diff --git a/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/entity/BookTest.java b/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/entity/BookTest.java
index 14fe7da..1af2d9a 100644
--- a/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/entity/BookTest.java
+++ b/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/entity/BookTest.java
@@ -55,7 +55,7 @@ public class BookTest {
     }
 
     @Nested
-    @DisplayName("Loyalty Points Tests")
+    @DisplayName("Stock Tests")
     class StockTests {
 
         @Test
@@ -147,4 +147,22 @@ public class BookTest {
             assertTrue(exception.getMessage().contains(String.valueOf(book.getStock())));
         }
     }
+
+    @Nested
+    @DisplayName("Price Tests")
+    class PriceTests {
+        @Test
+        @DisplayName("addCopy should correctly increment stocks")
+        void testAddCopy() {
+            Book book =Book.builder()
+                    .stock(5)
+                    .build();
+            Integer copyToAdd = 5;
+            Integer copyExpected = 10;
+
+            book.addStock(copyToAdd);
+
+            assertEquals(copyExpected, book.getStock());
+        }
+    }
 }
diff --git a/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/IllegalBookStockExceptionTest.java b/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/IllegalBookStockExceptionTest.java
new file mode 100644
index 0000000..2a8f91a
--- /dev/null
+++ b/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/IllegalBookStockExceptionTest.java
@@ -0,0 +1,71 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.exception;
+
+import fr.iut_fbleau.but3.dev62.mylibrary.customer.exception.IllegalCustomerPointException;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+
+import java.text.MessageFormat;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class IllegalBookStockExceptionTest {
+
+    @Test
+    @DisplayName("Exception message should contain the needed and actual stock")
+    void testExceptionMessageContainsStock() {
+        int neededStock = 100;
+        int actualStock = 50;
+
+        IllegalBookStockException exception = new IllegalBookStockException(neededStock, actualStock);
+
+        String expectedMessage = "Cannot remove 100 copy from 50 copy";
+        assertEquals(expectedMessage, exception.getMessage());
+    }
+
+    @ParameterizedTest
+    @CsvSource({
+            "100, 50",
+            "75, 25",
+            "200, 150",
+            "1000, 750"
+    })
+    @DisplayName("Exception message should be formatted correctly for different stock values")
+    void testExceptionMessageForDifferentStockValues(int neededStock, int actualStock) {
+        IllegalBookStockException exception = new IllegalBookStockException(neededStock, actualStock);
+
+        String expectedMessage = MessageFormat.format(IllegalBookStockException.CANNOT_REMOVE_COPY, neededStock, actualStock);
+        assertEquals(expectedMessage, exception.getMessage());
+    }
+
+    @Test
+    @DisplayName("Exception should use the correct constant message format")
+    void testExceptionUsesConstantMessageFormat() {
+        int neededStock = 100;
+        int actualStock = 50;
+
+        IllegalBookStockException exception = new IllegalBookStockException(neededStock, actualStock);
+
+        String expectedFormatWithPlaceholder = "Cannot remove {0} copy from {1} copy";
+        assertEquals(IllegalBookStockException.CANNOT_REMOVE_COPY,
+                expectedFormatWithPlaceholder);
+        assertTrue(exception.getMessage().contains(String.valueOf(neededStock)));
+        assertTrue(exception.getMessage().contains(String.valueOf(actualStock)));
+    }
+
+    @Test
+    @DisplayName("Exception should be properly thrown and caught")
+    void testExceptionCanBeThrownAndCaught() {
+        int neededStock = 100;
+        int actualStock = 50;
+
+        try {
+            throw new IllegalBookStockException(neededStock, actualStock);
+        } catch (IllegalBookStockException e) {
+            String expectedMessage = String.format("Cannot remove %d copy from %d copy", neededStock, actualStock);
+            assertEquals(expectedMessage, e.getMessage());
+        }
+    }
+}