Skip to content

assignment.md

Latest commit

 

History

History
204 lines (148 loc) · 7.69 KB

assignment.md

File metadata and controls

204 lines (148 loc) · 7.69 KB

Assignment: Digital Twin

The goal of this assignment is to verify that you can apply software engineering techniques in practice. To do so, we ask that you build a React Native app for a hypothetical part of our product.

A note on using LLMs

You are welcome — and encouraged — to use LLMs (e.g. Cursor, Claude Code, Copilot, etc.) while working on this assignment. This reflects how we work day-to-day at Source AG.

That said, we expect you to have an in-depth understanding of the code you submit. During the interview we will ask you to walk us through your implementation, explain the choices you made, and discuss trade-offs. Be prepared to reason about any part of your codebase, including code that was generated with AI assistance.

Instructions

To track the state of the plants in the greenhouses, growers can create a digital twin of a plant. This twin represents the state of the plant at the moment of the measurement.

The digital twin starts with a stem, containing branches which contain fruits (bell peppers in this example).

For this assignment you have to draw the digital twin, based on a data object. This data object contains the start of the stem (root_node), the children of this node, which can also contain children.

When a fruit is selected, the sidebar opens, showing the status of the fruit. A fruit can have one of six fruit development stages. The different stages are described further in this assignment.

The user can change the selected fruit development stage by selecting another stage.

Below the stages, there is a list of toggles. These toggles are not part of this assignment and can be ignored.

Data

We will provide an API which contains all the data you need to complete this assignment.

API

The base URL for this API is provided in the invitation email for the tech assignment.

You can use the following endpoints:

  • GET /stems/<stem_id>: Retrieve a specific stem by its ID. To get you started, there is an existing stem with id 9ac45c32-64f1-4a27-b554-e3544cbbe001 that you can use.
  • PUT /stems/<stem_id>: Update a specific stem. The request body must follow the data structure described below, but you must omit the id field from the body. Returns the updated stem.
  • POST /stems: Create a new stem. The request body must follow the data structure described below, but you must omit the id field from the body. Returns the newly created stem, including its generated id.

All endpoints return application/json. A 404 is returned if the stem is not found.

Data format

Each stem has a top-level id and a root_node. The root node has one or more children, and each child can itself have children, forming a tree. Every node — including the root — also carries a list of fruits.

The level field on a child node controls how it is drawn:

  • 1 — the child grows straight up from its parent (continuing the main stem)
  • 2 — the child branches off to the side

Example data object:

{
    "id": "7b02aa08-5f06-4ac5-ae2b-fb582a2e8372",
    "root_node": {
        "level": 1,
        "id": "1",
        "children": [
            {
                "level": 1,
                "id": "2",
                "children": [],
                "fruits": [
                    {
                        "development_state": "HARVESTABLE_FRUIT",
                        "id": "fb532607-a858-4ad2-98f9-7aff6f682e92"
                    }
                ]
            },
            {
                "level": 2,
                "id": "1a",
                "children": [],
                "fruits": [
                    {
                        "development_state": "HARVESTABLE_FRUIT",
                        "id": "e3a12091-bc44-11ee-a506-0242ac120002"
                    }
                ]
            }
        ],
        "fruits": [
            {
                "development_state": "HARVESTABLE_FRUIT",
                "id": "a1b2c3d4-e5f6-7890-abcd-ef1234567890"
            }
        ]
    }
}

This code example results in this small drawing (click to enlarge):

As you can see, the root node (node 1) has two children. The first child (node 2) has level 1, so it grows straight up. The second child (node 1a) has level 2, so it branches off into a separate branch.

With more data you should end up with a drawing like this:

As TypeScript types:

type FruitDevelopmentState =
    | "BUD"
    | "FLOWER"
    | "SET_FRUIT"
    | "MATURE_GREEN_FRUIT"
    | "BREAKER_STAGE_FRUIT"
    | "HARVESTABLE_FRUIT";

interface Fruit {
    id: string;
    development_state: FruitDevelopmentState;
}

interface Node {
    id: string;
    level: 1 | 2;
    fruits: Fruit[];
    children: Node[];
}

interface Stem {
    id: string;
    root_node: Node;
}

Fruit development stages

Each node contains a list of fruits. For this assignment every node will have exactly one fruit.

The fruit object has a field development_state with the current stage of the fruit in it.

This list shows the possible fruit development states:

Image Development state Data value
Bud BUD
Flower FLOWER
Set fruit SET_FRUIT
Mature green fruit MATURE_GREEN_FRUIT
Breaker stage fruit BREAKER_STAGE_FRUIT
Harvestable fruit HARVESTABLE_FRUIT

Example IDs

We've added a few protected objects to the database, you cannot update these, but you can retrieve them using the following IDs:

  • 9ac45c32-64f1-4a27-b554-e3544cbbe001
  • b2f17a44-83e2-4c91-a763-f4655dcc0002
  • c3d28b55-94f3-5da2-b874-a5766edd0003
  • d4e39c66-a5f4-6eb3-c985-b6877fee0004

Assets

This repository contains an /assets directory where all required SVG assets can be found.

Requirements

Your solution should include the following functionality:

  1. Consume the provided API to fetch the stem data
  2. Draw the plant based on the data from the API
  3. Open a sidebar when a fruit is selected and show the fruit development stage
  4. Let the user change the selected fruit development stage
  5. Update the plant view with the newly selected stage
  6. Call the API to persist the change to the backend

Non-functional requirements

  • Use TypeScript
  • Use the latest stable version of React Native
  • The app should be optimized for running on tablets
  • This assignment is designed to be completed in 6–8 hours. The evaluation takes into account the choices you make and what you focus on given the time you have. It's up to you whether you spend less or more time on it.
  • Please make sure the final commit to your repository is done at least 24 hours before the start of your interview

Deliverables

This assignment should be delivered in the following way:

  • All code is pushed to your private copy of this repository
  • Documentation is provided in the README.md explaining how the solution works, and how to run and test it
  • Any information, (dummy) data, files, and other assets needed to run the project are included in the repository

Assessment Criteria

The solution will be assessed on the following criteria:

  • Code structure — Is the code well-organised and easy to follow?
  • Documentation — Is the README clear and complete?
  • Correctness — Are there any obvious bugs?
  • Performance — Does the solution perform well?
  • Decision-making — Can you clearly and concisely describe the process you followed and the choices you made, including any trade-offs? This applies equally to decisions made with or without AI assistance.
  • Self-awareness — Can you identify the biggest shortcomings of your solution and describe concrete steps to improve it?