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writing-mstest-tests

Write and modernize MSTest unit tests using MSTest 3.x/4.x assertion APIs and conventions.

Updated Aug 9, 2026
Search Tags:#csharp#unit testing#dotnet#assertions#mstest#data-driven tests#test modernization
One-click install
npx skills add https://github.com/adinj00/player-performance --skill writing-mstest-tests-adinj00
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: writing-mstest-tests
Source: https://github.com/adinj00/player-performance/tree/main/.agents/skills/writing-mstest-tests
Command: npx skills add https://github.com/adinj00/player-performance --skill writing-mstest-tests-adinj00

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve? Writing MSTest unit tests often leads to outdated patterns like [ExpectedException], generic Assert.IsTrue checks, swapped AreEqual arguments, and MSTESTxxxx analyzer warnings. This Skill guides you through writing, fixing, and modernizing MSTest 3.x/4.x tests with current APIs and best practices. ## Core Features & Use Cases - Modern assertion APIs: Replace Assert.IsTrue with specific assertions like IsEmpty, HasCount, Contains, IsInstanceOfType, and ThrowsExactly for clearer failure messages. - Data-driven and lifecycle patterns: Implement DataRow, DynamicData with ValueTuples, constructor-based initialization, TestContext injection, and cancellation token usage. - Analyzer fixes: Resolve MSTESTxxxx diagnostics with the idiomatic code fix for each rule. - Use Case: You inherit a test suite full of Assert.IsTrue(list.Count > 0) and [ExpectedException] attributes. Use this Skill to convert them to Assert.IsNotEmpty and Assert.ThrowsExactly, fix swapped AreEqual arguments, and clear all analyzer warnings. ## Quick Start Ask the AI to write MSTest unit tests for your C# class using modern MSTest 3.x assertions and data-driven patterns.

Frequently Asked Questions about writing-mstest-tests

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I write MSTest unit tests with modern assertions?▼

Use specific Assert methods instead of Assert.IsTrue: Assert.IsEmpty for empty collections, Assert.HasCount for counts, Assert.Contains for membership, and Assert.ThrowsExactly for exceptions. Follow the Arrange-Act-Assert pattern with [TestClass] and [TestMethod] attributes.

How to replace ExpectedException attribute in MSTest?▼

Replace [ExpectedException] with Assert.ThrowsExactly<T>(() => code) for synchronous code or await Assert.ThrowsExactlyAsync<T> for async code. ThrowsExactly matches only the exact exception type, while Throws also matches derived types.

What is the correct argument order for Assert.AreEqual in MSTest?▼

Assert.AreEqual takes the expected value first and the actual value second: Assert.AreEqual(expected, actual). Swapped arguments trigger the MSTEST0017 analyzer diagnostic and produce confusing failure messages.

Does MSTest support data-driven tests with DynamicData?▼

Yes, MSTest supports [DataRow] for inline values and [DynamicData] for complex data. MSTest 3.7+ prefers ValueTuple return types over IEnumerable<object[]> for type safety, and TestDataRow<T> adds per-case metadata like DisplayName.

When should I not use this MSTest writing approach?▼

Do not use it for test quality audits or flaky-test investigations, running tests, or migrating between MSTest versions. It also does not apply to xUnit, NUnit, TUnit, or non-.NET languages.

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