Instancio is a Java library that automatically creates and populates objects for your unit tests.
Instead of manually setting up test data:
Address address = new Address();
address.setStreet("street");
address.setCity("city");
//...
Person person = new Person();
person.setFirstName("first-name");
person.setLastName("last-name");
person.setAge(22);
person.setGender(Gender.MALE);
person.setAddress(address);
//...You can simply do the following:
Person person = Instancio.create(Person.class);This one-liner returns a fully-populated person, including nested objects and collections.
The object is populated with random data that can be reproduced in case of test failure.
- Create collections of objects:
List<Person> persons = Instancio.ofList(Person.class).size(10).create();- Create streams of objects:
Stream<Person> persons = Instancio.stream(Person.class);- Create generic types:
Pair<List<Foo>, List<Bar>> pairOfLists = Instancio.create(new TypeToken<Pair<List<Foo>, List<Bar>>>() {});- Customise generated values:
Person person = Instancio.of(Person.class)
.generate(field(Person::getDateOfBirth), gen -> gen.temporal().localDate().past())
.generate(field(Phone::getAreaCode), gen -> gen.oneOf("604", "778"))
.generate(field(Phone::getNumber), gen -> gen.text().pattern("#d#d#d-#d#d-#d#d"))
.subtype(all(AbstractAddress.class), AddressImpl.class)
.supply(all(LocalDateTime.class), () -> LocalDateTime.now())
.onComplete(all(Person.class), (Person p) -> p.setName(p.getGender() == Gender.MALE ? "John" : "Jane"))
.create();- Create reusable templates (Models) of objects:
Model<Person> simpsons = Instancio.of(Person.class)
.set(field(Person::getLastName), "Simpson")
.set(field(Address::getCity), "Springfield")
.generate(field(Person::getAge), gen -> gen.ints().range(40, 50))
.toModel();
Person homer = Instancio.of(simpsons)
.set(field(Person::getFirstName), "Homer")
.set(all(Gender.class), Gender.MALE)
.create();
Person marge = Instancio.of(simpsons)
.set(field(Person::getFirstName), "Marge")
.set(all(Gender.class), Gender.FEMALE)
.create();- Fully reproducible data in case of test failures.
- Support for generics,
recordandsealedclasses. - Support for defining custom generators.
- Support for generating data based on Bean Validation annotations.
- Flexible configuration options.
InstancioExtensionfor Junit 5@ExtendWith.
Instancio Quickstart is the best way to get started. It is a sample (Maven) project that provides an overview of all the main features.
git clone https://github.com/instancio/instancio-quickstart.gitVersion 2.12.0 is now available.
A summary of new features is available in the release notes.
If you have JUnit 5 on the classpath, use the instancio-junit dependency.
<dependency>
<groupId>org.instancio</groupId>
<artifactId>instancio-junit</artifactId>
<version>2.12.0</version>
<scope>test</scope>
</dependency>To use Instancio with JUnit 4, TestNG, or standalone, use instancio-core:
<dependency>
<groupId>org.instancio</groupId>
<artifactId>instancio-core</artifactId>
<version>2.12.0</version>
<scope>test</scope>
</dependency>Feedback and bug reports are greatly appreciated. Please submit an issue to report a bug, or if you have a question or a suggestion.
JetBrains and YourKit for supporting this project.
