled data point: (sent_date, due_date, paid_date, amount, was_reminded) . Over time, per client, that's a distribution of "days from send to pay." The naive move is to average it. Don't — averages hide the shape, and the shape is the whole signal. We model each client's pay-day as a distribution and track two things that matter more than the mean: Dispersion — a tight distribution (always day 30–32) means a reminder before day 30 is noise. A wide one means the client is reminder-sensitive. Reminder lift — comparing paid-day distributions with and without a nudge tells you whether reminders actually move this client, and by how much. for client in clients : hist = paid_events ( client ) # list of days-to-pay p50 , p90 = quantiles ( hist , [. 5 , . 9 ]) lift = mean ( days_without_reminder ) - mean ( days_with_reminder ) # act just before the client's own habitual pay point, # but only if a nudge historically helps them if lift > MIN_LIFT_DAYS :