Reinstated dependencies for Unit Testing, after latest merge from upstream branch

package.json

@@ -7,13 +7,14 @@
   "scripts": {
     "lint": "eslint .",
     "lint:fix": "eslint --fix .",
+    "prebuild": "npm run test",
     "build": "gatsby build",
     "develop": "gatsby develop",
     "format": "prettier --write \"**/*.{js,jsx,ts,tsx,json,md}\"",
     "start": "npm run develop",
     "serve": "gatsby serve",
     "clean": "gatsby clean",
-    "test": "echo \"Write tests! -> https://gatsby.dev/unit-testing\" && exit 1"
+    "test": "jest"
   },
   "dependencies": {
     "@material-ui/core": "^4.11.2",
@@ -61,6 +62,10 @@
     "yup": "^0.32.1"
   },
   "devDependencies": {
+    "@testing-library/jest-dom": "^5.11.6",
+    "@testing-library/react": "^11.2.2",
+    "babel-jest": "^26.6.3",
+    "babel-preset-gatsby": "^0.8.0",
     "eslint": "^7.15.0",
     "eslint-config-airbnb": "^18.2.1",
     "eslint-config-prettier": "^6.15.0",
@@ -69,6 +74,8 @@
     "eslint-plugin-prettier": "^3.2.0",
     "eslint-plugin-react": "^7.21.5",
     "gatsby-plugin-eslint": "^2.0.8",
+    "identity-obj-proxy": "^3.0.0",
+    "jest": "^26.6.3",
     "prettier": "2.2.1",
     "stylelint": "^13.8.0",
     "stylelint-config-standard": "^20.0.0",