Add an eslint rule for import file extensions (#438)

Author: patrick-tolosa

.eslintrc

@@ -2,7 +2,8 @@
   "root": true,
   "parser": "@typescript-eslint/parser",
   "plugins": [
-    "@typescript-eslint"
+    "@typescript-eslint",
+    "import"
   ],
   "extends": [
     "eslint:recommended",
@@ -35,6 +36,7 @@
     "comma-spacing" : "error",
     "no-multi-spaces" : "error",
     "prefer-template" : "error",
+    "import/extensions": [2, "ignorePackages"],
     "max-nested-callbacks" : ["error",{
       "max": 3
     }],

package.json

@@ -22,7 +22,9 @@
     "build:copyCleanPackageJSON": "ts-node scripts/copyPackageJsonToSrc.ts",
     "build:injectPackageVersion": "ts-node ./scripts/injectPackageVersionToDistFiles.ts",
     "build:updatePackageExports": "ts-node scripts/updatePackageJsonExports.ts",
-    "lint": "eslint src __TESTS__ --color --ext .ts",
+    "lint": "npm run lint:src && npm run lint:test",
+    "lint:src" : "eslint src --color --ext .ts",
+    "lint:test": "eslint __TESTS__ __TESTS_BUNDLE_SIZE__ --rule 'import/extensions: [0, \"never\"]' --color --ext .ts",
     "start": "rollup -c rollup.dev.config.js -w",
     "bundlewatch": "bundlewatch --config ./bundlewatch.config.js",
     "release-dry-run": "npm run build && cp README.md LICENSE ./dist && cd ./dist && release-it --dry-run",
@@ -52,6 +54,7 @@
     "clipboard": "2.0.1",
     "cloudinary-core": "^2.11.4",
     "eslint": "^6.8.0",
+    "eslint-plugin-import": "^2.24.2",
     "extend": "^3.0.1",
     "glob": "^7.1.2",
     "grunt": "^1.0.2",
@@ -112,4 +115,4 @@
       "default": "./index.js"
     }
   }
-}
+}