fix: Use strategies for workspace plugins.

src/plugins/cargo-workspace.ts

@@ -233,10 +233,10 @@ export class CargoWorkspace extends WorkspacePlugin<CrateInfo> {
     return existingCandidate;
   }
 
-  protected newCandidate(
+  protected async newCandidate(
     pkg: CrateInfo,
     updatedVersions: VersionsMap
-  ): CandidateReleasePullRequest {
+  ): Promise<CandidateReleasePullRequest> {
     const version = updatedVersions.get(pkg.name);
     if (!version) {
       throw new Error(`Didn't find updated version for ${pkg.name}`);

src/plugins/maven-workspace.ts

@@ -394,10 +394,10 @@ export class MavenWorkspace extends WorkspacePlugin<MavenArtifact> {
     }
     return existingCandidate;
   }
-  protected newCandidate(
+  protected async newCandidate(
     artifact: MavenArtifact,
     updatedVersions: VersionsMap
-  ): CandidateReleasePullRequest {
+  ): Promise<CandidateReleasePullRequest> {
     const version = updatedVersions.get(artifact.name);
     if (!version) {
       throw new Error(`Didn't find updated version for ${artifact.name}`);

src/plugins/node-workspace.ts

@@ -36,6 +36,9 @@ import {
   addPath,
 } from './workspace';
 import {PatchVersionUpdate} from '../versioning-strategy';
+import {Strategy} from '../strategy';
+import {Commit} from '../commit';
+import {Release} from '../release';
 
 class Package extends LernaPackage {
   constructor(
@@ -69,6 +72,10 @@ interface NodeWorkspaceOptions extends WorkspacePluginOptions {
 export class NodeWorkspace extends WorkspacePlugin<Package> {
   private alwaysLinkLocal: boolean;
   private packageGraph?: PackageGraph;
+
+  private strategiesByPath: Record<string, Strategy> = {};
+  private releasesByPath: Record<string, Release> = {};
+
   constructor(
     github: GitHub,
     targetBranch: string,
@@ -232,10 +239,10 @@ export class NodeWorkspace extends WorkspacePlugin<Package> {
     }
     return existingCandidate;
   }
-  protected newCandidate(
+  protected async newCandidate(
     pkg: Package,
     updatedVersions: VersionsMap
-  ): CandidateReleasePullRequest {
+  ): Promise<CandidateReleasePullRequest> {
     const graphPackage = this.packageGraph?.get(pkg.name);
     if (!graphPackage) {
       throw new Error(`Could not find graph package for ${pkg.name}`);
@@ -271,20 +278,31 @@ export class NodeWorkspace extends WorkspacePlugin<Package> {
     );
     const packageJson = updatedPackage.toJSON() as PackageJson;
     const version = Version.parse(packageJson.version);
+
+    const strategy = this.strategiesByPath[updatedPackage.location];
+    const latestRelease = this.releasesByPath[updatedPackage.location];
+
+    const basePullRequest = strategy
+      ? await strategy.buildReleasePullRequest([], latestRelease, false, [], {
+          newVersion: version,
+        })
+      : undefined;
+
     const pullRequest: ReleasePullRequest = {
       title: PullRequestTitle.ofTargetBranch(this.targetBranch),
       body: new PullRequestBody([
         {
           component: updatedPackage.name,
           version,
           notes: appendDependenciesSectionToChangelog(
-            '',
+            basePullRequest?.body.notes() ?? '',
             dependencyNotes,
             this.logger
           ),
         },
       ]),
       updates: [
+        ...(basePullRequest ? basePullRequest?.updates : []),
         {
           path: addPath(updatedPackage.location, 'package.json'),
           createIfMissing: false,
@@ -297,16 +315,17 @@ export class NodeWorkspace extends WorkspacePlugin<Package> {
           createIfMissing: false,
           updater: new Changelog({
             version,
-            changelogEntry: appendDependenciesSectionToChangelog(
-              '',
-              dependencyNotes,
-              this.logger
-            ),
+            versionHeaderRegex: `\n###? v?[${version
+              .toString()
+              .replace('.', '.')}]`,
+            changelogEntry: dependencyNotes,
           }),
         },
       ],
       labels: [],
-      headRefName: BranchName.ofTargetBranch(this.targetBranch).toString(),
+      headRefName:
+        basePullRequest?.headRefName ??
+        BranchName.ofTargetBranch(this.targetBranch).toString(),
       version,
       draft: false,
     };
@@ -375,6 +394,18 @@ export class NodeWorkspace extends WorkspacePlugin<Package> {
       ...(packageJson.optionalDependencies ?? {}),
     };
   }
+
+  async preconfigure(
+    strategiesByPath: Record<string, Strategy>,
+    _commitsByPath: Record<string, Commit[]>,
+    _releasesByPath: Record<string, Release>
+  ): Promise<Record<string, Strategy>> {
+    // Using preconfigure to siphon releases and strategies.
+    this.strategiesByPath = strategiesByPath;
+    this.releasesByPath = _releasesByPath;
+
+    return strategiesByPath;
+  }
 }
 
 enum SUPPORTED_RANGE_PREFIXES {

src/plugins/workspace.ts

@@ -154,7 +154,7 @@ export abstract class WorkspacePlugin<T> extends ManifestPlugin {
             pkg
           )}`
         );
-        const newCandidate = this.newCandidate(pkg, updatedVersions);
+        const newCandidate = await this.newCandidate(pkg, updatedVersions);
         if (newCandidatePaths.has(newCandidate.path)) {
           this.logger.info(
             `Already created new candidate for path: ${newCandidate.path}`
@@ -320,7 +320,7 @@ export abstract class WorkspacePlugin<T> extends ManifestPlugin {
   protected abstract newCandidate(
     pkg: T,
     updatedVersions: VersionsMap
-  ): CandidateReleasePullRequest;
+  ): Promise<CandidateReleasePullRequest>;
 
   /**
    * Collect all packages being managed in this workspace.

src/strategies/base.ts

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-import {Strategy, BuildReleaseOptions} from '../strategy';
+import {Strategy, BuildReleaseOptions, BumpReleaseOptions} from '../strategy';
 import {GitHub} from '../github';
 import {VersioningStrategy} from '../versioning-strategy';
 import {Repository} from '../repository';
@@ -254,19 +254,19 @@ export abstract class BaseStrategy implements Strategy {
     commits: ConventionalCommit[],
     latestRelease?: Release,
     draft?: boolean,
-    labels: string[] = []
+    labels: string[] = [],
+    bumpOnlyOptions?: BumpReleaseOptions
   ): Promise<ReleasePullRequest | undefined> {
     const conventionalCommits = await this.postProcessCommits(commits);
     this.logger.info(`Considering: ${conventionalCommits.length} commits`);
-    if (conventionalCommits.length === 0) {
+    if (!bumpOnlyOptions && conventionalCommits.length === 0) {
       this.logger.info(`No commits for path: ${this.path}, skipping`);
       return undefined;
     }
 
-    const newVersion = await this.buildNewVersion(
-      conventionalCommits,
-      latestRelease
-    );
+    const newVersion =
+      bumpOnlyOptions?.newVersion ??
+      (await this.buildNewVersion(conventionalCommits, latestRelease));
     const versionsMap = await this.updateVersionsMap(
       await this.buildVersionsMap(conventionalCommits),
       conventionalCommits,
@@ -302,7 +302,7 @@ export abstract class BaseStrategy implements Strategy {
       latestRelease,
       commits
     );
-    if (this.changelogEmpty(releaseNotesBody)) {
+    if (!bumpOnlyOptions && this.changelogEmpty(releaseNotesBody)) {
       this.logger.info(
         `No user facing commits found since ${
           latestRelease ? latestRelease.sha : 'beginning of time'

src/strategies/java.ts

@@ -30,6 +30,7 @@ import {DEFAULT_SNAPSHOT_LABELS} from '../manifest';
 import {JavaReleased} from '../updaters/java/java-released';
 import {mergeUpdates} from '../updaters/composite';
 import {logger as defaultLogger} from '../util/logger';
+import {BumpReleaseOptions} from '../strategy';
 
 const CHANGELOG_SECTIONS = [
   {type: 'feat', section: 'Features'},
@@ -77,7 +78,8 @@ export class Java extends BaseStrategy {
     commits: ConventionalCommit[],
     latestRelease?: Release,
     draft?: boolean,
-    labels: string[] = []
+    labels: string[] = [],
+    _bumpOnlyOptions?: BumpReleaseOptions
   ): Promise<ReleasePullRequest | undefined> {
     if (await this.needsSnapshot(commits, latestRelease)) {
       this.logger.info('Repository needs a snapshot bump.');

src/strategies/php-yoshi.ts

@@ -29,6 +29,7 @@ import {BranchName} from '../util/branch-name';
 import {PullRequestBody} from '../util/pull-request-body';
 import {GitHubFileContents} from '@google-automations/git-file-utils';
 import {FileNotFoundError} from '../errors';
+import {BumpReleaseOptions} from '../strategy';
 
 const CHANGELOG_SECTIONS = [
   {type: 'feat', section: 'Features'},
@@ -68,12 +69,13 @@ export class PHPYoshi extends BaseStrategy {
     commits: Commit[],
     latestRelease?: Release,
     draft?: boolean,
-    labels: string[] = []
+    labels: string[] = [],
+    bumpOnlyOptions?: BumpReleaseOptions
   ): Promise<ReleasePullRequest | undefined> {
     const conventionalCommits = await this.postProcessCommits(
       parseConventionalCommits(commits, this.logger)
     );
-    if (conventionalCommits.length === 0) {
+    if (!bumpOnlyOptions && conventionalCommits.length === 0) {
       this.logger.info(`No commits for path: ${this.path}, skipping`);
       return undefined;
     }

src/strategy.ts

@@ -24,6 +24,10 @@ export interface BuildReleaseOptions {
   groupPullRequestTitlePattern?: string;
 }
 
+export interface BumpReleaseOptions {
+  newVersion: Version;
+}
+
 /**
  * A strategy is responsible for determining which files are
  * necessary to update in a release pull request.
@@ -47,7 +51,8 @@ export interface Strategy {
     commits: Commit[],
     latestRelease?: Release,
     draft?: boolean,
-    labels?: string[]
+    labels?: string[],
+    bumpOnlyOptions?: BumpReleaseOptions
   ): Promise<ReleasePullRequest | undefined>;
 
   /**