This closes #2120

apache · Mar 22, 2017 · 2d9bf27 · 2d9bf27
2 parents e1dc7a8 + f1badfd
commit 2d9bf27
Showing 1 changed file with 15 additions and 0 deletions.
diff --git a/sdks/java/core/src/test/java/org/apache/beam/sdk/transforms/FlattenTest.java b/sdks/java/core/src/test/java/org/apache/beam/sdk/transforms/FlattenTest.java
@@ -22,6 +22,9 @@
 import static org.apache.beam.sdk.TestUtils.LINES_ARRAY;
 import static org.apache.beam.sdk.TestUtils.NO_LINES;
 import static org.apache.beam.sdk.TestUtils.NO_LINES_ARRAY;
+import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.not;
+import static org.junit.Assert.assertThat;
 
 import com.google.common.collect.ImmutableSet;
 import java.io.Serializable;
@@ -93,6 +96,18 @@ public void testFlattenPCollections() {
     p.run();
   }
 
+  @Test
+  @Category(RunnableOnService.class)
+  public void testFlattenPCollectionsSingletonList() {
+    PCollection<String> input = p.apply(Create.of(LINES));
+    PCollection<String> output = PCollectionList.of(input).apply(Flatten.<String>pCollections());
+
+    assertThat(output, not(equalTo(input)));
+
+    PAssert.that(output).containsInAnyOrder(LINES);
+    p.run();
+  }
+
   @Test
   @Category(RunnableOnService.class)
   public void testFlattenPCollectionsThenParDo() {