feat(testing): set transpileOnly=true ...

... and use the ForkTsCheckerWebpackPlugin
for the cypress test execution.

Closes nrwl#1871

packages/cypress/package.json

@@ -38,6 +38,7 @@
     "@angular-devkit/architect": "0.803.3",
     "@angular-devkit/core": "8.3.3",
     "@cypress/webpack-preprocessor": "~4.1.0",
+    "fork-ts-checker-webpack-plugin": "^0.4.9",
     "tree-kill": "1.2.1",
     "ts-loader": "5.3.1",
     "tsconfig-paths-webpack-plugin": "3.2.0",

packages/cypress/src/plugins/preprocessor.ts

@@ -2,6 +2,8 @@ import * as wp from '@cypress/webpack-preprocessor';
 import { TsconfigPathsPlugin } from 'tsconfig-paths-webpack-plugin';
 import * as nodeExternals from 'webpack-node-externals';
 
+import ForkTsCheckerWebpackPlugin = require('fork-ts-checker-webpack-plugin');
+
 export function preprocessTypescript(config: any) {
   if (!config.env.tsConfig) {
     throw new Error(
@@ -35,11 +37,18 @@ export function getWebpackConfig(config: any) {
           options: {
             configFile: config.env.tsConfig,
             // https://github.com/TypeStrong/ts-loader/pull/685
-            experimentalWatchApi: true
+            experimentalWatchApi: true,
+            // https://github.com/cypress-io/cypress/issues/2316
+            transpileOnly: true
           }
         }
       ]
     },
+    plugins: [
+      new ForkTsCheckerWebpackPlugin({
+        tsconfig: config.env.tsConfig
+      })
+    ],
     externals: [nodeExternals()]
   };
 }