Package org.instancio.junit

Class InstancioExtension

java.lang.Object

org.instancio.junit.InstancioExtension

All Implemented Interfaces:

org.junit.jupiter.api.extension.AfterEachCallback, org.junit.jupiter.api.extension.AfterTestExecutionCallback, org.junit.jupiter.api.extension.BeforeEachCallback, org.junit.jupiter.api.extension.Extension

public class InstancioExtension
extends Object
implements org.junit.jupiter.api.extension.BeforeEachCallback, org.junit.jupiter.api.extension.AfterEachCallback, org.junit.jupiter.api.extension.AfterTestExecutionCallback

The Instancio JUnit extension adds support for additional features when using Instancio with JUnit Jupiter:

• reporting the seed value to allow reproducing failed tests
• injecting Settings using @WithSettings annotation
• generating parameterized test arguments using @InstancioSource

Reproducing failed tests

The extension generates a seed for each test method. When a test fails, the extension reports this seed in the output. Using the Seed annotation, the test can be re-run with the reported seed to reproduce the data that caused the failure.

For example, given the following test class:

 @ExtendWith(InstancioExtension.class)
 class ExampleTest {

     @Test
     void verifyPerson() {
         Person person = Instancio.create(Person.class);
         // some test code...
         // ... some assertion fails
     }
 }
 

The failed test will report the seed value that was used, for example:

"Test method 'verifyPerson' failed with seed: 12345"

Subsequently, the failing test can be reproduced by annotating the test method with the Seed annotation:

 @Test
 @Seed(12345) // will reproduce previously generated data
 void verifyPerson() {
     Person person = Instancio.create(Person.class);
     // snip...
 }
 

See the user guide for more details.

Since:

1.1.0

Constructor Summary

Constructors

Constructor	Description
InstancioExtension()	Default constructor; required for JUnit extensions.
InstancioExtension(org.instancio.support.ThreadLocalRandom threadLocalRandom, org.instancio.support.ThreadLocalSettings threadLocalSettings)

Method Summary

Modifier and Type	Method	Description
void	afterEach(org.junit.jupiter.api.extension.ExtensionContext context)
void	afterTestExecution(org.junit.jupiter.api.extension.ExtensionContext context)
void	beforeEach(org.junit.jupiter.api.extension.ExtensionContext context)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

InstancioExtension

public InstancioExtension()

Default constructor; required for JUnit extensions.

InstancioExtension

InstancioExtension(org.instancio.support.ThreadLocalRandom threadLocalRandom,
 org.instancio.support.ThreadLocalSettings threadLocalSettings)

Method Details

beforeEach

public void beforeEach(org.junit.jupiter.api.extension.ExtensionContext context)

Specified by:

beforeEach in interface org.junit.jupiter.api.extension.BeforeEachCallback

afterEach

public void afterEach(org.junit.jupiter.api.extension.ExtensionContext context)

Specified by:

afterEach in interface org.junit.jupiter.api.extension.AfterEachCallback

afterTestExecution

public void afterTestExecution(org.junit.jupiter.api.extension.ExtensionContext context)

Specified by:

afterTestExecution in interface org.junit.jupiter.api.extension.AfterTestExecutionCallback