Add search by labels.

src/main/java/org/zendesk/client/v2/Zendesk.java

@@ -403,6 +403,16 @@ public Iterable<Article> getArticleFromSearch(String searchTerm, Long sectionId)
                 .set("query", searchTerm).set("section", sectionId), handleList(Article.class, "results"));
     }
 
+    public Iterable<Article> getArticlesFromAnyLabels(List<String> labels) {
+        return new PagedIterable<>(tmpl("/help_center/articles/search.json{?label_names}").set("label_names", labels),
+              handleList(Article.class, "results"));
+    }
+
+    public Iterable<Article> getArticlesFromAllLabels(List<String> labels) {
+        return new PagedIterable<>(tmpl("/help_center/en-us/articles.json{?label_names}").set("label_names", labels),
+              handleList(Article.class, "articles"));
+    }
+
     public List<ArticleAttachments> getAttachmentsFromArticle(Long articleID) {
         return complete(submit(req("GET", tmpl("/help_center/articles/{id}/attachments.json").set("id", articleID)),
                 handleArticleAttachmentsList("article_attachments")));

src/test/java/org/zendesk/client/v2/RealSmokeTest.java

@@ -1,5 +1,6 @@
 package org.zendesk.client.v2;
 
+import org.hamcrest.core.IsCollectionContaining;
 import org.junit.After;
 import org.junit.BeforeClass;
 import org.junit.Ignore;
@@ -38,8 +39,10 @@
 import java.util.Collections;
 import java.util.Date;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Properties;
+import java.util.Set;
 import java.util.UUID;
 
 import static org.hamcrest.CoreMatchers.anyOf;
@@ -824,6 +827,47 @@ public void getArticles() throws Exception {
         }
     }
 
+    @Test
+    public void getArticlesFromAnyLabels() throws Exception {
+        createClientWithTokenOrPassword();
+        /*
+         Given 3 articles
+            Article 1 with title "SomeLabelOne" and label "SomeLabelA"
+            Article 2 with title "SomeLabelTwo" and labels "SomeLabelB" and "SomeLabelC"
+            Article 3 with title "SomeLabelThree" and label "SomeLabelD"
+         When a search by labels "SomeLabelA", "SomeLabelB"
+         Then we get Article 1 and Article 2 but not Article 3
+            because Article 1 and 2 have at least one of the labels, Article 3 has none
+         */
+        Iterable<Article> result = instance.getArticlesFromAnyLabels(Arrays.asList("SomeLabelA", "SomeLabelB"));
+        Set<String> actualTitles = extractTitles(result);
+        assertThat(actualTitles.size(), is(2));
+        assertThat(actualTitles, IsCollectionContaining.hasItems("SomeLabelOne", "SomeLabelTwo"));
+    }
+
+    @Test
+    public void getArticlesFromAllLabels() throws Exception {
+        createClientWithTokenOrPassword();
+        /*
+         Given 2 articles
+            Article 1 with title "AllLabelOne" and label "AllLabelA"
+            Article 2 with title "AllLabelTwo" and labels "AllLabelA" and "AllLabelB"
+         When a search by labels "AllLabelA", "AllLabelB"
+         Then we get Article 2 but not Article 1
+            because Article 2 has both labels and Article 1 has only one
+         */
+        Iterable<Article> result = instance.getArticlesFromAllLabels(Arrays.asList("AllLabelA", "AllLabelB"));
+        Set<String> actualTitles = extractTitles(result);
+        assertThat(actualTitles.size(), is(1));
+        assertThat(actualTitles, IsCollectionContaining.hasItems("AllLabelTwo"));
+    }
+
+    private Set<String> extractTitles(Iterable<Article> iter) {
+        Set<String> result = new HashSet<>();
+        iter.forEach(article -> result.add(article.getTitle()));
+        return result;
+    }
+
     @Test
     public void getArticleSubscriptions() throws Exception {
         createClientWithTokenOrPassword();