Add "fetch" polyfill for tests (not working, issue with jest setupFilesAfterEnv being empty regardless of package.json:jest config)

Author: Vadorequest

jest.setup.js

@@ -0,0 +1,11 @@
+import fetch from 'node-fetch';
+
+/**
+ * @see https://github.com/vercel/next.js/discussions/13678 How to use built-in fetch in tests?
+ * @see https://nextjs.org/blog/next-9-4#improved-built-in-fetch-support Next.js Blog - Improved Built-in Fetch Support
+ * @see https://jestjs.io/docs/en/configuration#setupfilesafterenv-array About setupFilesAfterEnv usage
+ */
+// Polyfill "fetch" for node.js, so that our tests may replicate the built-in "fetch" provided by Next.js
+global.fetch = fetch;
+
+console.info('Jest env has been enhanced - See "./jest.setup.js"')

package.json

@@ -40,12 +40,14 @@
     "test": "NODE_ENV=test jest --watchAll",
     "test:once": "NODE_ENV=test jest",
     "test:coverage": "NODE_ENV=test jest --coverage",
+    "test:config": "NODE_ENV=test jest --showConfig",
     "security:audit": "yarn audit",
     "packages:upgrade": "yarn upgrade-interactive --latest"
   },
   "jest": {
     "setupFilesAfterEnv": [
-      "jest-extended"
+      "jest-extended",
+      "./jest.setup.js"
     ]
   },
   "dependencies": {
@@ -128,6 +130,7 @@
     "@types/lodash.some": "4.6.6",
     "@types/lodash.startswith": "4.2.6",
     "@types/lodash.xorby": "4.7.6",
+    "@types/node-fetch": "2.5.7",
     "@types/popper.js": "1.11.0",
     "@types/react": "16.9.35",
     "@types/reactstrap": "8.4.2",
@@ -149,6 +152,7 @@
     "eslint-watch": "6.0.1",
     "jest": "26.0.1",
     "jest-extended": "0.11.5",
+    "node-fetch": "2.6.0",
     "node-mocks-http": "1.8.1",
     "now": "17.1.1",
     "react-test-renderer": "16.13.1",

yarn.lock

@@ -2146,6 +2146,14 @@
   resolved "https://registry.yarnpkg.com/@types/mocha/-/mocha-5.2.7.tgz#315d570ccb56c53452ff8638738df60726d5b6ea"
   integrity sha512-NYrtPht0wGzhwe9+/idPaBB+TqkY9AhTvOLMkThm0IoEfLaiVQZwBwyJ5puCkO3AUCWrmcoePjp2mbFocKy4SQ==
 
+"@types/[email protected]":
+  version "2.5.7"
+  resolved "https://registry.yarnpkg.com/@types/node-fetch/-/node-fetch-2.5.7.tgz#20a2afffa882ab04d44ca786449a276f9f6bbf3c"
+  integrity sha512-o2WVNf5UhWRkxlf6eq+jMZDu7kjgpgJfl4xVNlvryc95O/6F2ld8ztKX+qu+Rjyet93WAWm5LjeX9H5FGkODvw==
+  dependencies:
+    "@types/node" "*"
+    form-data "^3.0.0"
+
 "@types/node@*":
   version "13.7.6"
   resolved "https://registry.yarnpkg.com/@types/node/-/node-13.7.6.tgz#cb734a7c191472ae6a2b3a502b4dfffcea974113"
@@ -3825,7 +3833,7 @@ [email protected]:
     color "3.0.x"
     text-hex "1.0.x"
 
-combined-stream@^1.0.6, combined-stream@~1.0.6:
+combined-stream@^1.0.6, combined-stream@^1.0.8, combined-stream@~1.0.6:
   version "1.0.8"
   resolved "https://registry.yarnpkg.com/combined-stream/-/combined-stream-1.0.8.tgz#c3d45a8b34fd730631a110a8a2520682b31d5a7f"
   integrity sha512-FQN4MRfuJeHf7cBbBMJFXhKSDq+2kAArBlmRBvcvFE5BB1HZKXtSFASDhdlz9zOYwxh8lDdnvmMOe/+5cdoEdg==
@@ -5657,6 +5665,15 @@ [email protected]:
     tapable "^1.0.0"
     worker-rpc "^0.1.0"
 
+form-data@^3.0.0:
+  version "3.0.0"
+  resolved "https://registry.yarnpkg.com/form-data/-/form-data-3.0.0.tgz#31b7e39c85f1355b7139ee0c647cf0de7f83c682"
+  integrity sha512-CKMFDglpbMi6PyN+brwB9Q/GOw0eAnsrEZDgcsH5Krhz5Od/haKHAX0NmQfha2zPPz0JpWzA7GJHGSnvCRLWsg==
+  dependencies:
+    asynckit "^0.4.0"
+    combined-stream "^1.0.8"
+    mime-types "^2.1.12"
+
 form-data@~2.3.2:
   version "2.3.3"
   resolved "https://registry.yarnpkg.com/form-data/-/form-data-2.3.3.tgz#dcce52c05f644f298c6a7ab936bd724ceffbf3a6"