QNAP Backup Decryptor Testing Standards

Instructions for writing unit tests for the QNAP Backup Decryptor project using NUnit, FakeItEasy, and Shouldly.

Testing Framework and Tools

You must use the following testing tools:

Test Structure

Arrange-Act-Assert Pattern

All unit tests must follow the Arrange-Act-Assert (AAA) pattern:

1. **Arrange** - Set up test data, mocks, and dependencies

2. **Act** - Execute the method or functionality being tested

3. **Assert** - Verify the expected outcome using Shouldly assertions

Test Project Organization

Example:

```

MainProject: QnapBackupDecryptor

Test Project: QnapBackupDecryptor.Tests

Test Class: BackupDecryptorTests

Test Method: Decrypt_WhenFileIsEncrypted_ReturnsDecryptedContent

```

Project Setup

The test project must:

1. Reference the main project

2. Include these NuGet packages:

- NUnit

- NUnit3TestAdapter (for test runner integration)

- FakeItEasy

- Shouldly

Example Test Class

```csharp

using NUnit.Framework;

using FakeItEasy;

using Shouldly;

namespace QnapBackupDecryptor.Tests

{

[TestFixture]

public class BackupDecryptorTests

{

[Test]

public void Decrypt_WhenFileIsEncrypted_ReturnsDecryptedContent()

{

// Arrange

var mockFileReader = A.Fake<IFileReader>();

var encryptedData = new byte[] { 0x01, 0x02, 0x03 };

A.CallTo(() => mockFileReader.ReadFile(A<string>._))

.Returns(encryptedData);

var decryptor = new BackupDecryptor(mockFileReader);

// Act

var result = decryptor.Decrypt("test.enc");

// Assert

result.ShouldNotBeNull();

result.Length.ShouldBeGreaterThan(0);

}

[Test]

public void Decrypt_WhenFileNotFound_ThrowsFileNotFoundException()

{

// Arrange

var mockFileReader = A.Fake<IFileReader>();

A.CallTo(() => mockFileReader.ReadFile(A<string>._))

.Throws<FileNotFoundException>();

var decryptor = new BackupDecryptor(mockFileReader);

// Act & Assert

Should.Throw<FileNotFoundException>(() => decryptor.Decrypt("missing.enc"));

}

}

}

```

Key Guidelines

1. **Separation of Concerns**: Keep test code separate from production code

2. **Descriptive Names**: Test method names should clearly describe what is being tested and the expected outcome

3. **Mocking**: Use FakeItEasy to create test doubles for dependencies

4. **Readable Assertions**: Use Shouldly for expressive, human-readable assertions

5. **AAA Pattern**: Always structure tests with clear Arrange, Act, and Assert sections (comments optional but recommended for clarity)

Common Shouldly Assertions

Common FakeItEasy Patterns