Improve eslint rules and run them from CI

.eslintrc.js

@@ -33,14 +33,22 @@ module.exports = {
 	    "sourceType": "module",
 	},
 	'rules': {
+		// -------------------------------
+		// Code correctness
+		// -------------------------------
 		"react/jsx-uses-react": "error",
 		"react/jsx-uses-vars": "error",
-		// Ignore all unused function arguments, because in some
-		// case they are kept to indicate the function signature.
-		//"no-unused-vars": ["error", { "argsIgnorePattern": ".*" }],
-		"@typescript-eslint/no-unused-vars": ["error"],
+		"no-unused-vars": "error",
 		"no-constant-condition": 0,
 		"no-prototype-builtins": 0,
+		// This error is always a false positive so far since it detects
+		// possible race conditions in contexts where we know it cannot happen.
+		"require-atomic-updates": 0,
+		"no-lonely-if": "error",
+
+		// -------------------------------
+		// Formatting
+		// -------------------------------
 		"space-in-parens": ["error", "never"],
 		"semi": ["error", "always"],
 		"eol-last": ["error", "always"],
@@ -49,11 +57,19 @@ module.exports = {
 		"comma-dangle": ["error", "always-multiline"],
 		"no-trailing-spaces": "error",
 		"linebreak-style": ["error", "unix"],
-		// This error is always a false positive so far since it detects
-		// possible race conditions in contexts where we know it cannot happen.
-		"require-atomic-updates": 0,
 		"prefer-template": ["error"],
-		"template-curly-spacing": ["error", "never"]
+		"template-curly-spacing": ["error", "never"],
+		"key-spacing": ["error", {
+			"beforeColon": false,
+			"afterColon": true,
+			"mode": "strict"
+		}],
+		"block-spacing": ["error"],
+		"brace-style": ["error", "1tbs"],
+		"no-spaced-func": ["error"],
+		"func-call-spacing": ["error"],
+		"space-before-function-paren": ["error", "never"],
+		"object-property-newline": ["error"]
 	},
 	"plugins": [
 		"react",

.travis.yml

@@ -55,17 +55,30 @@ before_install:
 script:
   - |
     # Install tools
+    npm install
     cd Tools
     npm install
+    cd ..
 
     # Run test units
-    cd ../CliClient
+    cd CliClient
     npm install
     ./run_test.sh
     testResult=$?
     if [ $testResult -ne 0 ]; then
       exit $testResult
     fi
+    cd ..
+
+    # Run linter for pull requests only - this is so that
+    # bypassing eslint is allowed for urgent fixes.
+    if [ "$TRAVIS_PULL_REQUEST" != "false" ]; then
+      npm run linter-ci ./
+      testResult=$?
+      if [ $testResult -ne 0 ]; then
+        exit $testResult
+      fi
+    fi
 
     # Find out if we should run the build or not. Electron-builder gets stuck when
     # builing PRs so we disable it in this case. The Linux build should provide
@@ -78,6 +91,6 @@ script:
     fi
 
     # Prepare the Electron app and build it
-    cd ../ElectronClient/app
+    cd ElectronClient/app
     rsync -aP --delete ../../ReactNativeClient/lib/ lib/
     npm install && USE_HARD_LINKS=false yarn dist

package.json

@@ -3,7 +3,8 @@
   "version": "1.0.0",
   "description": "Joplin root package for linting",
   "scripts": {
-    "linter": "./node_modules/.bin/eslint --fix --ext .js --ext .jsx"
+    "linter": "./node_modules/.bin/eslint --fix --ext .js --ext .jsx",
+    "linter-ci": "./node_modules/.bin/eslint --ext .js --ext .jsx"
   },
   "husky": {
     "hooks": {