Fix pager iterator and add test.

Author: brendandburns

extended/src/main/java/io/kubernetes/client/extended/pager/Pager.java

@@ -59,7 +59,9 @@ public Pager(
    */
   @Override
   public Iterator<ApiType> iterator() {
-    return new PagerIterator();
+    PagerIterator it = new PagerIterator();
+    it.makeCall();
+    return it;
   }
 
   /** returns next list call by setting continue variable and limit */
@@ -117,37 +119,44 @@ private class PagerIterator implements Iterator<ApiType> {
      */
     @Override
     public boolean hasNext() {
+      if (listObjectCurrentPage.getItems() == null
+          || listObjectCurrentPage.getItems().size() == 0) {
+        return false;
+      }
       if (!started) {
         started = true;
         return Boolean.TRUE;
       }
       return !(continueToken == null && offsetCurrentPage >= currentPageSize);
     }
 
-    /**
-     * returns next chunk of List. size of list depends on limit set in constructor.
-     *
-     * @return the next Object
-     */
-    @Override
-    public ApiType next() {
+    protected void makeCall() {
       try {
-        if (offsetCurrentPage >= currentPageSize) {
+        call = getNextCall(limit, continueToken);
 
-          call = getNextCall(limit, continueToken);
+        listObjectCurrentPage = executeRequest(call);
+        continueToken = listObjectCurrentPage.getMetadata().getContinue();
 
-          listObjectCurrentPage = executeRequest(call);
-          continueToken = listObjectCurrentPage.getMetadata().getContinue();
-
-          offsetCurrentPage = 0;
-          currentPageSize = listObjectCurrentPage.getItems().size();
-        }
-        return (ApiType) listObjectCurrentPage.getItems().get(offsetCurrentPage++);
+        offsetCurrentPage = 0;
+        currentPageSize = listObjectCurrentPage.getItems().size();
       } catch (ApiException e) {
         throw new RuntimeException(e.getResponseBody());
       } catch (IOException e) {
         throw new RuntimeException(e);
       }
     }
+
+    /**
+     * returns next chunk of List. size of list depends on limit set in constructor.
+     *
+     * @return the next Object
+     */
+    @Override
+    public ApiType next() {
+      if (offsetCurrentPage >= currentPageSize) {
+        makeCall();
+      }
+      return (ApiType) listObjectCurrentPage.getItems().get(offsetCurrentPage++);
+    }
   }
 }

extended/src/test/java/io/kubernetes/client/extended/pager/PagerTest.java

@@ -19,7 +19,10 @@
 import static com.github.tomakehurst.wiremock.client.WireMock.stubFor;
 import static com.github.tomakehurst.wiremock.client.WireMock.urlPathEqualTo;
 import static com.github.tomakehurst.wiremock.client.WireMock.verify;
-import static org.junit.Assert.*;
+import static com.github.tomakehurst.wiremock.core.WireMockConfiguration.wireMockConfig;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.fail;
 
 import com.github.tomakehurst.wiremock.junit.WireMockRule;
 import com.google.common.io.Resources;
@@ -31,6 +34,7 @@
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Paths;
+import java.util.Iterator;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
@@ -42,6 +46,8 @@
 public class PagerTest {
 
   private ApiClient client;
+  private static final String LIST_PAGE0_FILE_PATH =
+      Resources.getResource("namespace-list-pager0.json").getPath();
   private static final String LIST_PAGE1_FILE_PATH =
       Resources.getResource("namespace-list-pager1.json").getPath();
   private static final String LIST_PAGE2_FILE_PATH =
@@ -50,12 +56,41 @@ public class PagerTest {
       Resources.getResource("status-400.json").getPath();
   private static final String STATUS_BAD_TOKEN_FILE_PATH =
       Resources.getResource("bad-token-status.json").getPath();
-  private static final int PORT = 8087;
-  @Rule public WireMockRule wireMockRule = new WireMockRule(PORT);
+  @Rule public WireMockRule wireMockRule = new WireMockRule(wireMockConfig().dynamicPort());
 
   @Before
   public void setup() throws IOException {
-    client = new ClientBuilder().setBasePath("http://localhost:" + PORT).build();
+    client = new ClientBuilder().setBasePath("http://localhost:" + wireMockRule.port()).build();
+  }
+
+  @Test
+  public void testIteratorForEmptyList() throws IOException {
+    String namespaceListPage0Str = new String(Files.readAllBytes(Paths.get(LIST_PAGE0_FILE_PATH)));
+    CoreV1Api api = new CoreV1Api(client);
+
+    stubFor(
+        get(urlPathEqualTo("/api/v1/namespaces"))
+            .willReturn(
+                aResponse()
+                    .withStatus(200)
+                    .withHeader("Content-Type", "application/json")
+                    .withBody(namespaceListPage0Str)));
+
+    Pager<V1Namespace, V1NamespaceList> pager =
+        new Pager<V1Namespace, V1NamespaceList>(
+            (Pager.PagerParams param) -> {
+              try {
+                return api.listNamespaceCall(
+                    null, null, null, null, null, null, null, null, null, null);
+              } catch (Exception e) {
+                throw new RuntimeException(e);
+              }
+            },
+            client,
+            1,
+            V1NamespaceList.class);
+    Iterator<V1Namespace> it = pager.iterator();
+    assertFalse("Iterator should be empty.", it.hasNext());
   }
 
   @Test

extended/src/test/resources/namespace-list-pager0.json

@@ -0,0 +1,9 @@
+{
+    "kind": "NamespaceList",
+    "apiVersion": "v1",
+    "metadata": {
+      "selfLink": "/api/v1/namespaces",
+      "resourceVersion": "61027"
+    },
+    "items": []
+}