Run snapshot tests based on storybook

This provides some additional assurance that PRs don't break aspects
of the UI. These are currently render-only, because the snapshot
output appears to be non-deterministic. Still, this should catch
some basic bugs.

.babelrc

@@ -3,7 +3,7 @@
     "@babel/preset-react",
     ["@babel/preset-env", { "targets": { "node": "current" } }]
   ],
-  "plugins": ["@babel/plugin-proposal-class-properties", "emotion"],
+  "plugins": ["@babel/plugin-proposal-class-properties", "emotion", "macros"],
   "env": {
     "test": {
       "plugins": ["@babel/plugin-transform-modules-commonjs", "emotion"]

.circleci/config.yml

@@ -36,6 +36,7 @@ jobs:
       - run: npm run build
       - run: npm run test-coverage -- --runInBand
       - run: bash <(curl -s https://codecov.io/bash) -f .coverage/coverage-final.json -Z
+      - run: npm run build-storybook
 
   build:
     docker:
@@ -92,8 +93,7 @@ jobs:
           name: Build docs
           command: mkdocs build
       - add_ssh_keys:
-          fingerprints:
-            "e2:81:9f:89:ea:24:ed:8a:da:a9:38:3b:61:bc:03:c9"
+          fingerprints: "e2:81:9f:89:ea:24:ed:8a:da:a9:38:3b:61:bc:03:c9"
       - deploy:
           name: Deploy
           command: |

.storybook/config.js

@@ -1,4 +1,5 @@
 import { configure, addParameters } from "@storybook/react";
+import requireContext from 'require-context.macro';
 
 addParameters({
   options: {
@@ -11,7 +12,7 @@ addParameters({
 });
 
 // automatically import all files ending in *.stories.js
-const req = require.context("../src", true, /\.stories\.js$/);
+const req = requireContext("../src", true, /\.stories\.js$/);
 function loadStories() {
   req.keys().forEach(filename => req(filename));
 }