fix(go): Release is not idempotent to existing tags

src/help/git.ts

@@ -57,9 +57,18 @@ export function init() {
  * Cerate a tag.
  *
  * @param name tag name.
+ * @returns true if the tag was created, false if it already exists.
  */
-export function tag(name: string) {
-  shell.run(`git tag -a ${name} -m ${name}`);
+export function tag(name: string): boolean {
+  try {
+    shell.run(`git tag -a ${name} -m ${name}`, { capture: true });
+    return true;
+  } catch (e) {
+    if (e.message.includes('already exists')) {
+      return false;
+    }
+    throw e;
+  }
 }
 
 /**

src/help/shell.ts

@@ -36,22 +36,27 @@ export interface RunOptions {
  */
 export function run(command: string, options: RunOptions = {}): string {
   const shsplit = shlex.split(command);
-  const pipe = options.capture ?? false;
+  const pipeOrInherit = (options.capture ?? false) ? 'pipe': 'inherit';
   const result = child.spawnSync(shsplit[0], shsplit.slice(1), {
-    stdio: ['ignore', pipe ? 'pipe' : 'inherit', process.stdout],
+    stdio: ['ignore', pipeOrInherit, pipeOrInherit],
     cwd: options.cwd,
     shell: options.shell,
   });
   if (result.error) {
     throw result.error;
   }
-  // we always redirect stderr to stdout so its ok to take stdout.
-  // but when we don't pipe, we don't have the output.
-  const message = result.stdout?.toString() ?? `Command failed: ${command}`;
+
+  const stdout = result.stdout?.toString();
+  const stderr = result.stderr?.toString();
+
   if (result.status !== 0) {
+    const message = `
+    Command failed: ${command}.
+      Output: ${stdout}
+      Error:${stderr}`;
     throw new Error(message);
   }
-  return message;
+  return stdout;
 }
 
 /**

src/targets/go.ts

@@ -195,16 +195,25 @@ export class GoReleaser {
     const commitMessage = this.gitCommitMessage ?? this.buildReleaseMessage(modules);
     git.commit(commitMessage);
 
-    const tags = modules.map(m => this.buildTagName(m));
-    const refs = [...tags, this.gitBranch];
+    const tags = [];
+    for (const module of modules) {
+      const name = this.buildTagName(module);
+      const created = git.tag(name);
+      if (created) { tags.push(name); }
+    }
+
+    if (tags.length === 0) {
+      console.log('All tags already exist. Skipping release');
+      return {};
+    }
 
-    tags.forEach(t => git.tag(t));
+    const refs = [...tags, this.gitBranch];
 
     if (this.dryRun) {
       console.log('===========================================');
       console.log('            🏜️ DRY-RUN MODE 🏜️');
       console.log('===========================================');
-      refs.forEach(t => console.log(`Remote ref will update: ${t}`));
+      refs.forEach(t => console.log(`Remote ref will be updated: ${t}`));
     } else {
       refs.forEach(t => git.push(t));
     }

test/targets/go.test.ts

@@ -5,20 +5,25 @@ import * as git from '../../src/help/git';
 import * as os from '../../src/help/os';
 import * as shell from '../../src/help/shell';
 
-function initRepo(repoDir: string) {
+interface Initializers {
+  postInit?: (repoDir: string) => void;
+}
+
+function initRepo(repoDir: string, postInit?: (repoDir: string) => void) {
   const cwd = process.cwd();
   try {
     process.chdir(repoDir);
     git.init();
     git.add('.');
     git.identify('jsii-release-test', '<>');
     git.commit('Initial Commit');
+    if (postInit) { postInit(repoDir); };
   } finally {
     process.chdir(cwd);
   }
 }
 
-function createReleaser(fixture: string, props: Omit<GoReleaserProps, 'dir' | 'dryRun'> = {}) {
+function createReleaser(fixture: string, props: Omit<GoReleaserProps, 'dir' | 'dryRun'> = {}, initializers: Initializers = {}) {
 
   const fixturePath = path.join(__dirname, '..', '__fixtures__', fixture);
   const sourceDir = path.join(os.mkdtempSync(), fixture);
@@ -35,7 +40,7 @@ function createReleaser(fixture: string, props: Omit<GoReleaserProps, 'dir' | 'd
   (git as any).clone = function(_: string, targetDir: string) {
     // the cloned repo is always the original fixture.
     fs.copySync(fixturePath, targetDir, { recursive: true });
-    initRepo(targetDir);
+    initRepo(targetDir, initializers.postInit);
   };
 
   return { releaser, sourceDir };
@@ -230,3 +235,34 @@ test('throws when no major version suffix', () => {
   expect(() => releaser.release()).toThrow(/expected to end with '\/v3'/);
 
 });
+
+test('skips when all tags already exist', () => {
+
+  const { releaser, sourceDir } = createReleaser('sub-modules', {}, {
+    postInit: (_: string) => {
+      git.tag('module1/v1.1.0');
+      git.tag('module2/v1.1.0');
+    },
+  });
+
+  fs.writeFileSync(path.join(sourceDir, 'file'), 'test');
+
+  const release = releaser.release();
+  expect(release).toStrictEqual({});
+
+});
+
+test('creates missing tags only', () => {
+
+  const { releaser, sourceDir } = createReleaser('sub-modules', {}, {
+    postInit: (_: string) => {
+      git.tag('module2/v1.1.0');
+    },
+  });
+
+  fs.writeFileSync(path.join(sourceDir, 'file'), 'test');
+
+  const release = releaser.release();
+  expect(release.tags).toEqual(['module1/v1.1.0']);
+
+});