SimCorp Coding Challenge

Assignment

Write a program that will determine the type of a triangle.

• It should take the lengths of the triangle’s three sides as input and return whether the triangle is equilateral, isosceles, or scalene.
• We are looking for solutions that showcase problem-solving skills and structural considerations that can be applied to larger and potentially more complex problem domains.
• Pay special attention to tests, readability, and error cases.

Solution

The solution is written as a .Net Web API project.

The solution is structured in 4 source projects:

• Api - The Web API project (this is the project that is started when the application is started)
• Application - The application logic (the core of the application; this is limited in this case, but in a real-world application, this would be the place to put the application logic)
• Domain - The domain model and logic (business logic of the application)
• Contracts - The contracts for the application (response records in this case)

And 2 test projects:

• Api.Tests - Integration tests for the Web API testing the full from request to response (using the WebApplicationFactory)
• Domain.Tests - Unit tests for the domain logic

Usage

The Web API is hosted on https://shapeclassification.azurewebsites.net.

The API has one endpoint: /shape. The endpoint accepts a GET request with a Query param called sides ?sides=202,205,196 (for now, the endpoint only supports triangles; the endpoint could easily be extended to support quadrants, for example).

The sides query param is a comma-separated list of integers or doubles (using . as a decimal separator).

The endpoint returns a JSON response with the classification of the shape, the type, and the sides of the requested shape.

{
  "value": {
    "classification": "Scalene",
    "type": "Triangle",
    "sides": [
      202,
      205,
      196
    ]
  }
}

In the TypeOfShape.Api project, there is a ShapeClassification.http file that can be used to test the API.

Three different host environments for the HTTP file can be used:

• prod - The production environment (the deployed API on Azure)
• local-https - The local environment using HTTPS
• local-http - The local environment using HTTP

Error handling

The API contains error handling for the following cases:

• The sides provided are not able to be parsed into a list of numbers
• There are not exactly three sides provided
• Invalid Input (not a number, negative number, zero, etc.)
• Invalid triangle (flat triangle, impossible triangle, etc.)

Example error response:

{
  "error": {
    "code": "TriangleErrors.FlatTriangleError",
    "message": "Triangle is flat"
  }
}

Packages

The solution uses the following packages:

Source projects

• ErrorOr - A package providing a fluent discriminated union for error and result handling

Test projects

• xunit - A unit testing framework
• FluentAssertions - A package providing fluent assertions for unit testing
• Microsoft.AspNetCore.Mvc.Testing - A package providing a WebApplicationFactory for integration testing
• coverlet.collector - A package providing code coverage for unit testing