Spargine is a collection of open-source assemblies and NuGet packages designed for .NET 10, which I have been developing and maintaining since the release of .NET Framework 2. These assemblies are not only a core part of my projects but are also actively deployed in production environments across several companies I collaborate with.

Get Spargine

You can access the source code and NuGet packages here:

• GitHub: Spargine 10
• NuGet: dotNetDaveNuGet

In 2019, while developing benchmark tests for the first edition of my code performance book, I needed realistic “real-world” data types—such as people, addresses, and coordinates—along with utilities to generate random words, email addresses, URLs, and more. Once that work was complete, it became clear that this functionality was far too useful to live only inside a single book project.

I consolidated the code into its own assembly and, recognizing its broader applicability, published it as a NuGet package so it could be reused across unit tests, benchmark projects, and real-world applications.

With the arrival of .NET 10, the assembly—now released as DotNetTips.Spargine.Tester—has seen significant enhancements. Its core mission remains the same: make it easy to generate realistic data and domain objects for testing and benchmarking. New features include benchmark-friendly helpers (such as fixed-length string generators) and expanded support for real-world data scenarios. This assembly is now actively used across multiple production and professional projects.

Person Types

For the benchmark tests in my performance book, I designed a Person type that demonstrates best practices in API design, implementation, and documentation. In the latest version of the package, the original reference-type Person has been expanded into three variants:

• Reference type (RefTypes.Person)
• Value type (ValueTypes.Person)
• Record type (PersonRecord)

All implementations conform to the IPerson interface, making it easy to compare performance characteristics across representations.

Constructor

• Person(string email, string id)
  Initializes a new instance of the class with the specified email and id.

Properties

Methods

• Create(string id, string email, string firstName, string lastName, DateTimeOffset? bornOn, Collection<Address>? addresses, string? cellPhone, string? phone)
  Creates a new Person with the specified values.
• ToPerson(Person person)
  Converts Person to ValueTypes.Person.
• ToPerson(PersonRecord person)
  Converts PersonRecord to a Person.
• ToPerson(ValueTypes.Person person)
  Converts ValueTypes.Person to Person.
• ToString()
  Returns a string representation of the Person.

To further improve performance, a dedicated JsonSerializerContext is included for optimized serialization and deserialization of individual Person instances and collections.

PersonExtensions

This version of the assembly introduces extension properties for the Person types:

• FullName
  Gets the full name of the person by concatenating the first and last names.
• Age
  Gets the age of the person as a TimeSpan since their birth date.

Address Types

Address types represent structured address data, including street information, city, state, country, postal code, and phone number. All address implementations—including record variants—implement the IAddress<TSelf> interface.

Constructors

• Address(string id)
  Initializes a new instance of the class with the specified identifier.
• Address(string id, string address1, string city, string country, string postalCode)
  Initializes a new instance of the class with the specified identifier, address line 1, city, country, and postal code.

Properties

Methods

• Create(string Id)
  Creates a new Address with only the identifier.
• Create(string id, string address1, string city, string country, string postalCode, string? address2, string? countyProvince, string? state, string? phone)
  Factory method to create a new Address instance with the specified values.
• ToAddress(Address address)
  Converts a reference Address to AddressRecord.
• ToAddress(AddressRecord address)
  Converts an AddressRecord to Address.
• ToAddress(ValueTypes.Address address)
  Converts a ValueTypes.Address to Address.
• ToString()
  Returns a human-readable representation of this address instance for diagnostics.

Coordinate Type

To support spatial and numeric benchmarks, the package includes a Coordinate implementation that adheres to the ICoordinate interface, which exposes X, Y, and Z properties. Both reference and value-type implementations are provided to support comparative benchmarking.

Random Data Methods

Randomized input is essential for meaningful tests. Developers often underestimate edge cases—such as last names with apostrophes—that can expose bugs in validation logic or database operations. Humans are poor at generating truly random data, but code excels at it.

The RandomData static class exists to solve this problem. It provides a large and continually expanding set of methods for generating realistic, randomized data. New methods are frequently added as new benchmarking scenarios emerge.

Below is a selection of available methods with representative output.

Realistic Person and Address Information

The Person and Address generation logic has been enhanced so that most data—excluding Address1 and Address2—is generated in a country-aware manner. The process randomly selects a country, then derives valid states, cities, phone numbers, and postal codes based on that country. First names, last names, and email addresses are generated to reflect real-world patterns.

As a result, generated data now closely resembles actual production data, making it far more valuable for realistic testing, demos, and benchmarks.

Future work includes improving the realism of Address1 and Address2, which is planned but intentionally deferred.

{

  "Address1": "yB[kEjKkUqcQLxG][odoUcIEy",

  "Address2": "CnsfNH^tL_YWN^Fb[ca\\pfZFi",

  "BornOn": "1957-04-09T16:08:45.8948496-07:00",

  "CellPhone": "3140713855",

  "City": "Floridsdorf",

  "Country": "Austria",

  "Email": "Courtney.Coronado@vemyy.shoes",

  "FirstName": "Courtney",

  "HomePhone": "0258058628",

  "Id": "1c88785618f84e73b5e07172adb63f93",

  "LastName": "Coronado",

  "PostalCode": "5888",

  "State": "Vienna"

}

Country Data and Lookup

This assembly includes country, state, and city data for all countries worldwide, accessible through the CountryRepository.

var countries = Countries.GetCountries();

These are the class models that will be returned.

Additional retrieval methods include:

• GetCountry(CountryName countryName)
  Retrieves country information based on a value from the CountryName Enum.
• GetCountry(string countryNameOrIso)
  Retrieves a country by its name or ISO code.

RandomCreditCardNumberGenerator

The RandomCreditCardNumberGenerator produces realistic, valid credit card numbers suitable for testing (not real accounts).

Available methods include:

• GetCreditCardNumber()
  Generate a single random credit card number. Supported credit cards include: American Express, Diners Club, Discover, EnRoute, JCB, MasterCard, Visa, and Voyager.
• GetCreditCardNumbers(int count)
   Generates a collection of random credit card numbers. Supported credit cards include: American Express, Diners Club, Discover, EnRoute, JCB, MasterCard, Visa, and Voyager.

Summary

The DotNetTips.Spargine.Tester assembly removes the friction from creating realistic, repeatable, and benchmark-friendly test data. Whether you’re writing unit tests, building performance benchmarks, validating edge cases, or demonstrating real-world scenarios, this library gives you a rich set of tools to generate meaningful data quickly and consistently.

By offering reference types, value types, and records side by side, the package also enables precise performance comparisons—making it especially valuable for benchmarking and performance-focused development. The inclusion of country-aware data, optimized serialization contexts, and cryptographically secure randomness further elevates it beyond simple “fake data” generators.

Finally, be sure to explore the UnitTester utilities included in this assembly, which add even more capabilities to your unit testing workflow. Together, these tools help you write better tests, run more accurate benchmarks, and build more resilient .NET applications with confidence.

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