add slice test + fix doc

plume-db-querydsl/README.md

@@ -110,10 +110,11 @@ public enum SortPath {
     private final Expression<?> path;
 
     @Nullable
-    public static SortPath fromSortKey(String sortKey) {
+    public static Expression<?> fromSortKey(String sortKey) {
         return Arrays.stream(SortPath.values())
             .filter(entry -> entry.sortKey.equals(sortKey))
             .findFirst()
+            .map(sortPath -> sortPath.path)
             .orElse(null);
     }
 }

plume-db/src/test/java/com/coreoz/plume/db/pagination/SliceTest.java

@@ -0,0 +1,26 @@
+package com.coreoz.plume.db.pagination;
+
+import org.assertj.core.api.Assertions;
+import org.junit.Test;
+
+import java.util.List;
+
+public class SliceTest {
+
+    @Test
+    public void should_map_users() {
+        User user = new User(1L, "To fetch");
+        Slice<User> page = new Slice<>(
+            List.of(user),
+            true
+        );
+
+        Slice<String> userNames = page.map(User::name);
+
+        Assertions.assertThat(userNames.items().stream().findFirst()).isNotEmpty();
+        Assertions.assertThat(userNames.items().stream().findFirst().get()).contains("To fetch");
+    }
+
+    private record User(long id, String name) {
+    }
+}