feat(resolveExtensions): added support for custom resolve extensions …

…esbuild setting

src/constants.ts

@@ -2,3 +2,4 @@ export const SERVERLESS_FOLDER = '.serverless';
 export const BUILD_FOLDER = '.build';
 export const WORK_FOLDER = '.esbuild';
 export const ONLY_PREFIX = '__only_';
+export const DEFAULT_EXTENSIONS = ['.ts', '.js', '.jsx', '.tsx'];

src/helper.ts

@@ -11,6 +11,7 @@ import type Serverless from 'serverless';
 import type ServerlessPlugin from 'serverless/classes/Plugin';
 import type { Configuration, DependencyMap, FunctionEntry } from './types';
 import type { EsbuildFunctionDefinitionHandler } from './types';
+import { DEFAULT_EXTENSIONS } from './constants';
 
 export function asArray<T>(data: T | T[]): T[] {
   return Array.isArray(data) ? data : [data];
@@ -27,7 +28,8 @@ export function assertIsString(input: unknown, message = 'input is not a string'
 export function extractFunctionEntries(
   cwd: string,
   provider: string,
-  functions: Record<string, Serverless.FunctionDefinitionHandler>
+  functions: Record<string, Serverless.FunctionDefinitionHandler>,
+  resolveExtensions?: string[]
 ): FunctionEntry[] {
   // The Google provider will use the entrypoint not from the definition of the
   // handler function, but instead from the package.json:main field, or via a
@@ -69,7 +71,7 @@ export function extractFunctionEntries(
       // replace only last instance to allow the same name for file and handler
       const fileName = handler.substring(0, fnNameLastAppearanceIndex);
 
-      const extensions = ['.ts', '.js', '.jsx', '.tsx'];
+      const extensions = resolveExtensions ?? DEFAULT_EXTENSIONS;
 
       for (const extension of extensions) {
         // Check if the .{extension} files exists. If so return that to watch

src/index.ts

@@ -345,7 +345,12 @@ class EsbuildServerlessPlugin implements ServerlessPlugin {
   }
 
   get functionEntries() {
-    return extractFunctionEntries(this.serviceDirPath, this.serverless.service.provider.name, this.functions);
+    return extractFunctionEntries(
+      this.serviceDirPath,
+      this.serverless.service.provider.name,
+      this.functions,
+      this.buildOptions?.resolveExtensions
+    );
   }
 
   watch(): void {

src/tests/helper.test.ts

@@ -135,6 +135,35 @@ describe('extractFunctionEntries', () => {
       ]);
     });
 
+    it('should allow resolve extensions custom Esbuild setting', () => {
+      jest.mocked(fs.existsSync).mockReturnValue(true);
+      const functionDefinitions = {
+        function1: {
+          events: [],
+          handler: './file1.handler',
+        },
+        function2: {
+          events: [],
+          handler: './file2.handler',
+        },
+      };
+
+      const fileNames = extractFunctionEntries(cwd, 'aws', functionDefinitions, ['.custom.ts']);
+
+      expect(fileNames).toStrictEqual([
+        {
+          entry: 'file1.custom.ts',
+          func: functionDefinitions.function1,
+          functionAlias: 'function1',
+        },
+        {
+          entry: 'file2.custom.ts',
+          func: functionDefinitions.function2,
+          functionAlias: 'function2',
+        },
+      ]);
+    });
+
     it('should not return entries for handlers which have skipEsbuild set to true', async () => {
       jest.mocked(fs.existsSync).mockReturnValue(true);
       const functionDefinitions = {