fix: detect changes to the root package in single-package repos

.bumpy/single-package-changed-detection.md

@@ -0,0 +1,5 @@
+---
+'@varlock/bumpy': patch
+---
+
+Fix changed-package detection in single-package (non-monorepo) repos. Both `findChangedPackages` (used by `check`/`ci check`) and `mapFilesToPackages` (used by `generate`) matched changed files against `pkgRelDir + '/'`, but for the root package the relative dir is empty, so the check became `file.startsWith('/')` — always false for git's relative paths. As a result `ci check` always reported "No managed packages have changed" (never requiring a bump file or posting a PR comment) and `generate` never attributed commits to the root package. The root package (empty relative dir) now treats every changed file as belonging to it, while still honoring `changedFilePatterns`.

packages/bumpy/src/commands/check.ts

@@ -258,14 +258,22 @@ export async function findChangedPackages(
 
   for (const [name, pkg] of packages) {
     const pkgRelDir = relative(rootDir, pkg.dir);
-    if (!pkgRelDir) continue; // root-level package: not flagged by file globs (unchanged behavior)
+    // Root package (single-package repo) has an empty relative dir — every changed
+    // file belongs to it and is matched directly. Other packages only own files
+    // under their own directory.
+    const isRoot = pkgRelDir === '';
     const prefix = `${pkgRelDir}/`;
     const matcher = matchers.get(name)!;
 
     let pkgJsonOnlyTrigger = false;
     for (const file of changedFiles) {
-      if (!file.startsWith(prefix)) continue;
-      const relToPackage = file.slice(prefix.length);
+      let relToPackage: string;
+      if (isRoot) {
+        relToPackage = file;
+      } else {
+        if (!file.startsWith(prefix)) continue;
+        relToPackage = file.slice(prefix.length);
+      }
       if (!matcher(relToPackage)) continue;
       if (relToPackage === 'package.json') {
         pkgJsonOnlyTrigger = true; // defer — refine by inspecting which fields changed
@@ -328,7 +336,7 @@ async function packageJsonAffectsRelease(
   ignoredFields: string[],
   releaseTriggeringDevDeps?: string[],
 ): Promise<boolean> {
-  const relPath = `${pkgRelDir}/package.json`;
+  const relPath = pkgRelDir ? `${pkgRelDir}/package.json` : 'package.json';
   const beforeRaw = readFileAtRef(rootDir, baseRef, relPath);
   if (beforeRaw == null) return true; // not present at base (new package) → release-affecting
 

packages/bumpy/src/commands/generate.ts

@@ -191,12 +191,18 @@ function mergeRelease(
 }
 
 /** Map file paths to package names based on directory containment */
-function mapFilesToPackages(files: string[], packages: Map<string, WorkspacePackage>, rootDir: string): string[] {
+export function mapFilesToPackages(
+  files: string[],
+  packages: Map<string, WorkspacePackage>,
+  rootDir: string,
+): string[] {
   const matched = new Set<string>();
   for (const file of files) {
     for (const [name, pkg] of packages) {
       const pkgRelDir = relative(rootDir, pkg.dir);
-      if (file.startsWith(pkgRelDir + '/')) {
+      // Root package (single-package repo) has an empty relative dir, so every
+      // file belongs to it. Otherwise the file must live under the package dir.
+      if (pkgRelDir === '' || file.startsWith(pkgRelDir + '/')) {
         matched.add(name);
       }
     }

packages/bumpy/test/core/check.test.ts

@@ -2,7 +2,8 @@ import { test, expect, describe, beforeEach, afterEach } from 'bun:test';
 import { resolve } from 'node:path';
 import { mkdir, writeFile, rm } from 'node:fs/promises';
 import { extractBumpFileIdsFromChangedFiles, filterBranchBumpFiles } from '../../src/core/bump-file.ts';
-import { makeBumpFile } from '../helpers.ts';
+import { findChangedPackages } from '../../src/commands/check.ts';
+import { makeBumpFile, makePkg, makeConfig } from '../helpers.ts';
 
 describe('extractBumpFileIdsFromChangedFiles', () => {
   test('extracts bump file IDs from changed files', () => {
@@ -98,3 +99,37 @@ describe('filterBranchBumpFiles', () => {
     });
   });
 });
+
+describe('findChangedPackages', () => {
+  const rootDir = '/repo';
+
+  test('detects the root package in a single-package repo', async () => {
+    // Single-package repo: the only package IS the root, so pkg.dir === rootDir
+    // and its relative dir is empty. Every changed file belongs to it.
+    const packages = new Map([['fledgling', makePkg('fledgling', '1.0.0', { dir: rootDir })]]);
+    const changed = ['src/cli.ts', 'package.json', 'src/wizard.ts'];
+
+    const result = await findChangedPackages(changed, packages, rootDir, makeConfig());
+    expect(result).toEqual(['fledgling']);
+  });
+
+  test('respects changedFilePatterns for the root package', async () => {
+    const packages = new Map([['fledgling', makePkg('fledgling', '1.0.0', { dir: rootDir })]]);
+    const config = makeConfig({ changedFilePatterns: ['src/**'] });
+
+    expect(await findChangedPackages(['src/cli.ts'], packages, rootDir, config)).toEqual(['fledgling']);
+    // A file outside the pattern shouldn't count as a change
+    expect(await findChangedPackages(['README.md'], packages, rootDir, config)).toEqual([]);
+  });
+
+  test('still scopes changes by directory in a monorepo', async () => {
+    const packages = new Map([
+      ['pkg-a', makePkg('pkg-a', '1.0.0', { dir: `${rootDir}/packages/pkg-a` })],
+      ['pkg-b', makePkg('pkg-b', '1.0.0', { dir: `${rootDir}/packages/pkg-b` })],
+    ]);
+    const changed = ['packages/pkg-a/src/index.ts'];
+
+    const result = await findChangedPackages(changed, packages, rootDir, makeConfig());
+    expect(result).toEqual(['pkg-a']);
+  });
+});

packages/bumpy/test/core/generate.test.ts

@@ -0,0 +1,22 @@
+import { test, expect, describe } from 'bun:test';
+import { mapFilesToPackages } from '../../src/commands/generate.ts';
+import { makePkg } from '../helpers.ts';
+
+describe('mapFilesToPackages', () => {
+  const rootDir = '/repo';
+
+  test('attributes every file to the root package in a single-package repo', () => {
+    const packages = new Map([['fledgling', makePkg('fledgling', '1.0.0', { dir: rootDir })]]);
+    const result = mapFilesToPackages(['src/cli.ts', 'package.json'], packages, rootDir);
+    expect(result).toEqual(['fledgling']);
+  });
+
+  test('scopes files by directory in a monorepo', () => {
+    const packages = new Map([
+      ['pkg-a', makePkg('pkg-a', '1.0.0', { dir: `${rootDir}/packages/pkg-a` })],
+      ['pkg-b', makePkg('pkg-b', '1.0.0', { dir: `${rootDir}/packages/pkg-b` })],
+    ]);
+    const result = mapFilesToPackages(['packages/pkg-b/src/index.ts'], packages, rootDir);
+    expect(result).toEqual(['pkg-b']);
+  });
+});