fix: add error message if unable to find cron expression for schedule…

…d function (#1123)

* fix: add error message if cron expression not found or invalid in isc of scheduled funcs

src/runtimes/node/in_source_config/index.ts

@@ -23,6 +23,10 @@ export const findISCDeclarationsInPath = async (sourcePath: string): Promise<ISC
   }
 
   const imports = ast.body.flatMap((node) => getImports(node, IN_SOURCE_CONFIG_MODULE))
+
+  const scheduledFuncsExpected = imports.filter(({ imported }) => imported === 'schedule').length
+  let scheduledFuncsFound = 0
+
   const getAllBindings = createBindingsMethod(ast.body)
   const mainExports = getMainExport(ast.body, getAllBindings)
   const iscExports = mainExports
@@ -34,16 +38,29 @@ export const findISCDeclarationsInPath = async (sourcePath: string): Promise<ISC
       }
 
       switch (matchingImport.imported) {
-        case 'schedule':
-          return parseSchedule({ args }, getAllBindings)
+        case 'schedule': {
+          const parsed = parseSchedule({ args }, getAllBindings)
+
+          if (parsed.schedule) {
+            scheduledFuncsFound += 1
+          }
 
+          return parsed
+        }
         default:
         // no-op
       }
 
       return null
     })
     .filter(nonNullable)
+
+  if (scheduledFuncsFound < scheduledFuncsExpected) {
+    throw new Error(
+      'Warning: unable to find cron expression for scheduled function. `schedule` imported but not called or exported. If you meant to schedule a function, please check that `schedule` is invoked with an appropriate cron expression.',
+    )
+  }
+
   const mergedExports: ISCValues = iscExports.reduce((acc, obj) => ({ ...acc, ...obj }), {})
 
   return mergedExports

tests/fixtures/in-source-config/functions/cron_esm_additional_schedule_import.js

@@ -0,0 +1,9 @@
+import { schedule as nfySchedule } from '@netlify/functions'
+import { schedule } from '../node_modules/@netlify/functions/index.js'
+// make sure cron expression is found/doesn't error if `schedule` is also imported from another source
+
+schedule()
+
+export const handler = nfySchedule('@daily', () => {
+  // function handler
+})

tests/fixtures/in-source-config/functions_missing_cron_expression/cron_cjs_invalid_cron_expression.js

@@ -0,0 +1,5 @@
+const { schedule } = require('@netlify/functions')
+
+module.exports.handler = schedule(null, () => {
+  // function handler
+})

tests/fixtures/in-source-config/functions_missing_cron_expression/cron_cjs_schedule_not_called.js

@@ -0,0 +1,4 @@
+const { schedule } = require('@netlify/functions')
+
+// Should throw an error that `schedule` is imported but cron expression not found
+module.exports.handler = {}

tests/fixtures/in-source-config/functions_missing_cron_expression/cron_esm_schedule_not_called.js

@@ -0,0 +1,5 @@
+// eslint-disable-next-line n/no-unsupported-features/es-syntax
+import { schedule } from '@netlify/functions'
+
+// Should throw an error that schedule is imported but cron expression not found
+export const handler = {}

tests/main.js

@@ -2633,7 +2633,7 @@ testMany(
   'Finds in-source config declarations using the `schedule` helper',
   ['bundler_default', 'bundler_esbuild', 'bundler_nft'],
   async (options, t) => {
-    const FUNCTIONS_COUNT = 11
+    const FUNCTIONS_COUNT = 12
     const { files } = await zipFixture(t, join('in-source-config', 'functions'), {
       opts: options,
       length: FUNCTIONS_COUNT,
@@ -2647,6 +2647,22 @@ testMany(
   },
 )
 
+testMany(
+  'Throws error when `schedule` helper is imported but cron expression not found',
+  ['bundler_default', 'bundler_esbuild', 'bundler_nft'],
+  async (options, t) => {
+    const rejected = (error) => {
+      t.true(error.message.startsWith('Warning: unable to find cron expression for scheduled function.'))
+    }
+
+    const FUNCTIONS_COUNT = 3
+    await zipFixture(t, join('in-source-config', 'functions_missing_cron_expression'), {
+      opts: options,
+      length: FUNCTIONS_COUNT,
+    }).catch(rejected)
+  },
+)
+
 test('listFunctions surfaces schedule config property', async (t) => {
   const functions = await listFunctions(join(FIXTURES_DIR, 'many-functions'), {
     config: {
@@ -2663,7 +2679,7 @@ test('listFunctions includes in-source config declarations', async (t) => {
   const functions = await listFunctions(join(FIXTURES_DIR, 'in-source-config', 'functions'), {
     parseISC: true,
   })
-  const FUNCTIONS_COUNT = 11
+  const FUNCTIONS_COUNT = 12
   t.is(functions.length, FUNCTIONS_COUNT)
   functions.forEach((func) => {
     t.is(func.schedule, '@daily')