cleaned up and added test for TransformingSetSupplier

core/src/main/java/org/jclouds/collect/TransformingSetSupplier.java

@@ -19,13 +19,15 @@
 package org.jclouds.collect;
 
 import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.common.base.Predicates.notNull;
+import static com.google.common.collect.Iterables.filter;
 import static com.google.common.collect.Iterables.transform;
-import static com.google.common.collect.Sets.newLinkedHashSet;
 
 import java.util.Set;
 
 import com.google.common.base.Function;
 import com.google.common.base.Supplier;
+import com.google.common.collect.ImmutableSet;
 
 /**
  * 
@@ -42,7 +44,7 @@ public class TransformingSetSupplier<F, T> implements Supplier<Set<? extends T>>
 
    @Override
    public Set<? extends T> get() {
-      return newLinkedHashSet(transform(backingSupplier.get(), converter));
+      return ImmutableSet.copyOf(filter(transform(filter(backingSupplier.get(), notNull()), converter), notNull()));
    }
 
 }

core/src/test/java/org/jclouds/collect/TransformingSetSupplierTest.java

@@ -0,0 +1,65 @@
+/**
+ * Licensed to jclouds, Inc. (jclouds) under one or more
+ * contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  jclouds licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.jclouds.collect;
+
+import static org.testng.Assert.assertEquals;
+
+import java.util.List;
+
+import org.testng.annotations.Test;
+
+import com.google.common.base.Function;
+import com.google.common.base.Functions;
+import com.google.common.base.Suppliers;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Lists;
+
+/**
+ * 
+ * @author Adrian Cole
+ */
+@Test(groups = "unit", singleThreaded = true, testName = "TransformingSetSupplierTest")
+public class TransformingSetSupplierTest {
+   @Test
+   public void testTransform() {
+      TransformingSetSupplier<String, String> supplier = new TransformingSetSupplier<String, String>(Suppliers
+               .<Iterable<String>> ofInstance(ImmutableSet.of("foo")), Functions.forMap(ImmutableMap.of("foo", "bar")));
+      assertEquals(supplier.get(), ImmutableSet.<String> of("bar"));
+   }
+
+   @Test
+   public void testNullsNotReturnedFromSourceSupplier() {
+      List<String> ofNull = Lists.newArrayList();
+      ofNull.add(null);
+
+      TransformingSetSupplier<String, String> supplier = new TransformingSetSupplier<String, String>(Suppliers
+               .<Iterable<String>> ofInstance(ofNull), Functions.forMap(ImmutableMap.of("foo", "bar")));
+      assertEquals(supplier.get(), ImmutableSet.<String> of());
+   }
+
+   @SuppressWarnings("unchecked")
+   @Test
+   public void testNullsNotReturnedFromFunction() {
+      TransformingSetSupplier<String, String> supplier = new TransformingSetSupplier<String, String>(Suppliers
+               .<Iterable<String>> ofInstance(ImmutableSet.of("foo")), (Function) Functions.constant(null));
+      assertEquals(supplier.get(), ImmutableSet.<String> of());
+   }
+
+}