Get ESLint rolling (#479)

* Prefer default export in eslint rules

* Add eslint to make test

Which eventually is run by travis.
Along with an eslintignore file for all exercises. We will fix and
enable eslint for each exercise.

* Upgrade eslint and remove unwanted eslint packages

eslint `jsx` and `react` packages are not required.

* Use airbnb-base instead of airbnb package

Since this is a plain JS repo (no react/JSX) - base is what we need.

* Fix hello-world exercise for eslint

To avoid fatal error on no files found:
https://eslint.org/docs/5.0.0/user-guide/migrating-to-5.0.0#nonexistent-files

In the process also change `hello-world` to not use `class`.

Author: tejasbubane

.eslintignore

@@ -0,0 +1,98 @@
+accumulate
+acronym
+all-your-base
+allergies
+alphametics
+anagram
+armstrong-numbers
+atbash-cipher
+beer-song
+binary
+binary-search
+binary-search-tree
+bob
+bowling
+bracket-push
+change
+circular-buffer
+clock
+collatz-conjecture
+complex-numbers
+connect
+crypto-square
+custom-set
+diamond
+difference-of-squares
+diffie-hellman
+etl
+flatten-array
+food-chain
+forth
+gigasecond
+grade-school
+grains
+hamming
+hexadecimal
+house
+isbn-verifier
+isogram
+kindergarten-garden
+largest-series-product
+leap
+linked-list
+list-ops
+luhn
+matrix
+meetup
+minesweeper
+nth-prime
+nucleotide-count
+ocr-numbers
+octal
+palindrome-products
+pangram
+pascals-triangle
+perfect-numbers
+phone-number
+pig-latin
+point-mutations
+prime-factors
+protein-translation
+proverb
+pythagorean-triplet
+queen-attack
+raindrops
+rational-numbers
+react
+rectangles
+reverse-string
+rna-transcription
+robot-name
+robot-simulator
+roman-numerals
+rotational-cipher
+run-length-encoding
+saddle-points
+say
+scrabble-score
+secret-handshake
+series
+sieve
+simple-cipher
+simple-linked-list
+space-age
+spiral-matrix
+strain
+sublist
+sum-of-multiples
+transpose
+triangle
+trinary
+twelve-days
+two-bucket
+two-fer
+variable-length-quantity
+word-count
+word-search
+wordy
+zipper

Makefile

@@ -36,11 +36,15 @@ test-travis:
 	@for pkg in $(PKG_FILES); do \
   		! ./bin/md5-hash $$pkg | grep -qv $(SOURCE_PKG_MD5) || { echo "$$pkg does not match main package.json.  Please run 'make test' locally and commit the results."; exit 1; }; \
   	done
-	@echo "Preparing tests..."
-	@for assignment in $(ASSIGNMENTS); do ASSIGNMENT=$$assignment $(MAKE) -s copy-assignment || exit 1; done
-	@node_modules/.bin/jest --bail $(OUTDIR)
-	@rm -rf $(OUTDIR)
+	$(MAKE) -s test
 
 test:
 	@echo "Preparing tests..."
-	@for assignment in $(ASSIGNMENTS); do ASSIGNMENT=$$assignment $(MAKE) -s copy-assignment || exit 1; node_modules/.bin/jest --bail $(OUTDIR); rm -rf $(OUTDIR); done
+	@for assignment in $(ASSIGNMENTS); do \
+		ASSIGNMENT=$$assignment $(MAKE) -s copy-assignment || exit 1; \
+	done
+	@echo "Checking eslint..."
+	@node_modules/.bin/eslint $(OUTDIR);
+	@echo "Running tests..."
+	@node_modules/.bin/jest --bail $(OUTDIR);
+	rm -rf $(OUTDIR);

exercises/accumulate/package.json

@@ -12,11 +12,9 @@
     "babel-jest": "^21.2.0",
     "babel-plugin-transform-builtin-extend": "^1.1.2",
     "babel-preset-env": "^1.4.0",
-    "eslint": "^3.19.0",
-    "eslint-config-airbnb": "^15.0.1",
-    "eslint-plugin-import": "^2.2.0",
-    "eslint-plugin-jsx-a11y": "^5.0.1",
-    "eslint-plugin-react": "^7.0.1",
+    "eslint": "^5.6.0",
+    "eslint-config-airbnb-base": "^13.1.0",
+    "eslint-plugin-import": "^2.14.0",
     "jest": "^21.2.1"
   },
   "jest": {
@@ -67,10 +65,12 @@
       "node": true,
       "jest": true
     },
-    "extends": "airbnb",
+    "extends": "airbnb-base",
     "rules": {
       "import/no-unresolved": "off",
-      "import/extensions": "off"
+      "import/extensions": "off",
+      "import/prefer-default-export": "off",
+      "import/no-default-export": "off"
     }
   },
   "licenses": [

exercises/acronym/package.json

@@ -12,11 +12,9 @@
     "babel-jest": "^21.2.0",
     "babel-plugin-transform-builtin-extend": "^1.1.2",
     "babel-preset-env": "^1.4.0",
-    "eslint": "^3.19.0",
-    "eslint-config-airbnb": "^15.0.1",
-    "eslint-plugin-import": "^2.2.0",
-    "eslint-plugin-jsx-a11y": "^5.0.1",
-    "eslint-plugin-react": "^7.0.1",
+    "eslint": "^5.6.0",
+    "eslint-config-airbnb-base": "^13.1.0",
+    "eslint-plugin-import": "^2.14.0",
     "jest": "^21.2.1"
   },
   "jest": {
@@ -67,10 +65,12 @@
       "node": true,
       "jest": true
     },
-    "extends": "airbnb",
+    "extends": "airbnb-base",
     "rules": {
       "import/no-unresolved": "off",
-      "import/extensions": "off"
+      "import/extensions": "off",
+      "import/prefer-default-export": "off",
+      "import/no-default-export": "off"
     }
   },
   "licenses": [

exercises/all-your-base/package.json

@@ -12,11 +12,9 @@
     "babel-jest": "^21.2.0",
     "babel-plugin-transform-builtin-extend": "^1.1.2",
     "babel-preset-env": "^1.4.0",
-    "eslint": "^3.19.0",
-    "eslint-config-airbnb": "^15.0.1",
-    "eslint-plugin-import": "^2.2.0",
-    "eslint-plugin-jsx-a11y": "^5.0.1",
-    "eslint-plugin-react": "^7.0.1",
+    "eslint": "^5.6.0",
+    "eslint-config-airbnb-base": "^13.1.0",
+    "eslint-plugin-import": "^2.14.0",
     "jest": "^21.2.1"
   },
   "jest": {
@@ -67,10 +65,12 @@
       "node": true,
       "jest": true
     },
-    "extends": "airbnb",
+    "extends": "airbnb-base",
     "rules": {
       "import/no-unresolved": "off",
-      "import/extensions": "off"
+      "import/extensions": "off",
+      "import/prefer-default-export": "off",
+      "import/no-default-export": "off"
     }
   },
   "licenses": [

exercises/allergies/package.json

@@ -12,11 +12,9 @@
     "babel-jest": "^21.2.0",
     "babel-plugin-transform-builtin-extend": "^1.1.2",
     "babel-preset-env": "^1.4.0",
-    "eslint": "^3.19.0",
-    "eslint-config-airbnb": "^15.0.1",
-    "eslint-plugin-import": "^2.2.0",
-    "eslint-plugin-jsx-a11y": "^5.0.1",
-    "eslint-plugin-react": "^7.0.1",
+    "eslint": "^5.6.0",
+    "eslint-config-airbnb-base": "^13.1.0",
+    "eslint-plugin-import": "^2.14.0",
     "jest": "^21.2.1"
   },
   "jest": {
@@ -67,10 +65,12 @@
       "node": true,
       "jest": true
     },
-    "extends": "airbnb",
+    "extends": "airbnb-base",
     "rules": {
       "import/no-unresolved": "off",
-      "import/extensions": "off"
+      "import/extensions": "off",
+      "import/prefer-default-export": "off",
+      "import/no-default-export": "off"
     }
   },
   "licenses": [

exercises/alphametics/package.json

@@ -12,11 +12,9 @@
     "babel-jest": "^21.2.0",
     "babel-plugin-transform-builtin-extend": "^1.1.2",
     "babel-preset-env": "^1.4.0",
-    "eslint": "^3.19.0",
-    "eslint-config-airbnb": "^15.0.1",
-    "eslint-plugin-import": "^2.2.0",
-    "eslint-plugin-jsx-a11y": "^5.0.1",
-    "eslint-plugin-react": "^7.0.1",
+    "eslint": "^5.6.0",
+    "eslint-config-airbnb-base": "^13.1.0",
+    "eslint-plugin-import": "^2.14.0",
     "jest": "^21.2.1"
   },
   "jest": {
@@ -67,10 +65,12 @@
       "node": true,
       "jest": true
     },
-    "extends": "airbnb",
+    "extends": "airbnb-base",
     "rules": {
       "import/no-unresolved": "off",
-      "import/extensions": "off"
+      "import/extensions": "off",
+      "import/prefer-default-export": "off",
+      "import/no-default-export": "off"
     }
   },
   "licenses": [

exercises/anagram/package.json

@@ -12,11 +12,9 @@
     "babel-jest": "^21.2.0",
     "babel-plugin-transform-builtin-extend": "^1.1.2",
     "babel-preset-env": "^1.4.0",
-    "eslint": "^3.19.0",
-    "eslint-config-airbnb": "^15.0.1",
-    "eslint-plugin-import": "^2.2.0",
-    "eslint-plugin-jsx-a11y": "^5.0.1",
-    "eslint-plugin-react": "^7.0.1",
+    "eslint": "^5.6.0",
+    "eslint-config-airbnb-base": "^13.1.0",
+    "eslint-plugin-import": "^2.14.0",
     "jest": "^21.2.1"
   },
   "jest": {
@@ -67,10 +65,12 @@
       "node": true,
       "jest": true
     },
-    "extends": "airbnb",
+    "extends": "airbnb-base",
     "rules": {
       "import/no-unresolved": "off",
-      "import/extensions": "off"
+      "import/extensions": "off",
+      "import/prefer-default-export": "off",
+      "import/no-default-export": "off"
     }
   },
   "licenses": [

exercises/armstrong-numbers/package.json

@@ -12,11 +12,9 @@
     "babel-jest": "^21.2.0",
     "babel-plugin-transform-builtin-extend": "^1.1.2",
     "babel-preset-env": "^1.4.0",
-    "eslint": "^3.19.0",
-    "eslint-config-airbnb": "^15.0.1",
-    "eslint-plugin-import": "^2.2.0",
-    "eslint-plugin-jsx-a11y": "^5.0.1",
-    "eslint-plugin-react": "^7.0.1",
+    "eslint": "^5.6.0",
+    "eslint-config-airbnb-base": "^13.1.0",
+    "eslint-plugin-import": "^2.14.0",
     "jest": "^21.2.1"
   },
   "jest": {
@@ -67,10 +65,12 @@
       "node": true,
       "jest": true
     },
-    "extends": "airbnb",
+    "extends": "airbnb-base",
     "rules": {
       "import/no-unresolved": "off",
-      "import/extensions": "off"
+      "import/extensions": "off",
+      "import/prefer-default-export": "off",
+      "import/no-default-export": "off"
     }
   },
   "licenses": [

exercises/atbash-cipher/package.json

@@ -12,11 +12,9 @@
     "babel-jest": "^21.2.0",
     "babel-plugin-transform-builtin-extend": "^1.1.2",
     "babel-preset-env": "^1.4.0",
-    "eslint": "^3.19.0",
-    "eslint-config-airbnb": "^15.0.1",
-    "eslint-plugin-import": "^2.2.0",
-    "eslint-plugin-jsx-a11y": "^5.0.1",
-    "eslint-plugin-react": "^7.0.1",
+    "eslint": "^5.6.0",
+    "eslint-config-airbnb-base": "^13.1.0",
+    "eslint-plugin-import": "^2.14.0",
     "jest": "^21.2.1"
   },
   "jest": {
@@ -67,10 +65,12 @@
       "node": true,
       "jest": true
     },
-    "extends": "airbnb",
+    "extends": "airbnb-base",
     "rules": {
       "import/no-unresolved": "off",
-      "import/extensions": "off"
+      "import/extensions": "off",
+      "import/prefer-default-export": "off",
+      "import/no-default-export": "off"
     }
   },
   "licenses": [