fix: remove unnecessary export alias. (#35)

Author: knightedcodemonkey

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "@knighted/module",
-  "version": "1.2.0",
+  "version": "1.2.1",
   "description": "Bidirectional transform for ES modules and CommonJS.",
   "type": "module",
   "main": "dist/module.js",

package.json

@@ -805,7 +805,10 @@ const format = async (src: string, ast: ParseResult, opts: FormatterOptions) =>
           seen.add(propName)
           if (rhs.type === 'Identifier') {
             const rhsId = rhsSourceFor(rhs)
-            if (rhsId === rhs.name) {
+            const rhsName = rhs.name
+            if (rhsId === rhsName && rhsName === propName) {
+              exportsOut.push(`export { ${propName} };`)
+            } else if (rhsId === rhsName) {
               exportsOut.push(`export { ${rhsId} as ${propName} };`)
             } else {
               exportsOut.push(`export const ${propName} = ${rhsId};`)
@@ -815,7 +818,12 @@ const format = async (src: string, ast: ParseResult, opts: FormatterOptions) =>
           }
         }
 
-        replacements.push({ start: write.start, end: write.end })
+        // Trim trailing whitespace and one optional semicolon so the idiomatic export
+        // replacement does not leave the original `;` behind (avoids emitting `;;`).
+        let end = write.end
+        while (end < src.length && (src[end] === ' ' || src[end] === '\t')) end++
+        if (end < src.length && src[end] === ';') end++
+        replacements.push({ start: write.start, end })
       }
 
       if (!seen.size) return { ok: false, reason: 'no-seen' }

src/format.ts

@@ -0,0 +1,5 @@
+function example() {
+  return 'ok'
+}
+
+exports.example = example

test/fixtures/idiomaticShorthand.cjs

@@ -1179,6 +1179,26 @@ describe('@knighted/module', () => {
     assert.equal((mod as any).bar(), 'bar')
   })
 
+  it('emits shorthand exports when names match', async t => {
+    const fixturePath = join(fixtures, 'idiomaticShorthand.cjs')
+    const outFile = join(fixtures, 'idiomaticShorthand.mjs')
+
+    t.after(() => rm(outFile, { force: true }))
+
+    const result = await transform(fixturePath, { target: 'module' })
+    await writeFile(outFile, result)
+
+    assert.equal(result.includes('__exports'), false)
+    assert.ok(result.includes('export { example };'))
+    assert.equal(result.includes(';;'), false)
+
+    const { status } = spawnSync('node', [outFile], { stdio: 'inherit' })
+    assert.equal(status, 0)
+
+    const mod = await import(pathToFileURL(outFile).href)
+    assert.equal((mod as any).example(), 'ok')
+  })
+
   it('respects idiomaticExports: off and keeps helper bag', async t => {
     const fixturePath = join(fixtures, 'idiomaticSafe.cjs')
     const outFile = join(fixtures, 'idiomaticOff.mjs')