step-by-step.md

Day 0: An encrypted email...

We are facing our first project / solution of this journey.

We start by running the tests to ensure that everything compiles, and we are able to develop:

We can either run it from our IDE or in our Terminal:

dotnet test

Everything is green, we are OK to move on.

Let's take a look at the code (production and tests):

What can we learn from it?

• Structure of Encryption
  • It seems pretty easy to use, especially if we look at the usage (the tests)

• The encrypted email is already stored in the Tests

Write a new test

We can use a test to decrypt the file.

• We need to load the string from the encrypted email and can use this method from FileUtils:

public static string LoadFile(string fileName)
    => File.ReadAllText(
        Combine(
            GetDirectoryName(Assembly.GetExecutingAssembly().Location)!,
            fileName)
    );

Here is our first test:

[Fact]
public void Decrypt_Email()
    => _encryption
        .Decrypt(FileUtils.LoadFile("EncryptedEmail.txt"))
        .Should()
        // Of course we do not know what it contains so let's assert ???
        .Be("???");

The feedback is good, we can see some decrypted characters: Dear consultant, ...

Let's adapt the test to write the result in the outcome of the test (or write its content in a file as you prefer).

public class EncryptionTests(ITestOutputHelper testOutputHelper)
{
    ...
    [Fact]
    public void Decrypt_Email()
    {
        var decryptedContent = _encryption.Decrypt(FileUtils.LoadFile("EncryptedEmail.txt"));
        decryptedContent.Should().NotBeNullOrEmpty();
        // Use ITestOutputHelper to Write in the outcome of the test
        testOutputHelper.WriteLine(decryptedContent);
    }
}

Here is the result:

You stared at the screen, blinking in disbelief. Could this be a prank? But the email was detailed, with travel instructions and a digital copy of the NDA, stamped with an official-looking seal.

Wait, is it really a message from Santa?

Congratulations!!! 🥳 You are ready to go 🎅 With this exercise, you checked that you were able to:

• Open / compile and run the tests for the day00
• Find the instructions for the given day
• Find the step-by-step guide that will be published the day after each exercise