1 files changed, 62 insertions, 0 deletions
diff --git a/src/main/java/org/junit/runner/manipulation/Orderer.java b/src/main/java/org/junit/runner/manipulation/Orderer.java
new file mode 100644
index 0000000..eb13054
--- /dev/null
+++ b/src/main/java/org/junit/runner/manipulation/Orderer.java
@@ -0,0 +1,62 @@
+package org.junit.runner.manipulation;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+import org.junit.runner.Description;
+
+/**
+ * Orders tests.
+ *
+ * @since 4.13
+ */
+public final class Orderer  {
+    private final Ordering ordering;
+
+    Orderer(Ordering delegate) {
+        this.ordering = delegate;
+    }
+
+    /**
+     * Orders the descriptions.
+     *
+     * @return descriptions in order
+     */
+    public List<Description> order(Collection<Description> descriptions)
+            throws InvalidOrderingException {
+        List<Description> inOrder = ordering.orderItems(
+                Collections.unmodifiableCollection(descriptions));
+        if (!ordering.validateOrderingIsCorrect()) {
+            return inOrder;
+        }
+
+        Set<Description> uniqueDescriptions = new HashSet<Description>(descriptions);
+        if (!uniqueDescriptions.containsAll(inOrder)) {
+            throw new InvalidOrderingException("Ordering added items");
+        }
+        Set<Description> resultAsSet = new HashSet<Description>(inOrder);
+        if (resultAsSet.size() != inOrder.size()) {
+            throw new InvalidOrderingException("Ordering duplicated items");
+        } else if (!resultAsSet.containsAll(uniqueDescriptions)) {
+            throw new InvalidOrderingException("Ordering removed items");
+        }
+
+        return inOrder;
+    }
+
+    /**
+     * Order the tests in <code>target</code>.
+     *
+     * @throws InvalidOrderingException if ordering does something invalid (like remove or add
+     * children)
+     */
+    public void apply(Object target) throws InvalidOrderingException {
+        if (target instanceof Orderable) {
+            Orderable orderable = (Orderable) target;
+            orderable.order(this);
+        }
+    }
+}