build: integrate eslint

.eslintrc.js

@@ -0,0 +1,23 @@
+module.exports = {
+  // Common settings for JS Files.
+  extends: [
+    "eslint:recommended",
+    "plugin:eslint-comments/recommended",
+    // Disables all formatting related rules as formatting is handled by prettier, not eslint.
+    "prettier",
+  ],
+  parserOptions: {
+    // Targeting modern nodejs versions
+    // Consult with: https://kangax.github.io/compat-table/es2016plus/
+    ecmaVersion: 2018,
+  },
+  env: {
+    commonjs: true,
+    mocha: true,
+    node: true,
+    es6: true,
+  },
+  rules: {
+    "eslint-comments/require-description": ["error", { ignore: [] }],
+  },
+};

package.json

@@ -14,9 +14,11 @@
     "lerna:version": "lerna version && yarn run cirlce:release",
     "cirlce:release": "node ./scripts/trigger-release",
     "lerna:publish": "lerna publish from-git --yes",
-    "ci": "npm-run-all format:validate ci:subpackages coverage:merge legal:*",
+    "ci": "npm-run-all format:validate lint:validate ci:subpackages coverage:merge legal:*",
     "format:fix": "prettier --write --ignore-path .gitignore \"**/*.@(ts|js|json|md)\"",
     "format:validate": "prettier --check --ignore-path .gitignore \"**/*.@(ts|js|json|md)\"",
+    "lint:fix": "eslint . --ext=js --fix --max-warnings=0 --ignore-path=.gitignore",
+    "lint:validate": "eslint . --ext=js --max-warnings=0 --ignore-path=.gitignore",
     "ci:subpackages": "lerna run ci",
     "test": "lerna run test",
     "coverage": "lerna run coverage",
@@ -29,6 +31,9 @@
     "@types/chai": "4.2.11",
     "@types/mocha": "7.0.2",
     "@types/node": "10.17.15",
+    "eslint": "7.9.0",
+    "eslint-config-prettier": "6.15.0",
+    "eslint-plugin-eslint-comments": "3.2.0",
     "coveralls": "3.1.0",
     "make-dir": "3.1.0",
     "glob": "7.1.6",
@@ -64,6 +69,9 @@
   "lint-staged": {
     "*.{ts,js,md,json}": [
       "prettier --write"
+    ],
+    "*.{ts,js}": [
+      "eslint --fix --max-warnings=0 --ignore-pattern=!.*"
     ]
   },
   "config": {

packages/ast/lib/build-ast.js

@@ -34,6 +34,7 @@ function buildAst(docCst, tokenVector) {
   return xmlDocAst;
 }
 
+/* eslint-disable no-unused-vars -- consistent signatures in visitor methods even if they are empty placeholders */
 class CstToAstVisitor extends BaseXmlCstVisitor {
   constructor() {
     super();
@@ -253,6 +254,7 @@ class CstToAstVisitor extends BaseXmlCstVisitor {
     // Irrelevant for the AST at this time
   }
 }
+/* eslint-enable no-unused-vars -- see matching disable comment */
 
 const AstBuilder = new CstToAstVisitor();
 

packages/ast/lib/utils.js

@@ -1,4 +1,4 @@
-const { values, reduce, has, isArray } = require("lodash");
+const { reduce, has, isArray } = require("lodash");
 
 function getAstChildrenReflective(astParent) {
   const astChildren = reduce(

packages/ast/test/utils.js

@@ -10,14 +10,11 @@ function modifyAstForAssertions(astNode) {
   accept(astNode, positionReducerVisitor);
 }
 
-function removeParentProps(astNode) {
-  accept(astNode, parentRemoverVisitor);
-}
-
 /**
  * @type {XMLAstVisitor}
  */
 const parentRemoverVisitor = {
+  /* eslint-disable-next-line no-unused-vars -- consistent signatures in visitor methods even if they are empty placeholders */
   visitXMLDocument: (node) => {
     // top level XML Doc does not have a parent...
   },
@@ -85,6 +82,7 @@ function assertParentPropsAreValid(astNode) {
  * @type {XMLAstVisitor}
  */
 const parentPropsValidatorVisitor = {
+  /* eslint-disable-next-line no-unused-vars -- consistent signatures in visitor methods even if they are empty placeholders */
   visitXMLDocument: (node) => {
     // top level XML Doc does not have a parent...
   },

packages/content-assist/lib/content-assist.js

@@ -30,6 +30,7 @@ function computeCompletionSyntacticContext({
   return contextVisitor.result;
 }
 
+/* eslint-disable no-unused-vars -- consistent signatures in visitor methods even if they are empty placeholders */
 class SuggestionContextVisitor extends BaseXmlCstVisitor {
   constructor(docAst, offset, tokenVector) {
     super();
@@ -171,6 +172,7 @@ class SuggestionContextVisitor extends BaseXmlCstVisitor {
   /* istanbul ignore next - place holder*/
   misc(ctx, astNode) {}
 }
+/* eslint-enable no-unused-vars -- see matching pair above */
 
 function handleElementNameWithoutPrefixScenario(ctx, astNode, visitor) {
   /* istanbul ignore else - Very difficult to reproduce specific partial CSTs */

packages/content-assist/test/scenarios-spec.js

@@ -117,6 +117,7 @@ describe("The XML Content Assist Capabilities", () => {
         let providerCalled = false;
         getSampleSuggestions(sample, {
           elementContent: [
+            // eslint-disable-next-line no-unused-vars -- match the type of `ElementContentCompletion` for consistency
             ({ element }) => {
               providerCalled = true;
             },

packages/parser/lib/parser.js

@@ -184,10 +184,11 @@ class Parser extends CstParser {
   // https://github.com/SAP/chevrotain/issues/1055
   /* istanbul ignore next - should be tested as part of Chevrotain */
   findReSyncTokenType() {
-    var allPossibleReSyncTokTypes = this.flattenFollowSet();
+    const allPossibleReSyncTokTypes = this.flattenFollowSet();
     // this loop will always terminate as EOF is always in the follow stack and also always (virtually) in the input
     let nextToken = this.LA(1);
     let k = 2;
+    /* eslint-disable-next-line no-constant-condition -- see above comment */
     while (true) {
       const foundMatch = allPossibleReSyncTokTypes.find((resyncTokType) => {
         const canMatch = tokenMatcher(nextToken, resyncTokType);

packages/simple-schema/lib/content-assist/attribute-name.js

@@ -1,12 +1,12 @@
-const { difference, map, filter } = require("lodash");
+const { difference, map } = require("lodash");
 
 /**
  * @param {XMLElement} elementNode
  * @param {XSSElement} xssElement
  *
  * @returns {CompletionSuggestion[]}
  */
-function attributeNameCompletion(elementNode, xssElement, prefix = "") {
+function attributeNameCompletion(elementNode, xssElement) {
   const possibleSuggestions = map(xssElement.attributes, (_) => _.key);
   const existingAttribNames = map(elementNode.attributes, (_) => _.key);
   const possibleNewSuggestions = difference(

packages/simple-schema/lib/content-assist/element-name.js

@@ -46,24 +46,21 @@ function elementNameCompletion(elementNode, xssElement, prefix = "") {
       elementNode.namespaces,
       (uri, prefix) => prefix !== DEFAULT_NS
     );
-    const applicableNamespaces = pickBy(
-      namespacesWithoutDefault,
-      (uri, prefix) => {
-        const possibleElements = filter(
-          xssElement.elements,
-          (element) =>
-            has(element, "namespace") === true && element.namespace === uri
-        );
-        const possibleSuggestionsWithoutExistingSingular = applicableElements(
-          xssElement.elements,
-          elementNode.subElements,
-          possibleElements
-        );
-        const namespaceHasApplicableElements =
-          possibleSuggestionsWithoutExistingSingular.length > 0;
-        return namespaceHasApplicableElements;
-      }
-    );
+    const applicableNamespaces = pickBy(namespacesWithoutDefault, (uri) => {
+      const possibleElements = filter(
+        xssElement.elements,
+        (element) =>
+          has(element, "namespace") === true && element.namespace === uri
+      );
+      const possibleSuggestionsWithoutExistingSingular = applicableElements(
+        xssElement.elements,
+        elementNode.subElements,
+        possibleElements
+      );
+      const namespaceHasApplicableElements =
+        possibleSuggestionsWithoutExistingSingular.length > 0;
+      return namespaceHasApplicableElements;
+    });
     const namespaceSuggestions = map(applicableNamespaces, (uri, prefix) => ({
       text: prefix,
       label: prefix,
@@ -87,10 +84,11 @@ function applicableElements(xssElements, subElements, possibleElements) {
   const notSingularElemNames = map(notSingularElem, (element) => element.name);
   const existingElemNames = map(subElements, (element) => element.name);
   const existingSingular = difference(existingElemNames, notSingularElemNames);
-  return (possibleSuggestionsWithoutExistingSingular = difference(
+  const possibleSuggestionsWithoutExistingSingular = difference(
     allPossibleSuggestions,
     existingSingular
-  ));
+  );
+  return possibleSuggestionsWithoutExistingSingular;
 }
 
 module.exports = {