C# & .NET Online Test
20 questions total, 50 minutes maximum, for mid and senior-level programmers
This C# online test covers the essential language and framework knowledge expected of a mid-to-senior .NET developer, including C# 14 and .NET 10.
Questions are built around realistic code snippets that candidates must reason through, testing genuine understanding rather than memorization.
For Companies
Use our online coding assessment to screen developers before the interview. Focus your interviews on the candidates who matter.
For Developers
Try a free sample test to check your programming skills. Get an instant PDF report showing where to improve.
Coding test includes:
C# 14 & .NET 10 - 20 Questions
- Object-Oriented Programming (OOP)
- Value Types, Reference Types, Records
- LINQ, EF Core
- Async/Await, Error Handling, IDisposable
- Miscellaneous: Null-Conditional, Lazy, Generics, Extensions
Sample C#/.NET Test Question
Consider the following C# code, which retrieves customers' information and their total purchase amounts from an MS SQL Database using the Entity Framework:
How many SQL queries will be executed against the database?
Answers
- One query
- Two queries
- Three queries
The correct answer is one query.
Answer explanation
Both the GetCustomers and GetSales methods are IQueryable. This means they return query expressions, not actual collections.
As a result, we execute a single complex query against the database (when .ToList() is called) instead of retrieving two collections separately and joining them server-side.
Why this question is important
This C# test question proves a developer's understanding of the difference between the IQueryable and IEnumerable interfaces.
It's important for C# developers to understand how the Entity Framework and LINQ to SQL interact with an SQL database.
Wrong built LINQ-To-SQL queries and misunderstanding of the differences between IQueryable and IEnumerable can cause serious performance issues, such as:
- Retrieving too much data from the SQL database; e.g. retrieving all rows from a table when only 20 entries are actually displayed at a time.
- Executing too many queries against the database; e.g. retrieving a list of customers, then executing individual queries to retrieve each customer's purchases.
- Executing overly complex queries against the database. If a query is too complex, you can actually get time-out exception. Sometimes it's preferable to split a complex query into two or more sub-queries and handle them further server-side.
Sample C# Test Report
This sample C# test report shows what employers/recruiters receive via email after a candidate completes one of our coding tests. It includes an overall score and a detailed breakdown by specific knowledge areas, providing a clear view of a candidate's coding skills.
Reports are provided in PDF format, making them easy to read, share and print.
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F.A.Q.
Does every candidate have to answer the same questions?
Yes. The C# & .NET test consists of the same questions for every candidate.
In order to properly compare candidates, they need to answer questions of the same difficulty level, and different questions always mean different difficulty levels.
However, the order of questions and answers is randomized for each applicant.
How should I interpret the exam scores?
First of all, you need to keep in mind one very important thing:
The purpose of this C# & .NET online test is not to help you find the best developers.
Its purpose is to help you avoid the worst ones.
For example, you have 5 candidates who get scores of 35, 45, 60, 65, and 80, based on a maximum possible score of 100.
We would recommend you invite the last three (those scoring 60, 65, and 80) to a live interview, not just the one who scored an 80/100.
What is the format of the test?
We chose a multiple-choice, or quiz, format for two reasons.
- It removes performance anxiety. Many developers freeze when asked to write code under time pressure while being watched. Picking an answer from a list lets them focus on the problem instead of the stress, giving you a more accurate read on their actual knowledge.
- It tests the right skill for the AI era. Today, most code is written with AI assistance. The skill that matters now is judgment: reading unfamiliar code, spotting bugs, and choosing the right approach. Multiple-choice questions built around real code snippets test exactly this.
What skill level is the test for?
The test is primarily created for mid and senior-level developers.
Resumes are easy to inflate, and "senior" means very different things at different companies. This C# & .NET skills test is a fast, objective way to find out who can actually deliver what they claim on paper.