What methods and tools do you use to check the quality and reliability of the code?

To check the quality and reliability of code in C#, I usually use the following methods and tools:

• Unit testing with NUnit, xUnit, or MSTest. Allows testing individual components for correctness.
• Static code analysis using tools like SonarQube, ReSharper, or the built-in Visual Studio analyzer. Helps identify potential errors and style violations.
• Code reviews — an effective way to find logical errors and improve quality.
• Integration testing to verify interactions between components.
• Code coverage — to ensure that important parts of the code are tested.

Example of a simple test with NUnit:

[Test]
public void Sum_TwoNumbers_ReturnsCorrectResult()
{
    var calculator = new Calculator();
    var result = calculator.Sum(2, 3);
    Assert.AreEqual(5, result);
}