validate app on registration (#3)

package.json

@@ -1,12 +1,12 @@
 {
   "name": "@efstajas/tela",
-  "version": "0.3.0",
+  "version": "0.3.2",
   "description": "A framework for building Intercom Canvas Kit applications.",
   "main": "lib/index.js",
   "scripts": {
     "build": "tsc"
   },
-  "keywords": ["intercom", "canvas kit", "custom apps", "express"],
+  "keywords": ["intercom", "canvas kit", "custom apps", "express", "typescript"],
   "repository": {
     "type" : "git",
     "url" : "https://github.com/efstajas/tela.git"

src/methods/appValidator/errorTemplates/handlerNotFunction.ts

@@ -0,0 +1,2 @@
+export default (appName: string, methodName: string) =>
+  `Expected handler ${methodName} of app ${appName} to be function that returns Promise<Component[]> or Component[]`

src/methods/appValidator/errorTemplates/hookNotFunction.ts

@@ -0,0 +1,2 @@
+export default (appName: string, hookName: string) =>
+  `Expected hook ${hookName} of app ${appName} to be function like (req, res, next, context) => void`

src/methods/appValidator/errorTemplates/hooksNotObject.ts

@@ -0,0 +1,2 @@
+export default (appName: string) =>
+  `Expected 'hooks' member of app ${appName} to be object of shape { [key: string]: (req, res, next, context) => void }`

src/methods/appValidator/errorTemplates/missingMethod.ts

@@ -0,0 +1,2 @@
+export default (appName: string, methodName: string) =>
+  `App ${appName} is missing required method ${methodName}`

src/methods/appValidator/validateApp.ts

@@ -0,0 +1,50 @@
+import { App } from '../../app.types'
+import missingMethodTemplate from './errorTemplates/missingMethod'
+import hooksNotObjectTemplate from './errorTemplates/hooksNotObject'
+import handlerNotFunctionTemplate from './errorTemplates/handlerNotFunction'
+import hookNotFunctionTemplate from './errorTemplates/hookNotFunction'
+
+export default (appName: string, app: App) => {
+  const requiredMembers = ['initialize']
+  const optionalMembers = ['submit', 'configure', 'hooks']
+  const possibleMembers = requiredMembers.concat(optionalMembers)
+
+  const appMethods = Object.keys(app)
+
+  // check if all required methods are present
+
+  requiredMembers.forEach((key: string) => {
+    if (!appMethods.includes(key)) {
+      throw new Error(missingMethodTemplate(appName, key))
+    }
+  })
+
+  // Check if members are of expected type
+
+  const appAsAny = (app as any)
+
+  possibleMembers.forEach((key: string) => {
+    const memberType = typeof appAsAny[key]
+
+    if (appAsAny[key]) {
+      switch (key) {
+        case 'hooks':
+          if (memberType !== 'object') {
+            throw new Error(hooksNotObjectTemplate(appName))
+          }
+
+          Object.keys(appAsAny.hooks).forEach((h: string) => {
+            if (typeof appAsAny.hooks[h] !== 'function') {
+              throw new Error(hookNotFunctionTemplate(appName, h))
+            }
+          })
+          break
+        default:
+          if (memberType !== 'function') {
+            throw new Error(handlerNotFunctionTemplate(appName, key))
+          }
+          break
+      }
+    }
+  })
+}

src/tela.class.ts

@@ -4,11 +4,14 @@ import * as bodyParser from 'body-parser'
 import { App } from './app.types'
 import constructHandlerContext from './methods/construct-handler-context'
 import constructRouter from './methods/construct-router'
+import validateApp from './methods/appValidator/validateApp'
 
 export default class Tela {
   private server = express().use(bodyParser.json());
 
   public registerApp = async (appName: string, app: App) => {
+    validateApp(appName, app)
+
     const router = constructRouter(appName, app)
 
     const path = `/${appName.toLowerCase()}`