Cómo utilizar Hamcrest assertThat() Matchers para crear casos de prueba JUnit en Java – Tutorial completo

Publicado: 2022-02-05
Cómo utilizar los emparejadores de Hamcrest assertThat() para crear casos de prueba JUnit en Java

¿Cómo usar Hamcrest for testing ? Hace algún tiempo escribí un artículo JUnit de Hello World con todos los detalles. En este tutorial, repasaremos los pasos sobre how to use Hamcrest to create JUnit para su proyecto Java.

Hamcrest es un testing framework para Java con comparadores incluidos con el marco JUnit para crear pruebas de unidad de Java más legibles. Lo probé hoy y me encanta.

La documentación muy simple y completa lo hace perfecto.

Si tiene alguna de las siguientes preguntas, entonces está en el lugar correcto:

  • Escribiendo casos de prueba JUnit en Java usando Eclipse
  • Cómo escribir casos de prueba junit en Java
  • Ejemplos de casos de prueba JUnit en Java
  • Escribiendo casos de prueba JUnit usando Hamcrest Matchers
  • Los beneficios de los métodos de assertThat vs Assert a los métodos de afirmación en las pruebas JUnit
  • Hamcrest assertthat() tutorial
  • Prueba con Hamcrest

Empecemos:

Cree la clase Java CrunchifyHemcrestJUnitTest.java en Eclipse. Vamos a crear 4 categorías diferentes de pruebas.

  1. Crear casos de prueba JUnit para Java List
  2. Crear casos de prueba JUnit para Java Map
  3. Crear casos de prueba JUnit para objetos Java
  4. Crear casos de prueba JUnit para Null Check

Aquí están los mejores emparejadores de Hamcrest:

  • es()
  • tiene elementos ()
  • tieneTamaño()
  • contiene ()
  • contieneEnCualquierOrden()

El siguiente tutorial cubre casi todos los casos de prueba de emparejadores que pasarán todo el tiempo. Simplemente modifique para crear un falso positivo y así sucesivamente.

Debe agregar la dependencia maven a continuación en su proyecto.

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< dependency >
< groupId > org . hamcrest < / groupId >
< artifactId > hamcrest - all < / artifactId >
< version > 1.3 < / version >
< / dependency >

Simplemente agregue esto al archivo pom.xml . Si no ve pom.xml, siga este tutorial.

contiene en cualquier orden-hamcrest-java-junit-test

Aquí hay un código Java completo

Simplemente haga clic derecho en una clase y Run As -> JUnit Test .

CrunchifyHacrestJUnitTest.java

Java
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package crunchify . com . java . tutorials ;
 
import org . hamcrest . collection . IsEmptyCollection ;
import org . hamcrest . collection . IsMapContaining ;
import org . hamcrest . core . IsNull ;
import org . junit . Test ;
 
import java . util . * ;
 
import static org . hamcrest . CoreMatchers . * ;
import static org . hamcrest . MatcherAssert . assertThat ;
import static org . hamcrest . Matchers . hasProperty ;
import static org . hamcrest . collection . IsCollectionWithSize . hasSize ;
import static org . hamcrest . collection . IsIterableContainingInAnyOrder . containsInAnyOrder ;
import static org . hamcrest . collection . IsIterableContainingInOrder . contains ;
 
/**
* @author Crunchify.com
* <p>
* Hamcrest JUnit Tutorials by Crunchify.com
* 1. Create JUnit testcases for Java List
* 2. Create JUnit testcases for Java Map
* 3. Create JUnit testcases for Java Object
* 4. Create JUnit testcases for Null Check
*/
 
public class CrunchifyHamcrestJUnitTest {
// Testcase-1: JUnit for List
@Test
public void crunchifyListJUnitTests ( ) {
// List: An ordered collection (also known as a sequence). The user of this interface has precise control over where in the list each element is inserted.
// The user can access elements by their integer index (position in the list), and search for elements in the list.
List <String> company = Arrays . asList ( "Crunchify.com" , "Google.com" , "Facebook.com" ) ;
// asList(): Returns a fixed-size list backed by the specified array. Changes made to the array will be visible in the returned list,
// and changes made to the list will be visible in the array.
// The returned list is Serializable and implements RandomAccess.
List <String> crunchifyCompany = Arrays . asList ( "Crunchify.com" , "Google.com" , "Facebook.com" ) ;
crunchifyLog ( "\n~~~~~~~~~~~JUnit List Check Test~~~~~~~~~~~" ) ;
crunchifyLog ( "1) assertThat(company, is(crunchifyCompany)) check" ) ;
// A shortcut to the frequently used is(equalTo(x)).
assertThat ( company , is ( crunchifyCompany ) ) ;
crunchifyLog ( "2) .hasItems() check" ) ;
assertThat ( company , hasItems ( "Crunchify.com" ) ) ;
crunchifyLog ( "3) .hasSize() check" ) ;
assertThat ( company , hasSize ( 3 ) ) ;
assertThat ( company . size ( ) , is ( 3 ) ) ;
crunchifyLog ( "4) .contains() and .containsInAnyOrder() check" ) ;
assertThat ( company , contains ( "Crunchify.com" , "Google.com" , "Facebook.com" ) ) ;
assertThat ( company , containsInAnyOrder ( "Google.com" , "Crunchify.com" , "Facebook.com" ) ) ;
// FAIL
// assertThat(company, contains("Google.com", "Crunchify.com", "Facebook.com"));
crunchifyLog ( "5) .empty() check" ) ;
assertThat ( company , not ( IsEmptyCollection . empty ( ) ) ) ;
assertThat ( new ArrayList < > ( ) , IsEmptyCollection . empty ( ) ) ;
}
private void crunchifyLog ( String crunchifyText ) {
System . out . println ( crunchifyText ) ;
}
@Test
public void crunchifyMapJUnitTests ( ) {
Map < String , String > company = new HashMap < > ( ) ;
company . put ( "C" , "Crunchify.com" ) ;
company . put ( "G" , "Google.com" ) ;
company . put ( "F" , "Facebook.com" ) ;
// Map: An object that maps keys to values. A map cannot contain duplicate keys; each key can map to at most one value.
// This interface takes the place of the Dictionary class, which was a totally abstract class rather than an interface.
Map < String , String > crunchifyCompany = new HashMap < > ( ) ;
crunchifyCompany . put ( "C" , "Crunchify.com" ) ;
// put(): Associates the specified value with the specified key in this map (optional operation).
// If the map previously contained a mapping for the key, the old value is replaced by the specified value.
// (A map m is said to contain a mapping for a key k if and only if m.containsKey(k) would return true.)
crunchifyCompany . put ( "G" , "Google.com" ) ;
crunchifyCompany . put ( "F" , "Facebook.com" ) ;
crunchifyLog ( "\n~~~~~~~~~~~ JUnit Map Check Test - All tests will PASS in our example ~~~~~~~~~~~" ) ;
crunchifyLog ( "1) assertThat(company, is(crunchifyCompany) check" ) ;
assertThat ( company , is ( crunchifyCompany ) ) ;
crunchifyLog ( "2) assertThat(company.size(), is(3)) check" ) ;
assertThat ( company . size ( ) , is ( 3 ) ) ;
crunchifyLog ( "3) .hasEntry() check which creates a matcher for Maps matching at least one entry whose key equals the specified key & value." ) ;
assertThat ( company , IsMapContaining . hasEntry ( "C" , "Crunchify.com" ) ) ;
assertThat ( company , not ( IsMapContaining . hasEntry ( "G" , "Twitter.com" ) ) ) ;
crunchifyLog ( "4) .hasKey() creates a matcher for Maps matching at least one key that is equal to the specified key." ) ;
assertThat ( company , IsMapContaining . hasKey ( "F" ) ) ;
crunchifyLog ( "5) .hasValue() creates a matcher for Maps matching at least one key that is equal to the specified value." ) ;
assertThat ( company , IsMapContaining . hasValue ( "Crunchify.com" ) ) ;
}
@SuppressWarnings ( "unchecked" )
@Test
public void crunchifyObjectJUnitTests ( ) {
List <Company> list = Arrays . asList ( new Company ( "Crunchify" , 10 ) , new Company ( "Google" , 30000 ) ) ;
assertThat ( list , hasItems ( new Company ( "Crunchify" , 10 ) , new Company ( "Google" , 30000 ) ) ) ;
assertThat ( list , containsInAnyOrder ( new Company ( "Google" , 30000 ) , new Company ( "Crunchify" , 10 ) ) ) ;
assertThat ( list , containsInAnyOrder ( hasProperty ( "name" , is ( "Google" ) ) , hasProperty ( "name" , is ( "Crunchify" ) ) ) ) ;
crunchifyLog ( "\n~~~~~~~~~~~ JUnit Object Check Test Completed ~~~~~~~~~~~" ) ;
}
// Create Company Object
public static class Company {
public Company ( String name , int employeeCount ) {
this . name = name ;
this . employeeCount = employeeCount ;
}
private String name ;
private int employeeCount ;
public int getEmployeeCount ( ) {
return employeeCount ;
}
public void setEmployeeCount ( int employeeCount ) {
this . employeeCount = employeeCount ;
}
public String getName ( ) {
return name ;
}
public void setName ( String name ) {
this . name = name ;
}
// Test equal, override equals() and hashCode()
@Override
public boolean equals ( Object c ) {
if ( this == c )
return true ;
if ( c == null | | getClass ( ) ! = c . getClass ( ) )
return false ;
Company fruit = ( Company ) c ;
return employeeCount == fruit . employeeCount && Objects.equals(name, fruit.name);
}
@Override
public int hashCode ( ) {
return Objects . hash ( name , employeeCount ) ;
}
}
@Test
public void crunchifyNullCheckJUnitTest ( ) {
// Two ways to check isNull
assertThat ( null , is ( nullValue ( ) ) ) ;
assertThat ( null , is ( IsNull . nullValue ( ) ) ) ;
// Two ways to check isNotNull
assertThat ( "crunchify" , is ( notNullValue ( ) ) ) ;
assertThat ( "crunchify" , is ( IsNull . notNullValue ( ) ) ) ;
crunchifyLog ( "\n~~~~~~~~~~~ JUnit Null Check Test Completed ~~~~~~~~~~~" ) ;
}
}

Salida de la consola de Eclipse:

Simplemente ejecute el programa anterior como una aplicación Java y debería ver un resultado como el siguiente.

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~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ JUnit Object Check Test Completed ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
 
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ JUnit Null Check Test Completed ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
 
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ JUnit List Check Test ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
1 ) assertThat ( company , is ( crunchifyCompany ) ) check
2 ) . hasItems ( ) check
3 ) . hasSize ( ) check
 
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ JUnit List Check Test ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
1 ) assertThat ( company , is ( crunchifyCompany ) ) check
2 ) . hasItems ( ) check
3 ) . hasSize ( ) check
4 ) . contains ( ) and . containsInAnyOrder ( ) check
5 ) . empty ( ) check
 
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ JUnit Map Check Test - All tests will PASS in our example ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
1 ) assertThat ( company , is ( crunchifyCompany ) check
2 ) assertThat ( company . size ( ) , is ( 3 ) ) check
3 ) . hasEntry ( ) check which creates a matcher for Maps matching at least one entry whose key equals the specified key & value .
4 ) . hasKey ( ) creates a matcher for Maps matching at least one key that is equal to the specified key .
5 ) . hasValue ( ) creates a matcher for Maps matching at least one key that is equal to the specified value .
 
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ JUnit Object Check Test Completed ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
 
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ JUnit Null Check Test Completed ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
 
Process finished with exit code 0
hamcrest-java-junit-test-resultado

Háganos saber si tiene algún problema al ejecutar el programa anterior.