arturlavrov / declarativecontracts

Small library that enforce design by contract approach in declarative manner

DeclarativeContracts

Lightweight library that enforce design by contract approach in clean and declarative manner

Design by contract is not a brand new, but really powerful technique that could make software reliable and safe from bugs. If you not familiar with this idea, please check this link.

Precondition

Precondition helps to verify that client's of your public API does not violate declared contract that you declared. For this purpose use class Require

For example:

public void SaveClientInfo(Client client)
{
    Require.That(client, (client) => clinet != null);

    //method body implementation code

}

The following lines is a little bit clumsy and hard to read. For solving this issue DeclarativeContracts contains a lot of out of the box functions that incapsulate required functionality

For instance, above checks could be done in the following manner:

public void CheckClientInfo(Client client)
{
    Require.That(clinet, Is.NotNull);

    //TODO: method code

}

Moreover Is and Has classes provide a lot of other useful methods such as:

Is.Null

Is.NotNull

Is.Default

Is.NotDefault

Is.NotOrEmptyString

Is.Positive

Is.Negative

Is.False

Is.True

Is.Odd

Is.Even

Postcondition

Postcondition helps to be sure that you public method always returns expected result and client could be sure that call if thees methods is always save

To perform postcondition check use class: Ensure.

For example:

public VerificationResult VerifyClient(Client client)
{
    Require.That(clinet, Is.NotNull);

    var verificationResult = _verificationService.VerifyClient(client);

    Ensure.That(verificationResult, Is.NotNull);
}

As you could see, this class could be easily combine with build your custom delegates or build in functions.

Q&A

declarativecontracts's Issues

Finished project documentation

Implement methods for decimal, float numbers

1. Separate this to external partial class that will be responsible only for numbers.

Finished tests for IsForNumbers class

Finished test for numbers

Add test for Is.Odd and Is.Even

Create CI pipeline

Build project and run unit tests

I believe that GitHub actions is a perfect choice for this particular project.

Add icon to package and fill in docs in NuGet.org

https://docs.microsoft.com/en-us/nuget/reference/nuspec#icon

Exhausted xml comment on public API

Set up code coverage tool

Set up code coverage tool and add it to ReadMe.md

Implement methods for collections

• має хоча б один елемент (IsNotEmpty)
• не має елементів (IsEmpty)
• всі елементи відповідають умові (щось схоже на ALL із T-SQL)
• хоча б один елемент відповідає умові (щось схоже на ANY із T-SQL)

Create simple project with usage example

Create folder example(on the same level as src)
-src
-example

And create a simple project that will demonstrate how to use lib.

Add project with Unit Tests

Design and describe how to create custom methods and use them in lib

Create an overload to specify custom text in pre and postconditions

Implement a following methods

IsPositive
IsNegative
IsZero
IsNotZero
IsOdd (хз, просто в голову прийшло, це мало б бути екстеншином якимось до примітивів)
IsEven (хз, просто в голову прийшло, це мало б бути екстеншином якимось до примітивів)

Come-up with ideas of how to implement class invariants.

Lazy instantiation of exceptions

Create ReadMe.md

Require.That(recurringJob.IsValid);

Create method that will accept just predicate.

It's needed to be done ASAP))

Add test for Is.One and Is.NotOne

Implement methods for Dates

Дати:

• чи дата в майбутньому
• чи дата в минулому
• сьогодні