Staff User Importer — technical exercise

Thanks for taking the time to do this. It’s designed to take about 2–4 hours. We’re not looking for a polished product — we’re interested in how you read unfamiliar code, isolate a problem, and make focused changes across a Vue front end and a GraphQL/PHP back end.

The scenario

“AcmeLearn” runs a learning platform. Each night, HR exports a CSV of staff and we import it into the platform’s user store (a SQLite database, to keep this exercise self-contained). This repository contains a small web app for doing that import: a Vue 3 single-page app that talks to a GraphQL API in PHP, which in turn drives the import pipeline.

Each row in the export carries an hr_id — the employee’s identifier in the HR system the data comes from. The platform’s own user store assigns its own surrogate id on insert; hr_id is kept as the stable reference back to HR.

You don’t need any prior knowledge of our products to do this exercise.

What’s in the box

api/                       GraphQL API layer (thin glue over the pipeline)
  bootstrap.php            Autoloading + the SQLite connection
  graphql/schema.graphql   The GraphQL schema (SDL)
  Schema.php               Builds the schema and dispatches to resolvers by name
  resolvers/               One file per operation (query/, mutation/)
  UserMapper.php           Maps store rows <-> GraphQL fields
public/
  router.php               Entry point for the PHP built-in server
  graphql.php              The /graphql endpoint
src/                       The import pipeline (plain PHP, independent of the API)
  CsvReader.php             Reads the CSV into rows
  UserValidator.php         Validates a single row
  UserRepository.php        Reads/writes users in the store
  ImportRunner.php          Orchestrates the import and builds the summary
  ImportSummary.php         Collects results for the report
client/                    Vue 3 SPA (Vite)
  src/views/               Import and Users pages
  src/components/           UserTable, ResultsSummary
  src/composables/          useGraphql (useQuery / useMutation)
tests/                     PHPUnit test suite
data/users.csv             A sample HR export
schema.sql                 The user-store schema

Requirements

• PHP 8.1+ with the PDO SQLite extension (pdo_sqlite)
• Composer
• Node 18+ — needed for front-end development (npm run dev) and the Vue tests. The app can be demoed with PHP alone if client/dist is present (it’s committed for convenience).

Running it

# 1. Install PHP dependencies
composer install

# 2. Build the front end (first time, or after changing client/ code)
cd client && npm install && npm run build && cd ..

# 3. Serve the app + API on one origin
php -S localhost:8080 public/router.php
# open http://localhost:8080

While working on the front end, run the Vite dev server for hot reload — it proxies /graphql to the PHP server, so keep the PHP server running too:

cd client && npm run dev          # http://localhost:5173

The store is written to data/users.sqlite. Delete that file to start from a clean store.

Running the tests

composer install && ./vendor/bin/phpunit      # PHP / API
cd client && npm install && npm run test      # Vue components + composable

Your tasks

1. Fix the broken import (required)

QA have filed a ticket:

Importing data/users.csv through the app fails partway through with a database error, and at least one member of staff from the file never makes it into the store. The data in the CSV looks fine to us, and the GraphQL response just shows a database error.

Running the PHP test suite, you’ll find one failing test that reproduces this (ImportRunnerTest::testEveryValidRowIsPersisted). Track down the root cause, fix it, and get the suite green. In your write-up, briefly explain what was actually going wrong. Resist the urge to paper over it (swallowing the exception, INSERT OR IGNORE, de-duplicating rows) — the missing member of staff must actually end up in the store.

2. Support updating users (required)

Right now the importer can only ever create users, and there’s no way to correct a user once they’re imported.

• (a) Make the import an upsert. If a member of staff is already in the store, re-running the import should update them in place rather than failing; new staff are still created. The results summary should distinguish records that were created from those that were updated.
• (b) Add an “edit user” flow to the SPA that calls the updateUser mutation and reflects the change in the list. Add a new page, an inline editor — whatever you think fits best.

The GraphQL schema already declares updated and the updateUser mutation. Wire them through the resolvers, the existing UserRepository / ImportSummary, and the UI. Add or adjust PHPUnit and Vue tests as you see fit.

3. Handling a very large file (optional — if you have time)

The app base64-encodes the whole file into a single GraphQL request, and CsvReader reads the entire CSV into memory before processing it. Imagine the nightly export grows to several hundred thousand rows. How would you change the transport and the pipeline to handle that without exhausting memory or timing out? A written explanation is fine if you don’t have time to implement it; partial code plus notes is also welcome.

Submitting

Please send us a git repository (with your commit history) codebase, plus a short note covering:

• the root cause of the bug in task 1, and how you fixed it;
• the approach you took for task 2 and any trade-offs;
• your thinking on task 3;
• anything you’d do with more time, or chose deliberately not to do.

We value clear, minimal changes that fit the existing code over large rewrites.