Library::removeBookById() updates the revision

include/library.h

@@ -332,8 +332,8 @@ class Library
   /**
    * Return the current revision of the library.
    *
-   * The revision of the library is updated (incremented by one) only by
-   * the addBook() operation.
+   * The revision of the library is updated (incremented by one) by
+   * the addBook() and removeBookById() operations.
    *
    * @return Current revision of the library.
    */

src/library.cpp

@@ -221,7 +221,11 @@ bool Library::removeBookById(const std::string& id)
   // Having a too big cache is not a problem here (or it would have been before)
   // (And setMaxSize doesn't actually reduce the cache size, extra cached items
   //  will be removed in put or getOrPut).
-  return mp_impl->m_books.erase(id) == 1;
+  const bool bookWasRemoved = mp_impl->m_books.erase(id) == 1;
+  if ( bookWasRemoved ) {
+    ++mp_impl->m_revision;
+  }
+  return bookWasRemoved;
 }
 
 Library::Revision Library::getRevision() const

test/library.cpp

@@ -801,8 +801,14 @@ TEST_F(LibraryTest, removeBooksNotUpdatedSince)
     lib.addBook(lib.getBookByIdThreadSafe(id));
   }
 
+  EXPECT_GT(lib.getRevision(), rev);
+
+  const uint64_t rev2 = lib.getRevision();
+
   EXPECT_EQ(9u, lib.removeBooksNotUpdatedSince(rev));
 
+  EXPECT_GT(lib.getRevision(), rev2);
+
   EXPECT_FILTER_RESULTS(kiwix::Filter(),
     "Islam Stack Exchange",
     "Movies & TV Stack Exchange",