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https://github.com/j-easy/easy-random

The simple, stupid random Java beans/records generator
https://github.com/j-easy/easy-random
java random random-data-generation random-generation random-number-generators
Last synced: 4 days ago
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The simple, stupid random Java beans/records generator
Host: GitHub
URL: https://github.com/j-easy/easy-random
Owner: j-easy
License: mit
Created: 2013-05-18T16:43:32.000Z (over 11 years ago)
Default Branch: master
Last Pushed: 2024-02-29T16:31:59.000Z (11 months ago)
Last Synced: 2025-01-16T22:03:28.241Z (11 days ago)
Topics: java, random, random-data-generation, random-generation, random-number-generators
Language: Java
Homepage: https://github.com/j-easy/easy-random/wiki
Size: 3.07 MB
Stars: 1,620
Watchers: 38
Forks: 234
Open Issues: 23
Metadata Files:
- Readme: README.md
- License: LICENSE.txt
Awesome Lists containing this project

README

        ***



    Easy Random


    The simple, stupid random Java™ objects generator





[![MIT license](http://img.shields.io/badge/license-MIT-brightgreen.svg?style=flat)](http://opensource.org/licenses/MIT)

[![Build Status](https://github.com/j-easy/easy-random/workflows/Java%20CI/badge.svg)](https://github.com/j-easy/easy-random/actions)

[![Maven Central](https://maven-badges.herokuapp.com/maven-central/org.jeasy/easy-random-core/badge.svg?style=flat)](https://repo1.maven.org/maven2/org/jeasy/easy-random-core/5.0.0/)

[![Javadocs](http://www.javadoc.io/badge/org.jeasy/easy-random-core.svg)](http://www.javadoc.io/doc/org.jeasy/easy-random-core)

[![Project status](https://img.shields.io/badge/Project%20status-Maintenance-orange.svg)](https://img.shields.io/badge/Project%20status-Maintenance-orange.svg)



***

## Project status

As of November 15, 2020, Easy Random is in maintenance mode. This means only bug fixes will be addressed from now on (except

for [records support](https://github.com/j-easy/easy-random/issues/397) which will be released when Java 16 is out).

Version 5.0.x (based on Java 11) and version 4.3.x (based on Java 8) are the only supported versions

for now. Please consider upgrading to one of these versions at your earliest convenience.

## Latest news

* 15/11/2020: Easy Random v5.0.0 is out and is now based on Java 11. Feature wise, this release is the same as v4.3.0. Please check the [release notes](https://github.com/j-easy/easy-random/releases/tag/easy-random-5.0.0) for more details.

* 07/11/2020: Easy Random v4.3.0 is now released with support for generic types and fluent setters! You can find all details in the [change log](https://github.com/j-easy/easy-random/releases/tag/easy-random-4.3.0).

# What is Easy Random ?

Easy Random is a library that generates random Java objects. You can think of it as an [ObjectMother](https://martinfowler.com/bliki/ObjectMother.html) for the JVM. Let's say you have a class `Person` and you want to generate a random instance of it, here we go:

```java

EasyRandom easyRandom = new EasyRandom();

Person person = easyRandom.nextObject(Person.class);

```

The method `EasyRandom#nextObject` is able to generate random instances of any given type.

# What is this EasyRandom API ?

The `java.util.Random` API provides 7 methods to generate random data: `nextInt()`, `nextLong()`, `nextDouble()`, `nextFloat()`, `nextBytes()`, `nextBoolean()` and `nextGaussian()`.

What if you need to generate a random `String`? Or say a random instance of your domain object?

Easy Random provides the `EasyRandom` API that extends `java.util.Random` with a method called `nextObject(Class type)`.

This method is able to generate a random instance of any arbitrary Java bean.

The `EasyRandomParameters` class is the main entry point to configure `EasyRandom` instances. It allows you to set all

parameters to control how random data is generated:

```java

EasyRandomParameters parameters = new EasyRandomParameters()

   .seed(123L)

   .objectPoolSize(100)

   .randomizationDepth(3)

   .charset(forName("UTF-8"))

   .timeRange(nine, five)

   .dateRange(today, tomorrow)

   .stringLengthRange(5, 50)

   .collectionSizeRange(1, 10)

   .scanClasspathForConcreteTypes(true)

   .overrideDefaultInitialization(false)

   .ignoreRandomizationErrors(true);

EasyRandom easyRandom = new EasyRandom(parameters);

```

For more details about these parameters, please refer to the [configuration parameters](https://github.com/j-easy/easy-random/wiki/Randomization-parameters) section.

In most cases, default options are enough and you can use the default constructor of `EasyRandom`.

Easy Random allows you to control how to generate random data through the [`org.jeasy.random.api.Randomizer`](https://github.com/j-easy/easy-random/blob/master/easy-random-core/src/main/java/org/jeasy/random/api/Randomizer.java) interface and makes it easy to exclude some fields from the object graph using a `java.util.function.Predicate`:

```java

EasyRandomParameters parameters = new EasyRandomParameters()

   .randomize(String.class, () -> "foo")

   .excludeField(named("age").and(ofType(Integer.class)).and(inClass(Person.class)));

EasyRandom easyRandom = new EasyRandom(parameters);

Person person = easyRandom.nextObject(Person.class);

```

In the previous example, Easy Random will:

* Set all fields of type `String` to `foo` (using the `Randomizer` defined as a lambda expression)

* Exclude the field named `age` of type `Integer` in class `Person`.

The static methods `named`, `ofType` and `inClass` are defined in [`org.jeasy.random.FieldPredicates`](https://github.com/j-easy/easy-random/blob/master/easy-random-core/src/main/java/org/jeasy/random/FieldPredicates.java) 

which provides common predicates you can use in combination to define exactly which fields to exclude.

A similar class called [`TypePredicates`](https://github.com/j-easy/easy-random/blob/master/easy-random-core/src/main/java/org/jeasy/random/TypePredicates.java) can be used to define which types to exclude from the object graph.

You can of course use your own `java.util.function.Predicate` in combination with those predefined predicates. 

# Why Easy Random ?

Populating a Java object with random data can look easy at first glance, unless your domain model involves many related classes. In the previous example, let's suppose the `Person` type is defined as follows:



    



**Without** Easy Random, you would write the following code in order to create an instance of the `Person` class:

```java

Street street = new Street(12, (byte) 1, "Oxford street");

Address address = new Address(street, "123456", "London", "United Kingdom");

Person person = new Person("Foo", "Bar", "[email protected]", Gender.MALE, address);

```

And if these classes do not provide constructors with parameters (may be some legacy types you can't change), you would write:

```java

Street street = new Street();

street.setNumber(12);

street.setType((byte) 1);

street.setName("Oxford street");

Address address = new Address();

address.setStreet(street);

address.setZipCode("123456");

address.setCity("London");

address.setCountry("United Kingdom");

Person person = new Person();

person.setFirstName("Foo");

person.setLastName("Bar");

person.setEmail("[email protected]");

person.setGender(Gender.MALE);

person.setAddress(address);

```

**With** Easy Random, generating a random `Person` object is done with `new EasyRandom().nextObject(Person.class)`.

The library will **recursively** populate all the object graph. That's a big difference!

## How can this be useful ?

Sometimes, the test fixture does not really matter to the test logic. For example, if we want to test the result of a new sorting algorithm, we can generate random input data and assert the output is sorted, regardless of the data itself:

```java

@org.junit.Test

public void testSortAlgorithm() {

   // Given

   int[] ints = easyRandom.nextObject(int[].class);

   // When

   int[] sortedInts = myAwesomeSortAlgo.sort(ints);

   // Then

   assertThat(sortedInts).isSorted(); // fake assertion

}

```

Another example is testing the persistence of a domain object, we can generate a random domain object, persist it and assert the database contains the same values:

```java

@org.junit.Test

public void testPersistPerson() throws Exception {

   // Given

   Person person = easyRandom.nextObject(Person.class);

   // When

   personDao.persist(person);

   // Then

   assertThat("person_table").column("name").value().isEqualTo(person.getName()); // assretj db

}

```

There are many other uses cases where Easy Random can be useful, you can find a non exhaustive list in the [wiki](https://github.com/j-easy/easy-random/wiki/use-cases).

## Extensions

* [JUnit extension](https://glytching.github.io/junit-extensions/randomBeans): Use Easy Random to generate random data in JUnit tests (courtesy of [glytching](https://github.com/glytching))

* [Vavr extension](https://github.com/xShadov/easy-random-vavr-extension): This extension adds support to randomize [Vavr](https://github.com/vavr-io/vavr) types (courtesy of [xShadov](https://github.com/xShadov))

* [Protocol Buffers extension](https://github.com/murdos/easy-random-protobuf): This extension adds support to randomize [Protocol Buffers](https://developers.google.com/protocol-buffers) generated types (courtesy of [murdos](https://github.com/murdos))

## Articles and blog posts

* [Easy testing with ObjectMothers and EasyRandom](https://www.jworks.io/easy-testing-with-objectmothers-and-easyrandom/)

* [Quick Guide to EasyRandom in Java](https://www.baeldung.com/java-easy-random)

* [Top secrets of the efficient test data preparation](https://waverleysoftware.com/blog/test-data-preparation/)

* [Random Data Generators for API Testing in Java](https://techblog.dotdash.com/random-data-generators-for-api-testing-in-java-369c99075208)

* [EasyRandom 4.0 Released](https://www.jworks.io/easyrandom-4-0-released/)

* [Type Erasure Revisited](https://www.beyondjava.net/type-erasure-revisited)

* [Generate Random Test Data With jPopulator](https://www.beyondjava.net/newsflash-generate-random-test-data-jpopulator)

## Who is using Easy Random ?

* [Netflix](https://github.com/Netflix/AWSObjectMapper/blob/v1.11.723/build.gradle#L71)

* [JetBrains](https://github.com/JetBrains/intellij-community/blob/201.6073/plugins/gradle/tooling-extension-impl/testSources/org/jetbrains/plugins/gradle/tooling/serialization/ToolingSerializerTest.kt#L8)

* [Mulesoft](https://github.com/mulesoft/mule-wsc-connector/blob/1.5.6/src/test/java/org/mule/extension/ws/ConfigEqualsTestCase.java#L14)

* [Easy Cucumber](https://github.com/osvaldjr/easy-cucumber/blob/0.0.18/pom.xml#L122)

* [Open Network Automation Platform](https://github.com/onap/vid/blob/6.0.3/vid-app-common/src/test/java/org/onap/vid/controller/MsoControllerTest.java#L43)

## Contribution

You are welcome to contribute to the project with pull requests on GitHub.

Please note that Easy Random is in [maintenance mode](https://github.com/j-easy/easy-random#project-status),

which means only pull requests for bug fixes will be considered.

If you believe you found a bug or have any question, please use the [issue tracker](https://github.com/j-easy/easy-random/issues).

## Core team and contributors

#### Core team

* [Mahmoud Ben Hassine](https://github.com/benas)

* [Pascal Schumacher](https://github.com/PascalSchumacher)

#### Awesome contributors

* [Adriano Machado](https://github.com/ammachado)

* [Alberto Lagna](https://github.com/alagna)

* [Andrew Neal](https://github.com/aeneal)

* [Aurélien Mino](https://github.com/murdos)

* [Arne Zelasko](https://github.com/arnzel)

* [dadiyang](https://github.com/dadiyang)

* [Dovid Kopel](https://github.com/dovidkopel)

* [Eric Taix](https://github.com/eric-taix)

* [euZebe](https://github.com/euzebe)

* [Fred Eckertson](https://github.com/feckertson)

* [huningd](https://github.com/huningd)

* [Johan Kindgren](https://github.com/johkin)

* [Joren Inghelbrecht](https://github.com/joinghel)

* [Jose Manuel Prieto](https://github.com/prietopa)

* [kermit-the-frog](https://github.com/kermit-the-frog)

* [Lucas Andersson](https://github.com/LucasAndersson)

* [Michael Düsterhus](https://github.com/reitzmichnicht)

* [Nikola Milivojevic](https://github.com/dziga)

* [nrenzoni](https://github.com/nrenzoni)

* [Oleksandr Shcherbyna](https://github.com/sansherbina)

* [Petromir Dzhunev](https://github.com/petromir)

* [Rebecca McQuary](https://github.com/rmcquary)

* [Rémi Alvergnat](http://www.pragmasphere.com)

* [Rodrigue Alcazar](https://github.com/rodriguealcazar)

* [Ryan Dunckel](https://github.com/sparty02)

* [Sam Van Overmeire](https://github.com/VanOvermeire)

* [Valters Vingolds](https://github.com/valters)

* [Vincent Potucek](https://github.com/punkratz312)

* [Weronika Redlarska](https://github.com/weronika-redlarska)

* [Konstantin Lutovich](https://github.com/lutovich)

* [Steven_Van_Ophem](https://github.com/stevenvanophem)

* [Jean-Michel Leclercq](https://github.com/LeJeanbono)

* [Marian Jureczko](https://github.com/mjureczko)

* [Unconditional One](https://github.com/unconditional)

* [JJ1216](https://github.com/JJ1216)

* [Sergey Chernov](https://github.com/seregamorph)

Thank you all for your contributions!

## License

The [MIT License](http://opensource.org/licenses/MIT). See [LICENSE.txt](https://github.com/j-easy/easy-random/blob/master/LICENSE.txt).