feat: detect literal export as default as a v2 API

src/runtimes/node/in_source_config/index.ts

@@ -198,4 +198,5 @@ export type ISCExportWithObject = {
   object: Record<string, unknown>
 }
 export type ISCExportOther = { type: 'other' }
-export type ISCExport = ISCExportWithCallExpression | ISCExportWithObject | ISCExportOther
+export type ISCDefaultExport = { type: 'default' }
+export type ISCExport = ISCExportWithCallExpression | ISCExportWithObject | ISCExportOther | ISCDefaultExport

src/runtimes/node/in_source_config/properties/schedule.ts

@@ -1,3 +1,5 @@
+import { isExpression } from '@babel/types'
+
 import type { BindingMethod } from '../../parser/bindings.js'
 import type { ISCHandlerArg } from '../index.js'
 
@@ -7,7 +9,7 @@ export const parse = ({ args }: { args: ISCHandlerArg[] }, getAllBindings: Bindi
   if (expression.type === 'Identifier') {
     const binding = getAllBindings().get(expression.name)
 
-    if (binding) {
+    if (binding && isExpression(binding)) {
       expression = binding
     }
   }

src/runtimes/node/parser/bindings.ts

@@ -1,6 +1,6 @@
-import type { Expression, Statement, VariableDeclaration } from '@babel/types'
+import type { Declaration, Expression, Statement, VariableDeclaration } from '@babel/types'
 
-type Bindings = Map<string, Expression>
+type Bindings = Map<string, Expression | Declaration>
 
 const getBindingFromVariableDeclaration = function (node: VariableDeclaration, bindings: Bindings): void {
   node.declarations.forEach((declaration) => {
@@ -11,7 +11,9 @@ const getBindingFromVariableDeclaration = function (node: VariableDeclaration, b
 }
 
 const getBindingsFromNode = function (node: Statement, bindings: Bindings): void {
-  if (node.type === 'VariableDeclaration') {
+  if (node.type === 'FunctionDeclaration' && node.id?.name) {
+    bindings.set(node.id.name, node)
+  } else if (node.type === 'VariableDeclaration') {
     // A variable was created, so create it and store the potential value
     getBindingFromVariableDeclaration(node, bindings)
   } else if (

src/runtimes/node/parser/exports.ts

@@ -1,4 +1,5 @@
 import type {
+  Declaration,
   ExportDefaultDeclaration,
   ExportNamedDeclaration,
   ExportSpecifier,
@@ -40,6 +41,11 @@ export const traverseNodes = (nodes: Statement[], getAllBindings: BindingMethod)
     const esmHandlerExports = getNamedESMExport(node, 'handler', getAllBindings)
 
     if (esmHandlerExports.length !== 0) {
+      if (esmHandlerExports.some(({ type }) => type === 'default')) {
+        hasDefaultExport = true
+
+        return
+      }
       handlerExports.push(...esmHandlerExports)
 
       return
@@ -132,6 +138,16 @@ const getNamedESMExport = (node: Statement, name: string, getAllBindings: Bindin
   return exports
 }
 
+/**
+ * Check if the node is an `ExportSpecifier` that has a identifier with a default export:
+ * - `export { x as default }`
+ */
+const isDefaultExport = (node: ExportNamedDeclaration['specifiers'][number]): node is ExportSpecifier => {
+  const { type, exported } = node
+
+  return type === 'ExportSpecifier' && exported.type === 'Identifier' && exported.name === 'default'
+}
+
 /**
  * Check if the node is an `ExportSpecifier` that has a named export with
  * the given name, either as:
@@ -234,20 +250,31 @@ const getExportsFromBindings = (
   specifiers: ExportNamedDeclaration['specifiers'],
   name: string,
   getAllBindings: BindingMethod,
-) => {
+): ISCExport[] => {
+  const defaultExport = specifiers.find((node) => isDefaultExport(node))
+
+  if (defaultExport && defaultExport.type === 'ExportSpecifier') {
+    const binding = getAllBindings().get(defaultExport.local.name)
+
+    if (binding?.type === 'ArrowFunctionExpression' || binding?.type === 'FunctionDeclaration') {
+      return [{ type: 'default' }]
+    }
+  }
+
   const specifier = specifiers.find((node) => isNamedExport(node, name))
 
   if (!specifier || specifier.type !== 'ExportSpecifier') {
     return []
   }
 
   const binding = getAllBindings().get(specifier.local.name)
+
   const exports = getExportsFromExpression(binding)
 
   return exports
 }
 
-const getExportsFromExpression = (node: Expression | undefined | null): ISCExport[] => {
+const getExportsFromExpression = (node: Expression | Declaration | undefined | null): ISCExport[] => {
   switch (node?.type) {
     case 'CallExpression': {
       const { arguments: args, callee } = node

tests/unit/runtimes/node/in_source_config.test.ts

@@ -82,7 +82,7 @@ describe('`schedule` helper', () => {
     const source = `import { schedule } from "@netlify/functions"
 
     const handler = schedule("@daily", () => {})
-    
+
     export { handler }`
 
     const isc = parseSource(source, options)
@@ -140,7 +140,7 @@ describe('V2 API', () => {
       const source = `export default async () => {
         return new Response("Hello!")
       }
-  
+
       export const handler = function () { return { statusCode: 200, body: "Hello!" } }`
 
       const isc = parseSource(source, options)
@@ -150,14 +150,61 @@ describe('V2 API', () => {
 
     test('ESM file with no default export and a `handler` export', () => {
       const source = `const handler = async () => ({ statusCode: 200, body: "Hello" })
-      
+
       export { handler }`
 
       const isc = parseSource(source, options)
 
       expect(isc).toEqual({ inputModuleFormat: 'esm', runtimeAPIVersion: 1 })
     })
 
+    test('ESM file with default exporting a function', () => {
+      const source = `
+      const handler = async () => ({ statusCode: 200, body: "Hello" })
+      export default handler;`
+
+      const isc = parseSource(source, options)
+      expect(isc).toEqual({ inputModuleFormat: 'esm', routes: [], runtimeAPIVersion: 2 })
+    })
+
+    test('ESM file with default export of variable and separate handler export', () => {
+      const source = `
+      const foo = 'foo'
+      export default foo;
+      export const handler = () => ({ statusCode: 200, body: "Hello" })`
+
+      const isc = parseSource(source, options)
+      expect(isc).toEqual({ inputModuleFormat: 'esm', runtimeAPIVersion: 1 })
+    })
+
+    test('ESM file with default export wrapped in a literal from an arrow function', () => {
+      const source = `
+      const handler = async () => ({ statusCode: 200, body: "Hello" })
+      export const config = { schedule: "@daily" }
+      export { handler as default };`
+
+      const isc = parseSource(source, options)
+      expect(isc).toEqual({ inputModuleFormat: 'esm', routes: [], schedule: '@daily', runtimeAPIVersion: 2 })
+    })
+
+    test('ESM file with default export wrapped in a literal from a function', () => {
+      const source = `
+      async function handler(){ return { statusCode: 200, body: "Hello" }}
+      export { handler as default };`
+
+      const isc = parseSource(source, options)
+      expect(isc).toEqual({ inputModuleFormat: 'esm', routes: [], runtimeAPIVersion: 2 })
+    })
+
+    test('ESM file with default export exporting a constant', () => {
+      const source = `
+      const foo = "bar"
+      export { foo as default };`
+
+      const isc = parseSource(source, options)
+      expect(isc).toEqual({ inputModuleFormat: 'esm', runtimeAPIVersion: 1 })
+    })
+
     test('TypeScript file with a default export and no `handler` export', () => {
       const source = `export default async (req: Request) => {
         return new Response("Hello!")
@@ -172,7 +219,7 @@ describe('V2 API', () => {
       const source = `exports.default = async () => {
         return new Response("Hello!")
       }
-  
+
       exports.handler = async () => ({ statusCode: 200, body: "Hello!" })`
 
       const isc = parseSource(source, options)
@@ -196,7 +243,7 @@ describe('V2 API', () => {
       const source = `export default async () => {
         return new Response("Hello!")
       }
-  
+
       export const config = {
         schedule: "@daily"
       }`
@@ -212,7 +259,7 @@ describe('V2 API', () => {
       const source = `export default async () => {
         return new Response("Hello!")
       }
-  
+
       export const config = {
         method: ["GET", "POST"]
       }`
@@ -226,7 +273,7 @@ describe('V2 API', () => {
       const source = `export default async () => {
         return new Response("Hello!")
       }
-  
+
       export const config = {
         method: "GET"
       }`
@@ -246,7 +293,7 @@ describe('V2 API', () => {
           const source = `export default async () => {
             return new Response("Hello!")
           }
-      
+
           export const config = {
             path: "missing-slash"
           }`
@@ -269,7 +316,7 @@ describe('V2 API', () => {
           const source = `export default async () => {
             return new Response("Hello!")
           }
-      
+
           export const config = {
             path: "/products("
           }`
@@ -292,7 +339,7 @@ describe('V2 API', () => {
           const source = `export default async () => {
             return new Response("Hello!")
           }
-      
+
           export const config = {
             path: {
               url: "/products"
@@ -317,7 +364,7 @@ describe('V2 API', () => {
           const source = `export default async () => {
             return new Response("Hello!")
           }
-      
+
           export const config = {
             path: ["/store", "/products("]
           }`
@@ -340,7 +387,7 @@ describe('V2 API', () => {
           const source = `export default async () => {
             return new Response("Hello!")
           }
-      
+
           export const config = {
             path: ["/store", 42]
           }`
@@ -363,7 +410,7 @@ describe('V2 API', () => {
           const source = `export default async () => {
             return new Response("Hello!")
           }
-      
+
           export const config = {
             path: ["/store", null]
           }`
@@ -386,7 +433,7 @@ describe('V2 API', () => {
           const source = `export default async () => {
             return new Response("Hello!")
           }
-      
+
           export const config = {
             path: ["/store", undefined]
           }`
@@ -408,7 +455,7 @@ describe('V2 API', () => {
         const source = `export default async () => {
           return new Response("Hello!")
         }
-    
+
         export const config = {
           path: "/products"
         }`
@@ -422,7 +469,7 @@ describe('V2 API', () => {
         const source = `exports.default = async () => {
           return new Response("Hello!")
         }
-    
+
         exports.config = {
           path: "/products"
         }`
@@ -437,7 +484,7 @@ describe('V2 API', () => {
       const source = `export default async () => {
         return new Response("Hello!")
       }
-  
+
       export const config = {
         path: "/store/:category/products/:product-id"
       }`
@@ -457,7 +504,7 @@ describe('V2 API', () => {
       const source = `export default async () => {
         return new Response("Hello!")
       }
-  
+
       export const config = {
         path: [
           "/store/:category/products/:product-id",
@@ -487,7 +534,7 @@ describe('V2 API', () => {
       const source = `export default async () => {
         return new Response("Hello!")
       }
-  
+
       export const config = {
         path: ["/products", "/products"]
       }`