Add enhancer function check

Author: compulim

packages/api/src/middleware/private/templateMiddleware.check.test.tsx

@@ -0,0 +1,13 @@
+import templateMiddleware from './templateMiddleware';
+
+test('should warn if middleware did not return function', () => {
+  const warn = jest.fn();
+  const template = templateMiddleware('Check');
+
+  jest.spyOn(console, 'warn').mockImplementation(warn);
+
+  template.extractMiddleware([() => 1 as any]);
+
+  expect(warn).toHaveBeenCalledTimes(1);
+  expect(warn).toHaveBeenNthCalledWith(1, expect.stringContaining('must return enhancer function'));
+});

packages/api/src/middleware/private/templateMiddleware.ts

@@ -25,11 +25,19 @@ function templateMiddleware<Request = any, Props extends {} = EmptyObject>(name:
   ): readonly Middleware[] => {
     if (middleware) {
       if (isArrayOfFunction(middleware)) {
-        // TODO: [P*] We assume middleware is Function[], we should do more checks.
         return Object.freeze(
           middleware
-            // TODO: [P*] Checks if the return value is of type function or false.
-            .map(middleware => middleware(name) as ReturnType<Middleware> | false)
+            .map(middleware => {
+              const result = middleware(name);
+
+              if (typeof result !== 'function') {
+                console.warn(`botframework-webchat: ${name}.middleware must return enhancer function`);
+
+                return false;
+              }
+
+              return result;
+            })
             .filter((enhancer): enhancer is ReturnType<Middleware> => !!enhancer)
             .map(enhancer => () => enhancer)
         );