feat(transformers): Disable JS in preview on error

client/epics/err-epic.js

@@ -4,7 +4,7 @@ export default function errorSaga(actions) {
   return actions.filter(({ error }) => !!error)
     .map(({ error }) => error)
     .doOnNext(error => console.error(error))
-    .map(() => makeToast({
+    .map(error => makeToast({
-      message: 'Something went wrong, please try again later'
+      message: error.message || 'Something went wrong, please try again later'
     }));
 }

common/app/routes/Challenges/Preview.jsx

@@ -1,4 +1,5 @@
-import React, { PropTypes, PureComponent } from 'react';
+import React, { PureComponent } from 'react';
+import PropTypes from 'prop-types';
 import { connect } from 'react-redux';
 
 import ns from './ns.json';

common/app/routes/Challenges/rechallenge/builders.js

@@ -50,22 +50,28 @@ const wrapInStyle = partial(transformContents, (content) => (
 const setExtToHTML = partial(setExt, 'html');
 const padContentWithJsCatch = partial(compileHeadTail, jsCatch);
 const padContentWithHTMLCatch = partial(compileHeadTail, htmlCatch);
+function transformErrorProtect(fn) {
+  return cond([
+    [ matchesProperty('transformError', false), fn ],
+    [ stubTrue, identity ]
+  ]);
+}
 
-export const jsToHtml = cond([
+export const jsToHtml = transformErrorProtect(cond([
   [
     matchesProperty('ext', 'js'),
     flow(padContentWithJsCatch, wrapInScript, setExtToHTML)
   ],
   [ stubTrue, identity ]
-]);
+]));
 
-export const cssToHtml = cond([
+export const cssToHtml = transformErrorProtect(cond([
   [
     matchesProperty('ext', 'css'),
     flow(padContentWithHTMLCatch, wrapInStyle, setExtToHTML)
   ],
 	[ stubTrue, identity ]
-]);
+]));
 
 // FileStream::concactHtml(
 //   required: [ ...Object ],

common/app/routes/Challenges/rechallenge/transformers.js

@@ -1,7 +1,9 @@
 import {
+  attempt,
   cond,
   flow,
   identity,
+  isError,
   matchesProperty,
   overEvery,
   overSome,
@@ -105,15 +107,42 @@ export const replaceNBSP = cond([
   [ stubTrue, identity ]
 ]);
 
+const transformErrorWarn = '/* __fcc--TransformError__ */';
+
+function tryJSTransform(wrap = identity, defaultAssignment = 'code') {
+  return function transformWrappedPoly(source) {
+    const result = attempt(wrap, source);
+    if (isError(result)) {
+      const friendlyError = `${result}`
+        .match(/[\w\W]+?\n/)[0]
+        .replace(' unknown:', '');
+      console.error(friendlyError);
+      return `var ${defaultAssignment} = null; ${transformErrorWarn}`;
+    }
+    return result;
+  };
+}
+
+function checkForTransformError(file) {
+  const potentialError = file.contents.includes(transformErrorWarn);
+  if (potentialError) {
+    return {
+      ...vinyl.setTransformError(true, file)
+    };
+  }
+  return file;
+}
+
 export const babelTransformer = cond([
   [
     testJS$JSX,
     flow(
       partial(
         vinyl.transformHeadTailAndContents,
-        babelTransformCode
+        tryJSTransform(babelTransformCode, 'JSX')
       ),
-      partial(vinyl.setExt, 'js')
+      partial(vinyl.setExt, 'js'),
+      checkForTransformError
     )
   ],
   [ stubTrue, identity ]

common/app/routes/Challenges/redux/execute-challenge-epic.js

@@ -12,7 +12,8 @@ import {
 
   codeLockedSelector,
   showPreviewSelector,
-  testsSelector
+  testsSelector,
+  disableJSOnError
 } from './';
 import {
   buildFromFiles,
@@ -26,7 +27,8 @@ import {
 import {
   createErrorObservable,
 
-  challengeSelector
+  challengeSelector,
+  doActionOnError
 } from '../../../redux';
 
 
@@ -40,7 +42,6 @@ export function updateMainEpic(actions, { getState }, { document }) {
       const proxyLogger = new Subject();
       const frameMain = createMainFramer(document, getState, proxyLogger);
       const buildAndFrameMain = actions::ofType(
-        types.unlockUntrustedCode,
         types.modernEditorUpdated,
         types.classicEditorUpdated,
         types.executeChallenge,
@@ -55,7 +56,7 @@ export function updateMainEpic(actions, { getState }, { document }) {
         .flatMapLatest(() => buildFromFiles(getState(), true)
           .map(frameMain)
           .ignoreElements()
-          .catch(createErrorObservable)
+          .catch(doActionOnError(() => disableJSOnError()))
         );
       return Observable.merge(buildAndFrameMain, proxyLogger.map(updateOutput));
     });

common/app/routes/Challenges/redux/index.js

@@ -77,6 +77,7 @@ export const types = createTypes([
   'checkChallenge',
   createAsyncTypes('submitChallenge'),
   'moveToNextChallenge',
+  'disableJSOnError',
 
   // help
   'openHelpModal',
@@ -151,6 +152,8 @@ export const submitChallengeComplete = createAction(
 
 export const moveToNextChallenge = createAction(types.moveToNextChallenge);
 
+export const disableJSOnError = createAction(types.disableJSOnError);
+
 // help
 export const openHelpModal = createAction(types.openHelpModal);
 export const closeHelpModal = createAction(types.closeHelpModal);
@@ -306,6 +309,7 @@ export default combineReducers(
       [
         combineActions(
           types.classicEditorUpdated,
+          types.disableJSOnError,
           types.modernEditorUpdated
         )
       ]: state => ({

common/app/routes/Challenges/utils/build.js

@@ -42,6 +42,15 @@ const globalRequires = [
   jQuery
 ];
 
+function postTransformCheck(file) {
+  if (file.transformError) {
+    // this will enable us to tap into the dipatch pipeline
+    // and disable JS in the preview
+    throw new Error('There was an error whilst transforming your code');
+  }
+  return file;
+}
+
 export function buildFromFiles(state, shouldProxyConsole) {
   const files = filesSelector(state);
   const required = challengeRequiredSelector(state);
@@ -49,6 +58,7 @@ export function buildFromFiles(state, shouldProxyConsole) {
   return createFileStream(files)
     ::pipe(throwers)
     ::pipe(applyTransformers)
+    ::pipe(postTransformCheck)
     ::pipe(shouldProxyConsole ? proxyLoggerTransformer : identity)
     ::pipe(jsToHtml)
     ::pipe(cssToHtml)

common/utils/polyvinyl.js

@@ -77,7 +77,8 @@ export function createPoly({
     path: name + '.' + ext,
     key: name + ext,
     contents,
-    error: null
+    error: null,
+    transformError: false
   };
 }
 
@@ -116,7 +117,7 @@ export function setContent(contents, poly) {
   };
 }
 
-// setExt(contents: String, poly: PolyVinyl) => PolyVinyl
+// setExt(ext: String, poly: PolyVinyl) => PolyVinyl
 export function setExt(ext, poly) {
   checkPoly(poly);
   const newPoly = {
@@ -129,7 +130,7 @@ export function setExt(ext, poly) {
   return newPoly;
 }
 
-// setName(contents: String, poly: PolyVinyl) => PolyVinyl
+// setName(name: String, poly: PolyVinyl) => PolyVinyl
 export function setName(name, poly) {
   checkPoly(poly);
   const newPoly = {
@@ -142,7 +143,7 @@ export function setName(name, poly) {
   return newPoly;
 }
 
-// setError(contents: String, poly: PolyVinyl) => PolyVinyl
+// setError(error: Object, poly: PolyVinyl) => PolyVinyl
 export function setError(error, poly) {
   invariant(
     typeof error === 'object',
@@ -155,6 +156,19 @@ export function setError(error, poly) {
     error
   };
 }
+// setTransformError(transformError: Boolean, poly: PolyVinyl) => PolyVinyl
+export function setTransformError(transformError, poly) {
+  invariant(
+    typeof transformError === 'boolean',
+    'transformError must be a boolean, but got %',
+    transformError
+  );
+  checkPoly(poly);
+  return {
+    ...poly,
+    transformError
+  };
+}
 
 // clearHeadTail(poly: PolyVinyl) => PolyVinyl
 export function clearHeadTail(poly) {
@@ -166,6 +180,7 @@ export function clearHeadTail(poly) {
   };
 }
 
+// appendToTail (tail: String, poly: PolyVinyl) => PolyVinyl
 export function appendToTail(tail, poly) {
   checkPoly(poly);
   return {
@@ -174,7 +189,7 @@ export function appendToTail(tail, poly) {
   };
 }
 
-// compileHeadTail(contents: String, poly: PolyVinyl) => PolyVinyl
+// compileHeadTail(padding: String, poly: PolyVinyl) => PolyVinyl
 export function compileHeadTail(padding = '', poly) {
   return clearHeadTail(transformContents(
     () => [ poly.head, poly.contents, poly.tail ].join(padding),