diff --git a/mylibrary/src/main/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/BookAlreadyExistsException.java b/mylibrary/src/main/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/BookAlreadyExistsException.java
new file mode 100644
index 0000000..a21df9e
--- /dev/null
+++ b/mylibrary/src/main/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/BookAlreadyExistsException.java
@@ -0,0 +1,13 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.exception;
+
+import java.text.MessageFormat;
+
+public class BookAlreadyExistsException extends Exception {
+
+  public static final String A_BOOK_WITH_ISBN_ALREADY_EXISTS_MESSAGE = "A book with isbn {0} already exists";
+
+  public BookAlreadyExistsException(long isbn) {
+    // ISBN passe en String pour ne pas que MessageFormat ajoute le separateur de milliers
+    super(MessageFormat.format(A_BOOK_WITH_ISBN_ALREADY_EXISTS_MESSAGE, String.valueOf(isbn)));
+  }
+}
diff --git a/mylibrary/src/main/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/BookNotFoundException.java b/mylibrary/src/main/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/BookNotFoundException.java
new file mode 100644
index 0000000..679f2aa
--- /dev/null
+++ b/mylibrary/src/main/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/BookNotFoundException.java
@@ -0,0 +1,13 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.exception;
+
+import java.text.MessageFormat;
+
+public class BookNotFoundException extends Exception {
+
+  public static final String THE_BOOK_WITH_ISBN_DOES_NOT_EXIST_MESSAGE = "The book with isbn {0} does not exist";
+
+  public BookNotFoundException(long isbn) {
+    // ISBN passe en String pour ne pas que MessageFormat ajoute le separateur de milliers
+    super(MessageFormat.format(THE_BOOK_WITH_ISBN_DOES_NOT_EXIST_MESSAGE, String.valueOf(isbn)));
+  }
+}
diff --git a/mylibrary/src/main/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/IllegalBookQuantityException.java b/mylibrary/src/main/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/IllegalBookQuantityException.java
new file mode 100644
index 0000000..9dd11ef
--- /dev/null
+++ b/mylibrary/src/main/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/IllegalBookQuantityException.java
@@ -0,0 +1,12 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.exception;
+
+import java.text.MessageFormat;
+
+public class IllegalBookQuantityException extends Exception {
+
+  public static final String CANNOT_REMOVE_STOCK = "Cannot remove {0} units from {1} units in stock";
+
+  public IllegalBookQuantityException(int needed, int actual) {
+    super(MessageFormat.format(CANNOT_REMOVE_STOCK, needed, actual));
+  }
+}
diff --git a/mylibrary/src/main/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/NotValidBookException.java b/mylibrary/src/main/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/NotValidBookException.java
new file mode 100644
index 0000000..6eab151
--- /dev/null
+++ b/mylibrary/src/main/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/NotValidBookException.java
@@ -0,0 +1,8 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.exception;
+
+public class NotValidBookException extends Exception {
+
+  public NotValidBookException(String message) {
+    super(message);
+  }
+}
diff --git a/mylibrary/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/BookAlreadyExistsExceptionTest.java b/mylibrary/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/BookAlreadyExistsExceptionTest.java
new file mode 100644
index 0000000..f19a9fe
--- /dev/null
+++ b/mylibrary/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/BookAlreadyExistsExceptionTest.java
@@ -0,0 +1,26 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.exception;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class BookAlreadyExistsExceptionTest {
+
+  @Test
+  @DisplayName("Exception message should contain the ISBN provided")
+  void testExceptionMessageContainsIsbn() {
+    long isbn = 9780321125217L;
+
+    BookAlreadyExistsException exception = new BookAlreadyExistsException(isbn);
+
+    assertTrue(exception.getMessage().contains(String.valueOf(isbn)));
+  }
+
+  @Test
+  @DisplayName("Exception should expose its message constant")
+  void testConstantMessage() {
+    assertEquals("A book with isbn {0} already exists",
+        BookAlreadyExistsException.A_BOOK_WITH_ISBN_ALREADY_EXISTS_MESSAGE);
+  }
+}
diff --git a/mylibrary/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/BookNotFoundExceptionTest.java b/mylibrary/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/BookNotFoundExceptionTest.java
new file mode 100644
index 0000000..1a0cfe2
--- /dev/null
+++ b/mylibrary/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/BookNotFoundExceptionTest.java
@@ -0,0 +1,37 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.exception;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class BookNotFoundExceptionTest {
+
+  @Test
+  @DisplayName("Exception message should contain the ISBN provided")
+  void testExceptionMessageContainsIsbn() {
+    long isbn = 9780321125217L;
+
+    BookNotFoundException exception = new BookNotFoundException(isbn);
+
+    assertTrue(exception.getMessage().contains(String.valueOf(isbn)));
+  }
+
+  @Test
+  @DisplayName("Exception should expose its message constant")
+  void testConstantMessage() {
+    assertEquals("The book with isbn {0} does not exist",
+        BookNotFoundException.THE_BOOK_WITH_ISBN_DOES_NOT_EXIST_MESSAGE);
+  }
+
+  @Test
+  @DisplayName("Exception should be properly thrown and caught")
+  void testExceptionCanBeThrownAndCaught() {
+    long isbn = 1L;
+    try {
+      throw new BookNotFoundException(isbn);
+    } catch (BookNotFoundException e) {
+      assertTrue(e.getMessage().contains("1"));
+    }
+  }
+}
diff --git a/mylibrary/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/IllegalBookQuantityExceptionTest.java b/mylibrary/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/IllegalBookQuantityExceptionTest.java
new file mode 100644
index 0000000..1aa191f
--- /dev/null
+++ b/mylibrary/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/IllegalBookQuantityExceptionTest.java
@@ -0,0 +1,33 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.exception;
+
+import java.text.MessageFormat;
+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 static org.junit.jupiter.api.Assertions.*;
+
+class IllegalBookQuantityExceptionTest {
+
+  @Test
+  @DisplayName("Exception message should contain the requested and actual quantities")
+  void testExceptionMessageContainsQuantities() {
+    IllegalBookQuantityException exception = new IllegalBookQuantityException(10, 3);
+    String expected = "Cannot remove 10 units from 3 units in stock";
+    assertEquals(expected, exception.getMessage());
+  }
+
+  @ParameterizedTest
+  @CsvSource({
+      "10, 3",
+      "100, 0",
+      "5, 4"
+  })
+  @DisplayName("Message should be formatted using the constant template")
+  void testFormattedMessage(int needed, int actual) {
+    IllegalBookQuantityException exception = new IllegalBookQuantityException(needed, actual);
+    String expected = MessageFormat.format(IllegalBookQuantityException.CANNOT_REMOVE_STOCK, needed, actual);
+    assertEquals(expected, exception.getMessage());
+  }
+}
diff --git a/mylibrary/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/NotValidBookExceptionTest.java b/mylibrary/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/NotValidBookExceptionTest.java
new file mode 100644
index 0000000..5f826b5
--- /dev/null
+++ b/mylibrary/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/NotValidBookExceptionTest.java
@@ -0,0 +1,44 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.exception;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class NotValidBookExceptionTest {
+
+  @Test
+  @DisplayName("Exception should be created with the provided message")
+  void testExceptionCreation() {
+    String msg = "title cannot be blank";
+    NotValidBookException exception = new NotValidBookException(msg);
+    assertEquals(msg, exception.getMessage());
+  }
+
+  @ParameterizedTest
+  @ValueSource(strings = {
+      "Title cannot be blank",
+      "Author cannot be blank",
+      "Price must be strictly positive",
+      "At least one category is required"
+  })
+  @DisplayName("Exception should propagate any validation message")
+  void testExceptionWithDifferentMessages(String message) {
+    NotValidBookException exception = new NotValidBookException(message);
+    assertEquals(message, exception.getMessage());
+  }
+
+  @Test
+  @DisplayName("Exception should be catchable as a general Exception")
+  void testExceptionInheritance() {
+    String msg = "invalid book";
+    try {
+      throw new NotValidBookException(msg);
+    } catch (Exception e) {
+      assertEquals(NotValidBookException.class, e.getClass());
+      assertEquals(msg, e.getMessage());
+    }
+  }
+}