Fix lint for string exports

src/lint.ts

@@ -83,13 +83,13 @@ export function lint(pkg: PackageMetadata) {
       }
     }
   } else {
+    // Validate CJS package
     if (main && path.extname(main) === '.mjs') {
       state.badMainExtension = true
     }
-    // Validate CJS package
     if (exports) {
       if (typeof exports === 'string') {
-        if (!hasCjsExtension(exports)) {
+        if (path.extname(exports) === '.mjs') {
           state.badMainExport = true
         }
       }
@@ -127,9 +127,15 @@ export function lint(pkg: PackageMetadata) {
     )
   }
   if (state.badMainExport) {
-    logger.warn(
-      'Cannot export `exports` field with .cjs extension in ESM package, only .mjs and .js extensions are allowed',
-    )
+    if (isESM) {
+      logger.warn(
+        'Cannot export `exports` field with .cjs extension in ESM package, only .mjs and .js extensions are allowed',
+      )
+    } else {
+      logger.warn(
+        'Cannot export `exports` field with .mjs extension in CJS package, only .js and .cjs extensions are allowed',
+      )
+    }
   }
 
   if (state.invalidExportsFieldType) {

test/integration.test.ts

@@ -45,7 +45,6 @@ const testCases: {
   },
   {
     name: 'externals',
-    args: ['index.js', '-o', './dist/index.js'],
     async expected(dir) {
       const distFile = join(dir, './dist/index.js')
       const content = await fsp.readFile(distFile, { encoding: 'utf-8' })
@@ -55,7 +54,6 @@ const testCases: {
   },
   {
     name: 'duplicate-entry',
-    args: [],
     async expected(dir, { stdout }) {
       const distFiles = [
         'dist/index.js',
@@ -72,7 +70,6 @@ const testCases: {
   },
   {
     name: 'ts-error',
-    args: ['index.ts', '-o', './dist/index.js'],
     async expected(dir, { stdout, stderr }) {
       const distFile = join(dir, './dist/index.js')
       expect(stderr).toMatch(/Could not load TypeScript compiler/)
@@ -89,16 +86,14 @@ const testCases: {
     },
   },
   {
-    name: 'no-ts-require-for-js',
-    args: ['index.js', '-o', './dist/index.js'],
+    name: 'js-only',
     async expected(dir) {
       const distFile = join(dir, './dist/index.js')
       expect(await existsFile(distFile)).toBe(true)
     },
   },
   {
     name: 'entry-index-index',
-    args: [],
     async expected(dir) {
       await assertFilesContent(dir, {
         './dist/index.js': /'index'/,
@@ -108,7 +103,6 @@ const testCases: {
   },
   {
     name: 'pkg-exports',
-    args: ['index.js'],
     async expected(dir) {
       const distFiles = [
         'dist/index.cjs',
@@ -240,8 +234,7 @@ const testCases: {
   },
   {
     name: 'single-entry',
-    args: [],
-    async expected(dir, { stdout }) {
+    async expected(dir, { stdout, stderr }) {
       const distFiles = [
         join(dir, './dist/index.js'),
         join(dir, './dist/index.d.ts'),
@@ -260,6 +253,8 @@ const testCases: {
       dist/index.d.ts
       dist/index.js`
 
+      expect(stderr).not.toContain('Cannot export `exports` field with')
+
       const rawStdout = stripANSIColor(stdout)
       log.split('\n').forEach((line: string) => {
         expect(rawStdout).toContain(line.trim())

test/integration/js-only/package.json

@@ -0,0 +1,3 @@
+{
+  "exports": "./dist/index.js"
+}