fix: remove duplicate functions and let .js take precedence (#359)

* feat: remove duplicate functions and let .js take precedence

* fix: use entire extensions list to check function precedence

* fix: filter out function files based on extension before parsing them

* fix: filter out function files based on extension before parsing them

* fix: filter out function files based on extension before parsing them

node/finder.test.ts

@@ -0,0 +1,20 @@
+import { test, expect } from 'vitest'
+
+import { removeDuplicatesByExtension } from './finder.js'
+
+test('filters out any duplicate files based on the extension', () => {
+  const functions = [
+    'file1.js',
+    'file1.ts',
+    'file2.tsx',
+    'file2.jsx',
+    'file3.tsx',
+    'file3.js',
+    'file4.ts',
+    'file5.ts',
+    'file5.tsx',
+  ]
+  const expected = ['file1.js', 'file2.jsx', 'file3.js', 'file4.ts', 'file5.ts']
+
+  expect(removeDuplicatesByExtension(functions)).toStrictEqual(expected)
+})

node/finder.ts

@@ -1,16 +1,36 @@
 import { promises as fs } from 'fs'
-import { basename, extname, join } from 'path'
+import { basename, extname, join, parse } from 'path'
 
 import { EdgeFunction } from './edge_function.js'
 import { nonNullable } from './utils/non_nullable.js'
 
-const ALLOWED_EXTENSIONS = new Set(['.js', '.jsx', '.ts', '.tsx'])
+// the order of the allowed extensions is also the order we remove duplicates
+// with a lower index meaning a higher precedence over the others
+const ALLOWED_EXTENSIONS = ['.js', '.jsx', '.ts', '.tsx']
+
+export const removeDuplicatesByExtension = (functions: string[]) => {
+  const seen = new Map()
+
+  return Object.values(
+    functions.reduce((acc, path) => {
+      const { ext, name } = parse(path)
+      const extIndex = ALLOWED_EXTENSIONS.indexOf(ext)
+
+      if (!seen.has(name) || seen.get(name) > extIndex) {
+        seen.set(name, extIndex)
+        return { ...acc, [name]: path }
+      }
+
+      return acc
+    }, {}),
+  ) as string[]
+}
 
 const findFunctionInDirectory = async (directory: string): Promise<EdgeFunction | undefined> => {
   const name = basename(directory)
-  const candidatePaths = [...ALLOWED_EXTENSIONS]
-    .flatMap((extension) => [`${name}${extension}`, `index${extension}`])
-    .map((filename) => join(directory, filename))
+  const candidatePaths = ALLOWED_EXTENSIONS.flatMap((extension) => [`${name}${extension}`, `index${extension}`]).map(
+    (filename) => join(directory, filename),
+  )
 
   let functionPath
 
@@ -48,7 +68,7 @@ const findFunctionInPath = async (path: string): Promise<EdgeFunction | undefine
 
   const extension = extname(path)
 
-  if (ALLOWED_EXTENSIONS.has(extension)) {
+  if (ALLOWED_EXTENSIONS.includes(extension)) {
     return { name: basename(path, extension), path }
   }
 }
@@ -57,7 +77,7 @@ const findFunctionsInDirectory = async (baseDirectory: string) => {
   let items: string[] = []
 
   try {
-    items = await fs.readdir(baseDirectory)
+    items = await fs.readdir(baseDirectory).then(removeDuplicatesByExtension)
   } catch {
     // no-op
   }