add and use MockFetchApi

Signed-off-by: Fredrik Adelöw <freben@gmail.com>

packages/test-utils/package.json

@@ -41,6 +41,7 @@
     "@testing-library/jest-dom": "^5.10.1",
     "@testing-library/react": "^11.2.5",
     "@testing-library/user-event": "^13.1.8",
+    "cross-fetch": "^3.0.6",
     "react-router": "6.0.0-beta.0",
     "react-router-dom": "6.0.0-beta.0",
     "zen-observable": "^0.8.15"
@@ -52,7 +53,8 @@
   "devDependencies": {
     "@backstage/cli": "^0.12.0-next.0",
     "@types/jest": "^26.0.7",
-    "@types/node": "^14.14.32"
+    "@types/node": "^14.14.32",
+    "msw": "^0.35.0"
   },
   "files": [
     "dist"