refactor: add explicit return types (#412)

README.md

@@ -37,7 +37,7 @@ CLI output also includes output size and exports for quick inspection.
 
 Create `src/index.ts`:
 
-```ts
+```js
 export const log = (...args) => {
   console.log(...args);
 };
@@ -75,7 +75,7 @@ Configuration is automatically inferred from fields in `package.json` mapped to
 
 Create `build.config.ts`:
 
-```ts
+```js
 export default {
   entries: ["./src/index"],
 };
@@ -87,7 +87,7 @@ See options [here](./src/types.ts).
 
 Example:
 
-```ts
+```js
 import { defineBuildConfig } from "unbuild";
 
 export default defineBuildConfig({
@@ -113,7 +113,7 @@ export default defineBuildConfig({
 
 Or with multiple builds you can declare an array of configs:
 
-```ts
+```js
 import { defineBuildConfig } from "unbuild";
 
 export default defineBuildConfig([

eslint.config.mjs

@@ -3,14 +3,20 @@ import unjs from "eslint-config-unjs";
 // https://github.com/unjs/eslint-config
 export default unjs({
   ignores: [
-  ".git"
-],
+    ".git",
+  ],
   rules: {
-  "unicorn/no-null": 0,
-  "unicorn/prevent-abbreviations": 0,
-  "unicorn/prefer-module": 0,
-  "unicorn/prefer-top-level-await": 0,
-  "@typescript-eslint/no-non-null-assertion": 0,
-  "@typescript-eslint/no-unused-vars": 0
-},
-});
+    "unicorn/no-null": 0,
+    "unicorn/prevent-abbreviations": 0,
+    "unicorn/prefer-module": 0,
+    "unicorn/prefer-top-level-await": 0,
+    "@typescript-eslint/no-non-null-assertion": 0,
+    "@typescript-eslint/no-unused-vars": 0,
+  },
+}, {
+  files: ["**/*.ts"],
+  rules: {
+    "@typescript-eslint/explicit-function-return-type": "error",
+    "@typescript-eslint/no-inferrable-types": "error",
+  }
+});

examples/1.zero-config/src/utils.ts

@@ -1,3 +1,3 @@
-export default function sum(a: number, b: number) {
+export default function sum(a: number, b: number): number {
   return a + b;
 }

examples/3.untyped/src/index.ts

@@ -20,6 +20,7 @@ export const config = {
     height: 10,
   },
   tags: {
-    $resolve: (val?: string[]) => ["tag1", ...(val || [])].filter(Boolean),
+    $resolve: (val?: string[]): string[] =>
+      ["tag1", ...(val || [])].filter(Boolean),
   },
 };

src/auto.ts

@@ -16,7 +16,7 @@ type InferEntriesResult = {
 export const autoPreset = definePreset(() => {
   return {
     hooks: {
-      "build:prepare"(ctx) {
+      "build:prepare"(ctx): void {
         // Disable auto if entries already provided or pkg not available
         if (!ctx.pkg || ctx.options.entries.length > 0) {
           return;
@@ -167,7 +167,7 @@ export function inferEntries(
   return { entries, cjs, dts, warnings };
 }
 
-export const getEntrypointPaths = (path: string) => {
+export const getEntrypointPaths = (path: string): string[] => {
   const segments = normalize(path).split("/");
   return segments
     .map((_, index) => segments.slice(index).join("/"))

src/build.ts

@@ -23,7 +23,7 @@ export async function build(
   rootDir: string,
   stub: boolean,
   inputConfig: BuildConfig = {},
-) {
+): Promise<void> {
   // Determine rootDir
   rootDir = resolve(process.cwd(), rootDir || ".");
 
@@ -67,7 +67,7 @@ async function _build(
   cleanedDirs: string[],
   _stubMode: boolean,
   _watchMode: boolean,
-) {
+): Promise<void> {
   // Resolve preset
   const preset = await resolvePreset(
     buildConfig.preset ||
@@ -305,7 +305,7 @@ async function _build(
     }
   }
 
-  const rPath = (p: string) =>
+  const rPath = (p: string): string =>
     relative(process.cwd(), resolve(options.outDir, p));
   for (const entry of ctx.buildEntries.filter((e) => !e.chunk)) {
     let totalBytes = entry.bytes || 0;

src/builders/copy/index.ts

@@ -7,7 +7,7 @@ import consola from "consola";
 
 const copy = fsp.cp || fsp.copyFile;
 
-export async function copyBuild(ctx: BuildContext) {
+export async function copyBuild(ctx: BuildContext): Promise<void> {
   const entries = ctx.options.entries.filter(
     (e) => e.builder === "copy",
   ) as CopyBuildEntry[];

src/builders/mkdist/index.ts

@@ -4,7 +4,7 @@ import { symlink, rmdir } from "../../utils";
 import type { MkdistBuildEntry, BuildContext } from "../../types";
 import consola from "consola";
 
-export async function mkdistBuild(ctx: BuildContext) {
+export async function mkdistBuild(ctx: BuildContext): Promise<void> {
   const entries = ctx.options.entries.filter(
     (e) => e.builder === "mkdist",
   ) as MkdistBuildEntry[];

src/builders/rollup/build.ts

@@ -10,7 +10,7 @@ import { getChunkFilename } from "./utils";
 import { rollupStub } from "./stub";
 import { rollupWatch } from "./watch";
 
-export async function rollupBuild(ctx: BuildContext) {
+export async function rollupBuild(ctx: BuildContext): Promise<void> {
   // Stub mode
   if (ctx.options.stub) {
     await rollupStub(ctx);

src/builders/rollup/config.ts

@@ -133,7 +133,7 @@ export function getRollupOptions(ctx: BuildContext): RollupOptions {
         }),
 
       ctx.options.rollup.preserveDynamicImports && {
-        renderDynamicImport() {
+        renderDynamicImport(): { left: string; right: string } {
           return { left: "import(", right: ")" };
         },
       },

src/builders/rollup/plugins/cjs.ts

@@ -28,7 +28,7 @@ const require = __cjs_mod__.createRequire(import.meta.url);
 `;
 
 // Shim __dirname, __filename and require
-function CJSToESM(code: string) {
+function CJSToESM(code: string): { code: string; map: any } | null {
   if (code.includes(CJSShim) || !CJSyntaxRe.test(code)) {
     return null;
   }

src/builders/rollup/plugins/esbuild.ts

@@ -52,7 +52,7 @@ export function esbuild(options: EsbuildOptions): Plugin {
       }
     }
   }
-  const getLoader = (id = "") => {
+  const getLoader = (id = ""): Loader | undefined => {
     return loaders[extname(id)];
   };
 
@@ -61,7 +61,7 @@ export function esbuild(options: EsbuildOptions): Plugin {
   return {
     name: "esbuild",
 
-    async transform(code, id) {
+    async transform(code, id): Promise<null | { code: string; map: any }> {
       if (!filter(id)) {
         return null;
       }
@@ -79,15 +79,18 @@ export function esbuild(options: EsbuildOptions): Plugin {
 
       printWarnings(id, result, this);
 
-      return (
-        result.code && {
-          code: result.code,
-          map: result.map || null,
-        }
-      );
+      return result.code
+        ? {
+            code: result.code,
+            map: result.map || null,
+          }
+        : null;
     },
 
-    async renderChunk(code, { fileName }) {
+    async renderChunk(
+      code,
+      { fileName },
+    ): Promise<null | undefined | { code: string; map: any }> {
       if (!options.minify) {
         return null;
       }
@@ -118,7 +121,7 @@ function printWarnings(
   id: string,
   result: TransformResult,
   plugin: PluginContext,
-) {
+): void {
   if (result.warnings) {
     for (const warning of result.warnings) {
       let message = "[esbuild]";

src/builders/rollup/plugins/raw.ts

@@ -17,7 +17,7 @@ export function rawPlugin(opts: RawLoaderOptions = {}): Plugin {
   const filter = createFilter(opts.include, opts.exclude);
   return {
     name: "unbuild-raw",
-    transform(code, id) {
+    transform(code, id): { code: string; map: any } | undefined {
       if (filter(id)) {
         return {
           code: `export default ${JSON.stringify(code)}`,

src/builders/rollup/plugins/shebang.ts

@@ -9,7 +9,7 @@ const SHEBANG_RE = /^#![^\n]*/;
 export function shebangPlugin(): Plugin {
   return {
     name: "unbuild-shebang",
-    async writeBundle(options, bundle) {
+    async writeBundle(options, bundle): Promise<void> {
       for (const [fileName, output] of Object.entries(bundle)) {
         if (output.type !== "chunk") {
           continue;
@@ -26,17 +26,17 @@ export function shebangPlugin(): Plugin {
 export function removeShebangPlugin(): Plugin {
   return {
     name: "unbuild-remove-shebang",
-    renderChunk(code) {
+    renderChunk(code): string {
       return code.replace(SHEBANG_RE, "");
     },
   };
 }
 
-export async function makeExecutable(filePath: string) {
+export async function makeExecutable(filePath: string): Promise<void> {
   await fsp.chmod(filePath, 0o755 /* rwx r-x r-x */).catch(() => {});
 }
 
-export function getShebang(code: string, append = "\n") {
+export function getShebang(code: string, append = "\n"): string {
   const m = code.match(SHEBANG_RE);
   return m ? m + append : "";
 }

src/builders/rollup/stub.ts

@@ -7,7 +7,7 @@ import type { BuildContext } from "../../types";
 import { makeExecutable, getShebang } from "./plugins/shebang";
 import { DEFAULT_EXTENSIONS, resolveAliases } from "./utils";
 
-export async function rollupStub(ctx: BuildContext) {
+export async function rollupStub(ctx: BuildContext): Promise<void> {
   const babelPlugins = ctx.options.stubOptions.jiti.transformOptions?.babel
     ?.plugins as any;
   const importedBabelPlugins: Array<string> = [];

src/builders/rollup/utils.ts

@@ -13,7 +13,7 @@ export const DEFAULT_EXTENSIONS = [
   ".json",
 ];
 
-export function resolveAliases(ctx: BuildContext) {
+export function resolveAliases(ctx: BuildContext): Record<string, string> {
   const aliases: Record<string, string> = {
     [ctx.pkg.name!]: ctx.options.rootDir,
     ...ctx.options.alias,
@@ -57,7 +57,7 @@ export function getChunkFilename(
   ctx: BuildContext,
   chunk: PreRenderedChunk,
   ext: string,
-) {
+): string {
   if (chunk.isDynamicEntry) {
     return `chunks/[name].${ext}`;
   }

src/builders/rollup/watch.ts

@@ -4,7 +4,7 @@ import type { RollupOptions } from "../../types";
 import consola from "consola";
 import chalk from "chalk";
 
-export function rollupWatch(rollupOptions: RollupOptions) {
+export function rollupWatch(rollupOptions: RollupOptions): void {
   const watcher = _rollupWatch(rollupOptions);
 
   let inputs: string[];

src/builders/untyped/index.ts

@@ -16,7 +16,7 @@ import type {
 } from "../../types";
 import consola from "consola";
 
-export async function typesBuild(ctx: BuildContext) {
+export async function typesBuild(ctx: BuildContext): Promise<void> {
   const entries = ctx.options.entries.filter(
     (entry) => entry.builder === "untyped",
   ) as UntypedBuildEntry[];

src/utils.ts

@@ -7,11 +7,11 @@ import type { PackageJson } from "pkg-types";
 import { autoPreset } from "./auto";
 import type { BuildPreset, BuildConfig, BuildContext } from "./types";
 
-export async function ensuredir(path: string) {
+export async function ensuredir(path: string): Promise<void> {
   await fsp.mkdir(dirname(path), { recursive: true });
 }
 
-export function warn(ctx: BuildContext, message: string) {
+export function warn(ctx: BuildContext, message: string): void {
   if (ctx.warnings.has(message)) {
     return;
   }
@@ -19,7 +19,11 @@ export function warn(ctx: BuildContext, message: string) {
   ctx.warnings.add(message);
 }
 
-export async function symlink(from: string, to: string, force = true) {
+export async function symlink(
+  from: string,
+  to: string,
+  force = true,
+): Promise<void> {
   await ensuredir(to);
   if (force) {
     await fsp.unlink(to).catch(() => {});
@@ -27,7 +31,7 @@ export async function symlink(from: string, to: string, force = true) {
   await fsp.symlink(from, to, "junction");
 }
 
-export function dumpObject(obj: Record<string, any>) {
+export function dumpObject(obj: Record<string, any>): string {
   return (
     "{ " +
     Object.keys(obj)
@@ -37,19 +41,19 @@ export function dumpObject(obj: Record<string, any>) {
   );
 }
 
-export function getpkg(id = "") {
+export function getpkg(id = ""): string {
   const s = id.split("/");
   return s[0][0] === "@" ? `${s[0]}/${s[1]}` : s[0];
 }
 
-export async function rmdir(dir: string) {
+export async function rmdir(dir: string): Promise<void> {
   await fsp.unlink(dir).catch(() => {});
   await fsp.rm(dir, { recursive: true, force: true }).catch(() => {});
 }
 
-export function listRecursively(path: string) {
+export function listRecursively(path: string): string[] {
   const filenames = new Set<string>();
-  const walk = (path: string) => {
+  const walk = (path: string): void => {
     const files = readdirSync(path);
     for (const file of files) {
       const fullPath = resolve(path, file);
@@ -143,7 +147,10 @@ export function extractExportFilenames(
   );
 }
 
-export function arrayIncludes(arr: (string | RegExp)[], searchElement: string) {
+export function arrayIncludes(
+  arr: (string | RegExp)[],
+  searchElement: string,
+): boolean {
   return arr.some((entry) =>
     entry instanceof RegExp
       ? entry.test(searchElement)
@@ -151,6 +158,6 @@ export function arrayIncludes(arr: (string | RegExp)[], searchElement: string) {
   );
 }
 
-export function removeExtension(filename: string) {
+export function removeExtension(filename: string): string {
   return filename.replace(/\.(js|mjs|cjs|ts|mts|cts|json|jsx|tsx)$/, "");
 }

src/validate.ts

@@ -5,7 +5,7 @@ import { PackageJson } from "pkg-types";
 import { arrayIncludes, extractExportFilenames, getpkg, warn } from "./utils";
 import { BuildContext } from "./types";
 
-export function validateDependencies(ctx: BuildContext) {
+export function validateDependencies(ctx: BuildContext): void {
   const usedDependencies = new Set<string>();
   const unusedDependencies = new Set<string>(
     Object.keys(ctx.pkg.dependencies || {}),
@@ -50,7 +50,7 @@ export function validatePackage(
   pkg: PackageJson,
   rootDir: string,
   ctx: BuildContext,
-) {
+): void {
   if (!pkg) {
     return;
   }

test/validate.test.ts

@@ -18,6 +18,7 @@ describe("validatePackage", () => {
           "./cli": "./dist/cli",
         },
         module: "dist/mod",
+        // @ts-expect-error TODO: fix pkg-types
         exports: {
           "./runtime/*": "./runtime/*.mjs",
           ".": { node: "./src/index.mts" },
@@ -60,6 +61,7 @@ describe("validateDependencies", () => {
         stub: false,
         alias: {},
         replace: {},
+        // @ts-expect-error
         rollup: {
           replace: false,
           alias: false,
@@ -79,7 +81,11 @@ describe("validateDependencies", () => {
   it("does not print implicit deps warning for peerDependencies", () => {
     const logs: string[] = [];
     consola.mockTypes((type) =>
-      type === "warn" ? (str: string) => logs.push(str) : () => {},
+      type === "warn"
+        ? (str: string): void => {
+            logs.push(str);
+          }
+        : (): void => {},
     );
 
     validateDependencies({
@@ -99,6 +105,7 @@ describe("validateDependencies", () => {
         stub: false,
         alias: {},
         replace: {},
+        // @ts-expect-error
         rollup: {
           replace: false,
           alias: false,