Package org.instancio.junit

Class InstancioExtension

java.lang.Object

org.instancio.junit.InstancioExtension

All Implemented Interfaces:

org.junit.jupiter.api.extension.AfterAllCallback, org.junit.jupiter.api.extension.AfterEachCallback, org.junit.jupiter.api.extension.AfterTestExecutionCallback, org.junit.jupiter.api.extension.BeforeAllCallback, org.junit.jupiter.api.extension.BeforeEachCallback, org.junit.jupiter.api.extension.Extension, org.junit.jupiter.api.extension.ParameterResolver

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

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
• injecting fields and method parameters using @Given aannotation

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	afterAll(org.junit.jupiter.api.extension.ExtensionContext context)
void	afterEach(org.junit.jupiter.api.extension.ExtensionContext context)
void	afterTestExecution(org.junit.jupiter.api.extension.ExtensionContext context)
void	beforeAll(org.junit.jupiter.api.extension.ExtensionContext context)
void	beforeEach(org.junit.jupiter.api.extension.ExtensionContext context)
Object	resolveParameter(org.junit.jupiter.api.extension.ParameterContext parameterContext, org.junit.jupiter.api.extension.ExtensionContext extensionContext)
boolean	supportsParameter(org.junit.jupiter.api.extension.ParameterContext parameterContext, org.junit.jupiter.api.extension.ExtensionContext extensionContext)	For methods, JUnit invokes (1) beforeEach(), (2) resolveParameter() For constructors, the order is reverse.

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

beforeAll

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

Specified by:

beforeAll in interface org.junit.jupiter.api.extension.BeforeAllCallback

beforeEach

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

Specified by:

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

Throws:

IllegalAccessException

afterAll

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

Specified by:

afterAll in interface org.junit.jupiter.api.extension.AfterAllCallback

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

supportsParameter

public boolean supportsParameter(org.junit.jupiter.api.extension.ParameterContext parameterContext,
 org.junit.jupiter.api.extension.ExtensionContext extensionContext)

For methods, JUnit invokes (1) beforeEach(), (2) resolveParameter() For constructors, the order is reverse. As a result, when resolveParameter() is called, the setup logic hasn't been run yet. For this reason, constructor parameters are not supported.

Specified by:

supportsParameter in interface org.junit.jupiter.api.extension.ParameterResolver

resolveParameter

public Object resolveParameter(org.junit.jupiter.api.extension.ParameterContext parameterContext,
 org.junit.jupiter.api.extension.ExtensionContext extensionContext)

Specified by:

resolveParameter in interface org.junit.jupiter.api.extension.ParameterResolver