diff --git a/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/avis/repository/AvisRepository.java b/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/avis/repository/AvisRepository.java
new file mode 100644
index 0000000..a48d1c4
--- /dev/null
+++ b/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/avis/repository/AvisRepository.java
@@ -0,0 +1,56 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.avis.repository;
+
+import fr.iut_fbleau.but3.dev62.mylibrary.avis.entity.Avis;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Optional;
+import java.util.UUID;
+import lombok.NoArgsConstructor;
+
+@NoArgsConstructor
+public final class AvisRepository {
+
+  private final List<Avis> avisList = new ArrayList<>();
+
+  public List<Avis> findAll() {
+    return avisList;
+  }
+
+  public void deleteAll() {
+    avisList.clear();
+  }
+
+  public Avis save(Avis newAvis) {
+    Optional<Avis> existing = this.findById(newAvis.getId());
+    existing.ifPresentOrElse(avisList::remove, newAvis::setRandomUUID);
+    this.avisList.add(newAvis);
+    return newAvis;
+  }
+
+  public Optional<Avis> findById(UUID uuid) {
+    return this.avisList.stream()
+        .filter(avis -> avis.getId().equals(uuid))
+        .findFirst();
+  }
+
+  public boolean existsById(UUID uuid) {
+    return this.avisList.stream()
+        .anyMatch(avis -> avis.getId().equals(uuid));
+  }
+
+  public List<Avis> findByLivreId(UUID livreId) {
+    return this.avisList.stream()
+        .filter(avis -> avis.getLivreId().equals(livreId))
+        .toList();
+  }
+
+  public List<Avis> findByClientId(UUID clientId) {
+    return this.avisList.stream()
+        .filter(avis -> avis.getClientId().equals(clientId))
+        .toList();
+  }
+
+  public void delete(Avis avis) {
+    avisList.remove(avis);
+  }
+}
\ No newline at end of file
diff --git a/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/avis/validator/AvisValidator.java b/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/avis/validator/AvisValidator.java
new file mode 100644
index 0000000..0f4d0d8
--- /dev/null
+++ b/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/avis/validator/AvisValidator.java
@@ -0,0 +1,54 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.avis.validator;
+
+import fr.iut_fbleau.but3.dev62.mylibrary.avis.AvisInfo;
+import fr.iut_fbleau.but3.dev62.mylibrary.avis.exception.NotValidAvisException;
+
+public final class AvisValidator {
+
+  public static final String CLIENT_ID_CANNOT_BE_NULL = "Client id cannot be null";
+  public static final String LIVRE_ID_CANNOT_BE_NULL = "Livre id cannot be null";
+  public static final String NOTE_MUST_BE_BETWEEN_1_AND_5 = "Note must be between 1 and 5";
+  public static final String COMMENTAIRE_CANNOT_BE_BLANK = "Commentaire cannot be blank";
+  public static final String DATE_ACHAT_CANNOT_BE_NULL = "Date achat cannot be null";
+
+  private AvisValidator() {
+  }
+
+  public static void validate(AvisInfo avisInfo) throws NotValidAvisException {
+    validateClientId(avisInfo);
+    validateLivreId(avisInfo);
+    validateNote(avisInfo);
+    validateCommentaire(avisInfo);
+    validateDateAchat(avisInfo);
+  }
+
+  private static void validateClientId(AvisInfo avisInfo) throws NotValidAvisException {
+    if (avisInfo.clientId() == null) {
+      throw new NotValidAvisException(CLIENT_ID_CANNOT_BE_NULL);
+    }
+  }
+
+  private static void validateLivreId(AvisInfo avisInfo) throws NotValidAvisException {
+    if (avisInfo.livreId() == null) {
+      throw new NotValidAvisException(LIVRE_ID_CANNOT_BE_NULL);
+    }
+  }
+
+  private static void validateNote(AvisInfo avisInfo) throws NotValidAvisException {
+    if (avisInfo.note() < 1 || avisInfo.note() > 5) {
+      throw new NotValidAvisException(NOTE_MUST_BE_BETWEEN_1_AND_5);
+    }
+  }
+
+  private static void validateCommentaire(AvisInfo avisInfo) throws NotValidAvisException {
+    if (avisInfo.commentaire() == null || avisInfo.commentaire().isBlank()) {
+      throw new NotValidAvisException(COMMENTAIRE_CANNOT_BE_BLANK);
+    }
+  }
+
+  private static void validateDateAchat(AvisInfo avisInfo) throws NotValidAvisException {
+    if (avisInfo.dateAchat() == null) {
+      throw new NotValidAvisException(DATE_ACHAT_CANNOT_BE_NULL);
+    }
+  }
+}
\ No newline at end of file