Add the action to get Book by a BookId.

test/decentralised_book_index/metadata/book_test.exs

@@ -117,4 +117,26 @@ defmodule DecentralisedBookIndex.Metadata.BookTest do
       assert book3.id in book_ids
     end
   end
+
+  describe "get a book by book id" do
+    test "get by bid" do
+      {:ok, author} = Metadata.create_author("Author", "An description")
+
+      type = "isbn10"
+      bid = "1234567890"
+
+      bids = [
+        %{order: 1, type: type, bid: bid}
+      ]
+
+      author_roles = [
+        %{order: 1, author_id: author.id, role: ""}
+      ]
+
+      {:ok, expected_book} = Metadata.create_book("Book", "An description", bids, author_roles)
+
+      assert {:ok, book} = Metadata.get_book_by_bid(type, bid)
+      assert expected_book.id == book.id
+    end
+  end
 end