diff --git a/mylibrary/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/entity/BookTest.java b/mylibrary/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/entity/BookTest.java
new file mode 100644
index 0000000..91b012d
--- /dev/null
+++ b/mylibrary/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/entity/BookTest.java
@@ -0,0 +1,75 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.entity;
+
+import fr.iut_fbleau.but3.dev62.mylibrary.book.exception.IllegalBookQuantityException;
+import java.time.LocalDate;
+import java.util.List;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class BookTest {
+
+  @Test
+  @DisplayName("Builder should create a valid Book instance")
+  void testBookBuilder() {
+    long isbn = 9780321125217L;
+    Book book = Book.builder()
+        .isbn(isbn)
+        .title("Domain-Driven Design")
+        .author("Eric Evans")
+        .publisher("Addison-Wesley")
+        .publicationDate(LocalDate.of(2003, 8, 22))
+        .price(54.99)
+        .quantity(10)
+        .categories(List.of(Category.SCIENCE, Category.REFERENCE))
+        .description("Tackling complexity in the heart of software")
+        .language("EN")
+        .build();
+
+    assertEquals(isbn, book.getIsbn());
+    assertEquals("Domain-Driven Design", book.getTitle());
+    assertEquals("Eric Evans", book.getAuthor());
+    assertEquals("Addison-Wesley", book.getPublisher());
+    assertEquals(LocalDate.of(2003, 8, 22), book.getPublicationDate());
+    assertEquals(54.99, book.getPrice());
+    assertEquals(10, book.getQuantity());
+    assertEquals(List.of(Category.SCIENCE, Category.REFERENCE), book.getCategories());
+    assertEquals("EN", book.getLanguage());
+  }
+
+  @Nested
+  @DisplayName("Stock management")
+  class StockTests {
+
+    @Test
+    @DisplayName("addStock should increase the quantity")
+    void testAddStock() {
+      Book book = Book.builder().quantity(5).build();
+      book.addStock(7);
+      assertEquals(12, book.getQuantity());
+    }
+
+    @Test
+    @DisplayName("removeStock should decrease the quantity")
+    void testRemoveStock() throws IllegalBookQuantityException {
+      Book book = Book.builder().quantity(5).build();
+      book.removeStock(3);
+      assertEquals(2, book.getQuantity());
+    }
+
+    @Test
+    @DisplayName("removeStock should throw when removing more than available")
+    void testRemoveTooMuchStock() {
+      Book book = Book.builder().quantity(5).build();
+      IllegalBookQuantityException exception = assertThrows(
+          IllegalBookQuantityException.class,
+          () -> book.removeStock(10)
+      );
+      assertEquals(5, book.getQuantity());
+      assertTrue(exception.getMessage().contains("10"));
+      assertTrue(exception.getMessage().contains("5"));
+    }
+  }
+}