Added Page and Stream methods for getDiff() (#497)

src/main/java/org/gitlab4j/api/CommitsApi.java

@@ -537,8 +537,46 @@ public class CommitsApi extends AbstractApi {
      * @throws GitLabApiException GitLabApiException if any exception occurs during execution
      */
     public List<Diff> getDiff(Object projectIdOrPath, String sha) throws GitLabApiException {
-        Response response = get(Response.Status.OK, null, "projects", getProjectIdOrPath(projectIdOrPath), "repository", "commits", sha, "diff");
-        return (response.readEntity(new GenericType<List<Diff>>() {}));
+        return (getDiff(projectIdOrPath, sha, getDefaultPerPage()).all());
+    }
+
+    /**
+      * Get the Pager of diffs of a commit in a project.
+     *
+     * <pre><code>GitLab Endpoint: GET /projects/:id/repository/commits/:sha/diff</code></pre>
+     *
+     * @param projectIdOrPath the project in the form of an Integer(ID), String(path), or Project instance
+     * @param sha a commit hash or name of a branch or tag
+     * @param itemsPerPage the number of Diff instances that will be fetched per page
+     * @return a Pager of Diff instances for the specified project ID/sha pair
+     * @throws GitLabApiException GitLabApiException if any exception occurs during execution
+     */
+    public Pager<Diff> getDiff(Object projectIdOrPath, String sha, int itemsPerPage) throws GitLabApiException {
+
+        if (projectIdOrPath == null) {
+            throw new RuntimeException("projectIdOrPath cannot be null");
+        }
+
+        if (sha == null || sha.trim().isEmpty()) {
+            throw new RuntimeException("sha cannot be null");
+        }
+
+        return (new Pager<Diff>(this, Diff.class, itemsPerPage, null,
+            "projects", getProjectIdOrPath(projectIdOrPath), "repository", "commits", sha, "diff"));
+    }
+
+    /**
+      * Get the Diff of diffs of a commit in a project.
+     *
+     * <pre><code>GitLab Endpoint: GET /projects/:id/repository/commits/:sha/diff</code></pre>
+     *
+     * @param projectIdOrPath the project in the form of an Integer(ID), String(path), or Project instance
+     * @param sha a commit hash or name of a branch or tag
+     * @return a Stream of Diff instances for the specified project ID/sha pair
+     * @throws GitLabApiException GitLabApiException if any exception occurs during execution
+     */
+    public Stream<Diff> getDiffStream(Object projectIdOrPath, String sha) throws GitLabApiException {
+        return (getDiff(projectIdOrPath, sha, getDefaultPerPage()).stream());
     }
 
     /**

src/test/java/org/gitlab4j/api/TestCommitsApi.java

@@ -13,6 +13,7 @@ import java.util.Arrays;
 import java.util.Date;
 import java.util.List;
 import java.util.Optional;
+import java.util.stream.Stream;
 
 import javax.ws.rs.core.Response;
 import org.gitlab4j.api.models.Branch;
@@ -95,6 +96,18 @@ public class TestCommitsApi extends AbstractIntegrationTest {
         assertTrue(diffs.size() > 0);
     }
 
+    @Test
+    public void testDiffStream() throws GitLabApiException {
+
+        assertNotNull(testProject);
+
+        List<Commit> commits = gitLabApi.getCommitsApi().getCommits(testProject.getId());
+        assertTrue(commits.size() > 0);
+
+        Stream<Diff> diffs = gitLabApi.getCommitsApi().getDiffStream(testProject.getId(), commits.get(0).getId());
+        assertTrue(diffs.count() > 0);
+    }
+
     @Test
     public void testComments() throws GitLabApiException, ParseException {