Unit Testing With Random Data

In 2019, while I was working on benchmark tests for my new book on code & app performance, I wanted to use “real-world” data types like a person or a coordinate along with methods for creating random words, email addresses, URLs, etc. After I worked on the code, I thought that most of it could be re-used by myself in other projects, so I moved it into an assembly. Then I thought others might like to use it so then I turned it into a NuGet package!

 

The new .NET Standard 2.0 assembly and NuGet package is called dotNetTips.Utility.Standard.Tester. The main goal is to make it simple to create these real-world objects along with lots of other methods to create random data. Some of the methods include the use of fixed-length strings that I needed for the benchmark tests. I’m even starting to use this assembly on projects where I work.

 

I will next describe some of the methods and objects I use the most.

 

Person Types

 

For the benchmark tests for my performance book, I created three Person types that reflect different ways that I see developers create data model classes. All of them implement from the IPerson interface that defines these properties,

 

Address1	Address2	BornOn
CellPhone	City	Country
Email	FirstName	HomePhone
Id	LastName	PostalCode

 

The three different types that implement IPerson are,

 

Person

 

This type represents how I see most model classes created for use in web API service calls or Entity Framework by implementing the properties in IPerson as auto-implemented properties.

 

PersonFixed

 

This type is implemented the same as Person, adds a property for Age and implements methods for the ICoparable<T> and IEquatable<T> interfaces. It also overrides GetHashCode(), ToString() and Equals() and implements operators. It also uses the DebuggerDisplay attribute.

 

PersonProper

 

This type is implemented the same as PersonFixed and adds validation to all appropriate properties. It also uses the Serializable, XmlRoot and DataContract attributes. The type represents how most data objects should be implemented and should usually be the one that you should use in your tests.

 

Along with those types, there is a PersonCollection<> that is used to return a collection of any types that implement IPerson.

 

Coordinate Types

 

Also, for my benchmark tests, I created two structure types that implement the ICoordinate interface. The interface has only two properties, X and Y. The two different types that implement ICoordinate are,

 

Coordinate

 

This structure implements X and Y as auto-implemented properties. It implements the IEquatable<> interface. It also overrides ToString(), Equals() and GetHashCode(). It implements operators (since structures do not by default have them) and uses the Serializable attribute.

 

CoordinateProper

 

This structure is implemented the same as Coordinate and implements the IComparable and IComparable<> interfaces. This structure should be used most often in your tests.

 

Random Data Methods

 

Using random data is very important if you are testing processing in your assemblies. I don’t know how many times in the past I forgot to test a last name value that includes an apostrophe which can cause SQL Server inserts or updates to fail. Humans aren’t very good at coming up with random data, code can solve that.

 

So, I created the RandomData static type that helps with generating random data. There are many methods in this class, and I add new ones often, especially when working on a new edition of my books. The methods are listed below along with sample output (most from using ? in the Immediate Window in Visual Studio).

 

Method	Output
GenerateCharacter()	82 'R'
GenerateCharacter(char minValue, char maxValue)	65 'A'
GenerateCoordinate<T>()	X: 178765551 Y: -2145952440
GenerateCoordinateCollection<T>(int count)	[0]: {2089369587--284215139} [1]: {244137335-1577361939}
GenerateDecimal(decimal minValue, decimal maxValue, int decimalPlaces)	95.15
GenerateDomainExtension()	.co.uk
GenerateEmailAddress()	[email protected]
GenerateFile(string fileName, int fileLength)	c:\\temp\\UnitTest.test
GenerateFiles(int count, int fileLength)	Path: "C:\\Users\\dotNetDave\\AppData\\Local\\Temp\\" Files: Count = 100 Raw View: ("C:\\Users\\david\\AppData\\Local\\Temp\\", {System.Collections.Generic.List<string>})
GenerateFiles(int count = 100, int fileLength, string fileExtension)	Path: "C:\\Users\\dotNetDave\\AppData\\Local\\Temp\\" Files: Count = 100 Raw View: ("C:\\Users\\david\\AppData\\Local\\Temp\\", {System.Collections.Generic.List<string>})
GenerateFiles(string path, int count, int fileLength)	[0]: "c:\\temp\\dobybcyx.lj" [1]: "c:\\temp\\zo2ggwub.3ro"
GenerateInteger(int min, int max)	100
GenerateKey()	f7f0af78003d4ab194b5a4024d02112a
GenerateNumber(int length)	446085072052112
GeneratePerson<T>(int addressLength, int cityLength, int countryLength, int firstNameLength, int lastNameLength, int postalCodeLength	N/A
GeneratePersonCollection<T>	[0]:"[email protected]" [1]:"[email protected]"
GeneratePhoneNumberUSA()	284-424-2216
GenerateRandomFileName()	C:\\Users\\dotNetDave\\AppData\\Local\\Temp\\3nvoblq5.lz1
GenerateRandomFileName(string path)	c:\\temp\\0yiv4iiu.uuv
GenerateRandomFileName(int fileNameLength, string extension)	C:\\Users\\dotNetDave\\AppData\\Local\\Temp\\FOGWYNDRBM.dotnettips
GenerateRandomFileName(string path, int fileNameLength, string extension)	C:\\temp\\FFDHRBMDXP.dotnettips
GenerateRelativeUrl()	/ljsylu/rsglcurkiylqld/wejdbuainlgjofnv/uwbrjftyt/
GenerateTempFile(int fileLength)	C:\\Users\\dotNetDave\\AppData\\Local\\Temp\\klxpckpo.24h
GenerateUrl()	https://www.agngbgluhawxhnmoxvdogla.hdtmdjmiagwlx.com/r/ulhekwhqnicq/
GenerateUrlHostName()	https://www.ehvjnbhcpcivgiccugim.lfa.net
GenerateUrlHostnameNoProtocol()	www.wucqcapnybi.kejdwudpbstekhxic.co.uk
GenerateUrlHostnameNoSubdomain()	elqqcw.org.uk
GenerateUrlPart()	/rregyyjxpjiats
GenerateWord(int length)	mL_g[E_E_CsoJvjshI]CFjFKa
GenerateWord(int minLength, int maxLength)	oMOYxlFvqclVQK
GenerateWord(int length, char minCharacter, char maxCharacter)	LBEEUMHHHK
GenerateWord(int minLength, int maxLength, char minCharacter, char maxCharacter)	ACRNFTPAE

 

All methods in RandomData have corresponding unit tests.

 

Usage Examples

 

To install the NuGet package, run the following from the Package Manager Console in Visual Studio,

 

Install-Package dotNetTips.Utility.Standard.Tester

 

This is an example of how I use this package in one of my benchmark projects.

[Benchmark]
public void SortDelegateTest()
{
  var collection =
      RandomData.GeneratePersonCollection<PersonProper>(100);

  collection.Sort(delegate (PersonProper p1, PersonProper p2)
  {
    return p1.LastName.CompareTo(p2.LastName);
  });

  base.Consumer.Consume(collection);
}

Here is how I use it in a unit test project.

[TestMethod]
public void AddItemsToCachTest()
{
  var cache = InMemoryCache.Instance;

  for (int count = 0; count < 100; count++)
  {
    cache.AddCacheItem<int>(key: RandomData.GenerateKey(),
            item: RandomData.GenerateInteger(count, 1000000);
  }
  Assert.IsTrue(cache.Count == 100);
}

Summary

 

I hope that you will check out the dotNetTips.Utility.Standard.Tester NuGet package for use in your testing projects. Need something added? I hope you will contribute to the project on GitHub.