diff --git a/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/avis/converter/AvisConverter.java b/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/avis/converter/AvisConverter.java
new file mode 100644
index 0000000..5c5d44a
--- /dev/null
+++ b/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/avis/converter/AvisConverter.java
@@ -0,0 +1,27 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.avis.converter;
+
+import fr.iut_fbleau.but3.dev62.mylibrary.avis.AvisDTO;
+import fr.iut_fbleau.but3.dev62.mylibrary.avis.AvisInfo;
+import fr.iut_fbleau.but3.dev62.mylibrary.avis.entity.Avis;
+
+public final class AvisConverter {
+
+  private AvisConverter() {
+  }
+
+  public static Avis toDomain(AvisInfo avisInfo) {
+    return Avis.builder()
+        .clientId(avisInfo.clientId())
+        .livreId(avisInfo.livreId())
+        .note(avisInfo.note())
+        .commentaire(avisInfo.commentaire())
+        .dateAchat(avisInfo.dateAchat())
+        .build();
+  }
+
+  public static AvisDTO toDTO(Avis avis) {
+    return AvisDTO.builder()
+        .avisId(avis.getId())
+        .build();
+  }
+}
\ No newline at end of file
diff --git a/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/avis/usecase/AvisUseCase.java b/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/avis/usecase/AvisUseCase.java
new file mode 100644
index 0000000..7c43fb4
--- /dev/null
+++ b/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/avis/usecase/AvisUseCase.java
@@ -0,0 +1,40 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.avis.usecase;
+
+import fr.iut_fbleau.but3.dev62.mylibrary.avis.AvisDTO;
+import fr.iut_fbleau.but3.dev62.mylibrary.avis.AvisInfo;
+import fr.iut_fbleau.but3.dev62.mylibrary.avis.converter.AvisConverter;
+import fr.iut_fbleau.but3.dev62.mylibrary.avis.entity.Avis;
+import fr.iut_fbleau.but3.dev62.mylibrary.avis.exception.NotValidAvisException;
+import fr.iut_fbleau.but3.dev62.mylibrary.avis.repository.AvisRepository;
+import fr.iut_fbleau.but3.dev62.mylibrary.avis.validator.AvisValidator;
+import fr.iut_fbleau.but3.dev62.mylibrary.customer.exception.CustomerNotFoundException;
+import fr.iut_fbleau.but3.dev62.mylibrary.customer.repository.CustomerRepository;
+import java.util.Optional;
+import java.util.UUID;
+
+public final class AvisUseCase {
+
+  private final AvisRepository avisRepository;
+  private final CustomerRepository customerRepository;
+
+  public AvisUseCase(AvisRepository avisRepository, CustomerRepository customerRepository) {
+    this.avisRepository = avisRepository;
+    this.customerRepository = customerRepository;
+  }
+
+  public AvisDTO gererAvis(AvisInfo avisInfo) throws NotValidAvisException, CustomerNotFoundException {
+    AvisValidator.validate(avisInfo);
+
+    customerRepository.findById(avisInfo.clientId())
+        .orElseThrow(() -> new CustomerNotFoundException(avisInfo.clientId()));
+
+    Avis avis = AvisConverter.toDomain(avisInfo);
+    Avis savedAvis = avisRepository.save(avis);
+
+    return AvisConverter.toDTO(savedAvis);
+  }
+
+  public Optional<AvisDTO> findAvisById(UUID uuid) {
+    return avisRepository.findById(uuid).map(AvisConverter::toDTO);
+  }
+}
\ No newline at end of file