TryAtSoftware.CleanTests 1.0.0-alpha.9

About the project

TryAtSoftware.CleanTests is a library that should simplify the process of automated testing for complex setups.

The repeating pattern that we could discover in some advanced projects is that whenever more features are added or old ones are being refactored, adding new tests or modifying existing ones could be a tough challenge.

One of the private projects that uses our library has a lot of polymorphic components and every concrete implementation has a totally different logic. There were two main test assemblies - an old one (let's call it Standard for brevity) where standard patterns for testing were applied and a new one (let's call it Clean for brevity) integrating TryAtSoftware.CleanTests. We could easily compare the two approaches as we were working on them independently.

In the past, there were multiple test assemblies with more than 1500 tests that were executing for over 10 minutes. However, TryAtSoftware.CleanTests was integrated in a different assembly and we could easily compare the two approaches. Moreover, if the more components and logical branches there are in the code, the less scenarios are covered.

After finalizing the integration, we could notice the following:

As you can see, this is quite big of a difference! With much less effort we managed to achieve unthinkable results. If we had to stick to the Standard testing approach in order to increase the code coverage and amount of test cases and optimize the performance, we had to write a lot of code. And if we had to do the same for every new functionality that is coming, that would slow down the software development process significantly. TryAtSoftware.CleanTests gave us an alternative approach of automatic testing that not only improved the quality of the product but also saved us a lot of time that we could invest in adding more and more features.

The main goals that have been accomplished are:

• Automatic generation of test cases using all proper variations of registered clean utilities
• Every clean utility can define external demands that represent conditions about what other clean utilities should be present within a variation in order to generate a test case with it
• Every clean utility can depend internally on other clean utilities
• Every clean utility can define internal demands that represent conditions about what clean utilities should be injected upon initialization
• Global and local clean utilities - local clean utilities are instantiated for every test case; global clean utilities are instantiated only once and can be used to share common context between similar test cases
• Parallel execution of tests cases

About us

Try At Software is a software development company based in Bulgaria. We are mainly using dotnet technologies (C#, ASP.NET Core, Entity Framework Core, etc.) and our main idea is to provide a set of tools that can simplify the majority of work a developer does on a daily basis.

Getting started

Installing the package

Before creating any equalization profiles, you need to install the package. The simplest way to do this is to either use the NuGet package manager, or the dotnet CLI.

Using the NuGet package manager console within Visual Studio, you can install the package using the following command:

Install-Package TryAtSoftware.CleanTests

Or using the dotnet CLI from a terminal window:

dotnet add package TryAtSoftware.CleanTests

Configurations

In order to use the features of this library, there is one mandatory step that must be done. Your test assembly should be decorated with an appropriate attribute that will define which test framework should be used for the execution of test cases. Add the following line anywhere in your project (most likely this is done within an AssemblyInfo.cs file):

[assembly: Xunit.TestFramework("TryAtSoftware.CleanTests.Core.XUnit.CleanTestFramework", "TryAtSoftware.CleanTests.Core")]

Modifying behavior

Additionally, you can modify the behavior of the clean tests execution framework using the ConfigureCleanTestsFramework attribute. There is a list of the parameters that can be controlled:

• UseTraits - Indicates whether or not to add traits to each generated test case. Enabling this may have performance impact over the discovery process when dealing with a big amount of tests because of the amount of data stored in these traits. The default value is false.
• MaxDegreeOfParallelism - A value representing the maximum number of test cases executed in parallel. It should always be positive. There is no concrete formula that can be used to determine which is the most optimal value - it depends on the characteristics of the executing machine, specifics related to the test environment and many other circumstances. The default value is 5.

Example:

[assembly: TryAtSoftware.CleanTests.Core.Attributes.ConfigureCleanTestsFramework(UseTraits = true, MaxDegreeOfParallelism = 3)]

What are the clean utilities?

The clean utility is a key component for our library. Every clean utility has a category and a name that are required. One test may require many clean utilities and whenever there are two or more utilities from the same category that can be used for its execution, then a test case will be generated for each possible variation of utilities.

Every clean utility can me marked as local or global. Local clean utilities will be instantiated at least once for every test case requiring their participation. Global clean utilities will be instantiated only once for all test cases sharing a common context.

Moreover, every clean utility can optionally define its own characteristics. These characteristics can be used to filter out on some basis the utilities that we want to use when generating the cases for a given test. They do often correspond to essential segments of the requested component's behavior. We use demands to make sure that the capabilities our test needs are present for the resolved utilities used to execute the test.

In order to use a type as a clean utility, it should be marked with the CleanUtility attribute that accepts category, name and characteristics. You can also explicitly set a value to the IsGlobal flag.

Example:

[CleanUtility(Categories.Writers, "Console writer", Characteristics.UsesConsole, Characteristics.ActiveWriter)]
public class ConsoleWriter : IWriter
{
    public void Write(string text) => Console.WriteLine(text);
}

[CleanUtility(Categories.Writers, "File writer", Characteristics.UsesFile, Characteristics.ActiveWriter)]
public class FileWriter : IWriter
{
    public void Write(string text) => File.WriteAllText("C:/path_to_document", text);
}

[CleanUtility(Categories.Writers, "Fake writer")]
public class FakeWriter : IWriter
{
    public void Write(string text) { /* Do nothing */ }
}

All clean utilities should be located within the test assembly. If this is not possible, the test assembly should be explicitly decorated with an attribute denoting where the shared clean utilities are defined.

[assembly: TryAtSoftware.CleanTests.Core.Attributes.SharesUtilitiesWith("Assembly.With.Shared.CleanUtilities")]

External demands

Every clean utility can define external demands throughout the ExternalDemands attribute. With its help for each category a set of demanded characteristics can be defined. These demanded characteristics will alter the way variations of clean utilities are generated - all external demands should be satisfied for all utilities participating in the variation.

Example:

[CleanUtility(Categories.Readers, "Console reader")]
[ExternalDemands(Categories.Writers, Characteristics.UsesConsole)]
public class ConsoleReader : IReader
{
    public string Read() => Console.ReadLine();
}

Internal requirements and demands

Every clean utility can depend on other clean utiliites. This relationship can be modelled throughout the WithRequirements attribute. When such clean utility participates in a variation, that same variation will be reused as many times as the number of possible instantiation procedures there are (according to the registered clean utilities of the required categories).

Moreover, internal demands can be applied (throughout the InternalDemands attribute) to filter out the dependent clean utilities according to a predefined set of characteristics.

Example:

[CleanUtility(Categories.Engines, "Default engine")]
[WithRequirements(Categories.Readers, Categories.Writers)]
[InternalDemands(Categories.Writers, Characteristics.ActiveWriter)]
public class Engine : IEngine
{
    private readonly IReader _reader;
    private readonly IWriter _writer;
    
    public Engine(IReader reader, IWriter writer)
    {
        this._reader = reader ?? throw new ArgumentNullException(nameof(reader));
        this._writer = writer ?? throw new ArgumentNullException(nameof(writer));
    }
    
    /* further implementation of the `IEngine` interface... */
}

How to use clean tests?

This library is built atop XUnit so if you are familiar with the way this framework operates, you are most likely ready to use clean tests. There are only two requirements for this:

• The test should be marked with either CleanFact (instead of Fact) or CleanTheory (instead of Theory).

You can still use tests that are marked with other attributes, however, they will be executed as standard tests and will have none of the behavior clean tests can benefit from.

• The type containing the requested test should implement the ICleanTest interface. We suggest reusing the abstract CleanTest that we have exposed as it will make accessing instances of the registered clean utilites easier and you will not have to think about various internal processes that should be handled.

Clean tests can define requirements representing the set of categories for which clean utilities should be provided. The WithRequirements attribute can be used in order to achieve that.

Clean tests can also define demands to filter out only a specific subset of the clean utilities that can be used for the generation of test cases. The TestDemands attribute can be used in order to achieve that - for each category a set of demanded characteristics can be defined.

Example:

[CleanFact]
[WithRequirements(Categories.Writers)]
[TestDemands(Categories.Writers, Characteristics.ActiveWriter)]
public void WriteShouldSucceed()
{
    IWriter writer = this.GetService<IWriter>();
    writer.Write("Some text");
}