[Frontend] unit tests for node server (kubeflow#2745)

* Add unit tests for aws-helper and minio-helper.

* Break up server.ts into app.ts and handlers/*.ts so that unit test can be written more easily.

* update @types/node because of microsoft/TypeScript#32333

* upgrade kubernete-client version to be compatible with new @types/node version

* fix bug: AWSInstanceProfileCredentials.profile() returns a promise not a string

* remove I prefix from interfaces. minor fixes on lint errors.

* fix format errors

* Added more unit tests, and minor fixes.

* Fix comment: GKS should be GKE

* use jest.resetAllMocks instead of reset each mock individually

* fix format for helper test

Author: eterna2

frontend/.gitignore

@@ -24,3 +24,9 @@ backstop_data/bitmaps_test/
 npm-debug.log*
 yarn-debug.log*
 yarn-error.log*
+
+# coverage reports
+coverage
+
+# vscode
+.vscode

frontend/package-lock.json

@@ -55,9 +55,10 @@
     "start:proxy-standalone-and-server": "./start-proxy-standalone-and-server.sh",
     "start": "react-scripts-ts start",
     "test": "react-scripts-ts test --env=jsdom",
+    "test:server": "cd ./server && npm test && cd ..",
     "test:coverage": "npm test -- --env=jsdom --coverage",
     "test:ci": "npm run format:check && npm run lint && npm run test:coverage",
-    "test:ci:prow": "npm set unsafe-perm true && npm ci && npm run test:ci && ./scripts/report-coveralls.sh",
+    "test:ci:prow": "npm set unsafe-perm true && npm ci && npm run test:ci && ./scripts/report-coveralls.sh && npm run test:server",
     "vr-approve": "backstop approve",
     "vr-test": "ts-node -O '{\"module\": \"commonjs\"}' backstop.ts"
   },
@@ -74,7 +75,7 @@
     "@types/js-yaml": "^3.11.2",
     "@types/lodash": ">=4.14.117",
     "@types/markdown-to-jsx": "^6.9.0",
-    "@types/node": "^10.10.1",
+    "@types/node": "^10.17.11",
     "@types/react": "^16.7.18",
     "@types/react-dom": "^16.0.7",
     "@types/react-router-dom": "^4.3.1",