update branch & change base on PRs

src/main/java/org/kohsuke/github/GHPullRequest.java

@@ -37,6 +37,7 @@
 
 import javax.annotation.CheckForNull;
 
+import static org.kohsuke.github.Previews.LYDIAN;
 import static org.kohsuke.github.Previews.SHADOW_CAT;
 
 /**
@@ -565,6 +566,41 @@ public void requestTeamReviewers(List<GHTeam> teams) throws IOException {
                 .send();
     }
 
+    /**
+     * Set the base branch on the pull request
+     *
+     * @param newBaseBranch
+     *            the name of the new base branch
+     * @throws IOException
+     *             the io exception
+     * @return the updated pull request
+     */
+    public GHPullRequest setBaseBranch(String newBaseBranch) throws IOException {
+        return root.createRequest()
+                .method("PATCH")
+                .with("base", newBaseBranch)
+                .withUrlPath(getApiRoute())
+                .fetch(GHPullRequest.class)
+                .wrapUp(root);
+    }
+
+    /**
+     * Updates the branch. The same as pressing the button in the web GUI.
+     *
+     * @throws IOException
+     *             the io exception
+     */
+    @Preview
+    @Deprecated
+    public void updateBranch() throws IOException {
+        root.createRequest()
+                .withPreview(LYDIAN)
+                .method("PUT")
+                .with("expected_head_sha", head.getSha())
+                .withUrlPath(getApiRoute() + "/update-branch")
+                .send();
+    }
+
     /**
      * Merge this pull request.
      * <p>

src/main/java/org/kohsuke/github/Previews.java

@@ -44,6 +44,13 @@ class Previews {
      */
     static final String INERTIA = "application/vnd.github.inertia-preview+json";
 
+    /**
+     * Update a pull request branch
+     *
+     * @see <a href="https://developer.github.com/v3/previews/#update-a-pull-request-branch">GitHub API Previews</a>
+     */
+    static final String LYDIAN = "application/vnd.github.lydian-preview+json";
+
     /**
      * Require multiple approving reviews
      *

src/test/java/org/kohsuke/github/GHPullRequestTest.java

@@ -211,6 +211,106 @@ public void mergeCommitSHA() throws Exception {
         fail();
     }
 
+    @Test
+    public void setBaseBranch() throws Exception {
+        String prName = "testSetBaseBranch";
+        String originalBaseBranch = "master";
+        String newBaseBranch = "gh-pages";
+
+        GHPullRequest pullRequest = getRepository().createPullRequest(prName, "test/stable", "master", "## test");
+
+        assertEquals("Pull request base branch is supposed to be " + originalBaseBranch,
+                originalBaseBranch,
+                pullRequest.getBase().getRef());
+
+        GHPullRequest responsePullRequest = pullRequest.setBaseBranch(newBaseBranch);
+
+        assertEquals("Pull request base branch is supposed to be " + newBaseBranch,
+                newBaseBranch,
+                responsePullRequest.getBase().getRef());
+    }
+
+    @Test
+    public void setBaseBranchNonExisting() throws Exception {
+        String prName = "testSetBaseBranchNonExisting";
+        String originalBaseBranch = "master";
+        String newBaseBranch = "non-existing";
+
+        GHPullRequest pullRequest = getRepository().createPullRequest(prName, "test/stable", "master", "## test");
+
+        assertEquals("Pull request base branch is supposed to be " + originalBaseBranch,
+                originalBaseBranch,
+                pullRequest.getBase().getRef());
+
+        try {
+            pullRequest.setBaseBranch(newBaseBranch);
+        } catch (HttpException e) {
+            assertThat(e, instanceOf(HttpException.class));
+            assertThat(e.toString(), containsString("Proposed base branch 'non-existing' was not found"));
+        }
+
+        pullRequest.close();
+    }
+
+    @Test
+    public void updateOutdatedBranchesUnexpectedHead() throws Exception {
+        String prName = "testUpdateOutdatedBranches";
+        String outdatedRefName = "refs/heads/outdated";
+        GHRepository repository = gitHub.getOrganization("hub4j-test-org").getRepository("updateOutdatedBranches");
+
+        GHRef outdatedRef = repository.getRef(outdatedRefName);
+        outdatedRef.updateTo("6440189369f9f33b2366556a94dbc26f2cfdd969", true);
+
+        GHPullRequest outdatedPullRequest = repository.createPullRequest(prName, "outdated", "master", "## test");
+
+        do {
+            Thread.sleep(5000);
+            outdatedPullRequest.refresh();
+        } while (outdatedPullRequest.getMergeableState().equalsIgnoreCase("unknown"));
+
+        assertEquals("Pull request is supposed to be not up to date",
+                "behind",
+                outdatedPullRequest.getMergeableState());
+
+        outdatedRef.updateTo("f567328eb81270487864963b7d7446953353f2b5", true);
+
+        try {
+            outdatedPullRequest.updateBranch();
+        } catch (HttpException e) {
+            assertThat(e, instanceOf(HttpException.class));
+            assertThat(e.toString(), containsString("expected head sha didn’t match current head ref."));
+        }
+
+        outdatedPullRequest.close();
+    }
+
+    @Test
+    public void updateOutdatedBranches() throws Exception {
+        String prName = "testUpdateOutdatedBranches";
+        String outdatedRefName = "refs/heads/outdated";
+        GHRepository repository = gitHub.getOrganization("hub4j-test-org").getRepository("updateOutdatedBranches");
+
+        repository.getRef(outdatedRefName).updateTo("6440189369f9f33b2366556a94dbc26f2cfdd969", true);
+
+        GHPullRequest outdatedPullRequest = repository.createPullRequest(prName, "outdated", "master", "## test");
+
+        do {
+            Thread.sleep(5000);
+            outdatedPullRequest.refresh();
+        } while (outdatedPullRequest.getMergeableState().equalsIgnoreCase("unknown"));
+
+        assertEquals("Pull request is supposed to be not up to date",
+                "behind",
+                outdatedPullRequest.getMergeableState());
+
+        outdatedPullRequest.updateBranch();
+        outdatedPullRequest.refresh();
+
+        assertNotEquals("Pull request is supposed to be up to date", "behind", outdatedPullRequest.getMergeableState());
+
+        outdatedPullRequest.close();
+    }
+
     @Test
     public void squashMerge() throws Exception {
         String name = "squashMerge";

src/test/resources/org/kohsuke/github/GHPullRequestTest/wiremock/setBaseBranch/__files/orgs_hub4j-test-org-1.json

@@ -0,0 +1,47 @@
+{
+  "login": "hub4j-test-org",
+  "id": 7544739,
+  "node_id": "MDEyOk9yZ2FuaXphdGlvbjc1NDQ3Mzk=",
+  "url": "https://api.github.com/orgs/hub4j-test-org",
+  "repos_url": "https://api.github.com/orgs/hub4j-test-org/repos",
+  "events_url": "https://api.github.com/orgs/hub4j-test-org/events",
+  "hooks_url": "https://api.github.com/orgs/hub4j-test-org/hooks",
+  "issues_url": "https://api.github.com/orgs/hub4j-test-org/issues",
+  "members_url": "https://api.github.com/orgs/hub4j-test-org/members{/member}",
+  "public_members_url": "https://api.github.com/orgs/hub4j-test-org/public_members{/member}",
+  "avatar_url": "https://avatars3.githubusercontent.com/u/7544739?v=4",
+  "description": "Hub4j Test Org Description (this could be null or blank too)",
+  "name": "Hub4j Test Org Name (this could be null or blank too)",
+  "company": null,
+  "blog": "https://hub4j.url.io/could/be/null",
+  "location": "Hub4j Test Org Location (this could be null or blank too)",
+  "email": "hub4jtestorgemail@could.be.null.com",
+  "twitter_username": null,
+  "is_verified": false,
+  "has_organization_projects": true,
+  "has_repository_projects": true,
+  "public_repos": 13,
+  "public_gists": 0,
+  "followers": 0,
+  "following": 0,
+  "html_url": "https://github.com/hub4j-test-org",
+  "created_at": "2014-05-10T19:39:11Z",
+  "updated_at": "2020-06-04T05:56:10Z",
+  "type": "Organization",
+  "total_private_repos": 0,
+  "owned_private_repos": 0,
+  "private_gists": 0,
+  "disk_usage": 149,
+  "collaborators": 0,
+  "billing_email": "kk@kohsuke.org",
+  "default_repository_permission": "none",
+  "members_can_create_repositories": false,
+  "two_factor_requirement_enabled": false,
+  "plan": {
+    "name": "free",
+    "space": 976562499,
+    "private_repos": 10000,
+    "filled_seats": 18,
+    "seats": 3
+  }
+}