feat: add TypeScript type-checking to JavaScript files and export typ…

…e declarations (#723)

.eslintrc.js

@@ -44,5 +44,13 @@ module.exports = {
         'unicorn/filename-case': 'off',
       },
     },
+    {
+      parser: '@typescript-eslint/parser',
+      files: ['*.ts'],
+      extends: ['plugin:@typescript-eslint/recommended'],
+      rules: {
+        'node/no-unsupported-features/es-syntax': 'off',
+      },
+    },
   ],
 };

.gitignore

@@ -11,3 +11,6 @@ node_modules
 
 # eslint
 .eslintcache
+
+# TypeScript output
+dist/

lib/rules/no-assert-ok-find.js

@@ -1,6 +1,5 @@
 'use strict';
 
-const isMemberExpression = require('../utils/is-member-expression');
 const isTestFile = require('../utils/is-test-file');
 const { ReferenceTracker } = require('eslint-utils');
 
@@ -36,7 +35,17 @@ module.exports = {
 
         for (const { node } of tracker.iterateGlobalReferences(traceMap)) {
           const parentNode = node.parent;
-          if (isAssertOk(parentNode)) {
+          if (
+            // Check for assert.ok(...)
+            parentNode.type === 'CallExpression' &&
+            parentNode.callee.type === 'MemberExpression' &&
+            parentNode.callee.object.type === 'Identifier' &&
+            parentNode.callee.object.name === 'assert' &&
+            parentNode.callee.property.type === 'Identifier' &&
+            parentNode.callee.property.name === 'ok' &&
+            (parentNode.arguments.length === 1 ||
+              parentNode.arguments.length === 2)
+          ) {
             context.report({
               node: parentNode,
               messageId: 'error',
@@ -68,13 +77,3 @@ module.exports = {
     };
   },
 };
-
-function isAssertOk(node) {
-  return (
-    node.type === 'CallExpression' &&
-    isMemberExpression(node.callee) &&
-    node.callee.object.name === 'assert' &&
-    node.callee.property.name === 'ok' &&
-    (node.arguments.length === 1 || node.arguments.length === 2)
-  );
-}

lib/rules/no-handlebar-interpolation.js

@@ -37,6 +37,7 @@ module.exports = {
     // Defaults to anything `*.js`
     const defaultFilePattern = /\.js$/;
     // Only run on files that match filePatterns.
+    /** @type {{filePatterns: RegExp[]}} */
     const { filePatterns = [defaultFilePattern] } = context.options[0] || {};
     const matchesFilename = filePatterns.some((pattern) => {
       return pattern.test(context.getFilename());
@@ -46,6 +47,9 @@ module.exports = {
       return {};
     }
 
+    /**
+     * @param {import('estree').Literal} node
+     */
     function checkNode(node) {
       const { value } = node;
       if (typeof value === 'string' && tripleStashRegex.test(value)) {

lib/rules/no-missing-tests.js

@@ -44,7 +44,9 @@ module.exports = {
     },
   },
   create(context) {
-    const matchingLocation = context.options[0].find((location) =>
+    /** @type {{filePath:string,testPaths:string[],hasTestSuffix?:boolean}[]} */
+    const config = context.options[0];
+    const matchingLocation = config.find((location) =>
       context.getFilename().includes(location.filePath)
     );
 

lib/rules/no-restricted-files.js

@@ -40,12 +40,15 @@ module.exports = {
   create(context) {
     return {
       Program(node) {
-        const match = context.options.find((option) =>
+        /** @type {{message?:string,paths:string[]}[]} */
+        const config = context.options;
+        const match = config.find((option) =>
           option.paths.some((path) => context.getFilename().match(path))
         );
         if (match) {
           context.report({
             node,
+            // @ts-ignore -- `messageId` is optional.
             messageId: match.message ? undefined : 'defaultError',
             message: match.message, // eslint-disable-line eslint-plugin/prefer-message-ids
             // Uncomment this autofixer to grandfather in existing files.

lib/rules/no-test-return-value.js

@@ -22,7 +22,7 @@ const DEFAULT_TEST_HOOKS = [
   'todo',
 ];
 
-/** @type {import('eslint').Rule.RuleModule} */
+/** @type {import('eslint').Rule.RuleModule & { DEFAULT_TEST_HOOKS: string[] }} */
 module.exports = {
   DEFAULT_TEST_HOOKS,
   meta: {
@@ -80,6 +80,11 @@ module.exports = {
               {
                 messageId: 'suggest',
                 fix(fixer) {
+                  if (!node.range || !node.argument || !node.argument.range) {
+                    throw new Error(
+                      'This is just to make TypeScript happy. Every node should have a range and we already checked that the node has an argument.'
+                    );
+                  }
                   return fixer.removeRange([
                     node.range[0],
                     node.argument.range[0],
@@ -94,6 +99,9 @@ module.exports = {
   },
 };
 
+/**
+ * @param {import('eslint').Rule.RuleContext} context
+ */
 function getTestHooks(context) {
   return context.options && context.options[0] && context.options[0].testHooks;
 }

lib/rules/no-translation-key-interpolation.js

@@ -1,7 +1,5 @@
 'use strict';
 
-const isIdentifier = require('../utils/is-identifier');
-const isMemberExpression = require('../utils/is-member-expression');
 const { getImportIdentifier } = require('../utils/import');
 
 const DEFAULT_SERVICE_NAME = 'intl';
@@ -46,6 +44,7 @@ module.exports = {
       context.options &&
       context.options.length > 0 &&
       context.options[0].enforceStringLiteralKeys;
+    /** @type {string|undefined} */
     let importedTranslationMethodName;
 
     return {
@@ -59,7 +58,8 @@ module.exports = {
 
       CallExpression(node) {
         if (
-          (isT(node, importedTranslationMethodName) ||
+          ((importedTranslationMethodName &&
+            isT(node, importedTranslationMethodName)) ||
             isIntlT(node, serviceName) ||
             isThisIntlT(node, serviceName)) &&
           (node.arguments.length === 1 || node.arguments.length === 2)
@@ -80,37 +80,52 @@ module.exports = {
   },
 };
 
+/**
+ * @param {import('eslint').Rule.Node} node
+ * @param {string} importedTranslationMethodName
+ * @returns {boolean}
+ */
 function isT(node, importedTranslationMethodName) {
   // Example: import { t } from 'intl'; t(...);
   return (
     node.type === 'CallExpression' &&
-    isIdentifier(node.callee) &&
+    node.callee.type === 'Identifier' &&
     node.callee.name === importedTranslationMethodName
   );
 }
 
+/**
+ * @param {import('eslint').Rule.Node} node
+ * @param {string} serviceName
+ * @returns {boolean}
+ */
 function isIntlT(node, serviceName) {
   // Example: intl.t(...);
   return (
     node.type === 'CallExpression' &&
-    isMemberExpression(node.callee) &&
-    isIdentifier(node.callee.object) &&
+    node.callee.type === 'MemberExpression' &&
+    node.callee.object.type === 'Identifier' &&
     node.callee.object.name === serviceName &&
-    isIdentifier(node.callee.property) &&
+    node.callee.property.type === 'Identifier' &&
     node.callee.property.name === DEFAULT_METHOD_NAME
   );
 }
 
+/**
+ * @param {import('eslint').Rule.Node} node
+ * @param {string} serviceName
+ * @returns {boolean}
+ */
 function isThisIntlT(node, serviceName) {
   // Example: this.intl.t(...);
   return (
     node.type === 'CallExpression' &&
-    isMemberExpression(node.callee) &&
-    isMemberExpression(node.callee.object) &&
+    node.callee.type === 'MemberExpression' &&
+    node.callee.object.type === 'MemberExpression' &&
     node.callee.object.object.type === 'ThisExpression' &&
-    isIdentifier(node.callee.object.property) &&
+    node.callee.object.property.type === 'Identifier' &&
     node.callee.object.property.name === serviceName &&
-    isIdentifier(node.callee.property) &&
+    node.callee.property.type === 'Identifier' &&
     node.callee.property.name === DEFAULT_METHOD_NAME
   );
 }

lib/rules/require-await-function.js

@@ -1,12 +1,9 @@
 'use strict';
 
-const isIdentifier = require('../utils/is-identifier');
-const isMemberExpression = require('../utils/is-member-expression');
-
 /**
  * Checks if the given node is part of a call with the `await` keyword.
  *
- * @param {ASTNode} node - the node to check.
+ * @param {import('eslint').Rule.Node} node - the node to check.
  * @returns {boolean} `true` if the node is part of a call with the `await` keyword.
  */
 function isAwaitCall(node) {
@@ -16,7 +13,7 @@ function isAwaitCall(node) {
     return true;
   }
 
-  if (parent.type === 'CallExpression' || isMemberExpression(parent)) {
+  if (parent.type === 'CallExpression' || parent.type === 'MemberExpression') {
     // Check to see if the AwaitExpression is still another level above.
     return isAwaitCall(parent);
   }
@@ -27,7 +24,7 @@ function isAwaitCall(node) {
 /**
  * Checks if the given node is part of a call with the `return` keyword or direct arrow return.
  *
- * @param {ASTNode} node - the node to check.
+ * @param {import('eslint').Rule.Node} node - the node to check.
  * @returns {boolean} `true` if the node is part of a returned call
  */
 function isReturnCall(node) {
@@ -40,7 +37,7 @@ function isReturnCall(node) {
     return true;
   }
 
-  if (parent.type === 'CallExpression' || isMemberExpression(parent)) {
+  if (parent.type === 'CallExpression' || parent.type === 'MemberExpression') {
     return isReturnCall(parent);
   }
 
@@ -50,7 +47,7 @@ function isReturnCall(node) {
 /**
  * Checks if the given node is a nested call
  *
- * @param {ASTNode} node - the node to check.
+ * @param {import('eslint').Rule.Node} node - the node to check.
  * @returns {boolean} `true` if the node is nested within another function
  */
 function isNestedCall(node, isPromiseChain = false) {
@@ -64,7 +61,7 @@ function isNestedCall(node, isPromiseChain = false) {
     }
   }
 
-  if (isMemberExpression(parent)) {
+  if (parent.type === 'MemberExpression') {
     return isNestedCall(parent, true);
   }
 
@@ -102,10 +99,9 @@ module.exports = {
   create(context) {
     return {
       CallExpression(node) {
-        const callee = node.callee;
         if (
-          !isIdentifier(callee) ||
-          !context.options[0].functions.includes(callee.name)
+          node.callee.type !== 'Identifier' ||
+          !context.options[0].functions.includes(node.callee.name)
         ) {
           // Not one of the specified async functions.
           return;

lib/rules/use-call-count-test-assert.js

@@ -12,7 +12,7 @@ const STUB_PROPERTY_NAMES = [
   'called',
 ];
 
-/** @type {import('eslint').Rule.RuleModule} */
+/** @type {import('eslint').Rule.RuleModule & { ASSERT_PROPERTY_NAMES: string[], STUB_PROPERTY_NAMES: string[] }} */
 module.exports = {
   ASSERT_PROPERTY_NAMES,
   STUB_PROPERTY_NAMES,
@@ -39,28 +39,38 @@ module.exports = {
     return {
       CallExpression(node) {
         if (
-          !node.callee ||
-          !node.callee.object ||
+          node.callee.type !== 'MemberExpression' ||
+          node.callee.object.type !== 'Identifier' ||
           node.callee.object.name !== 'assert'
         ) {
           return;
         }
 
-        const assertPropertyName = node.callee.property
-          ? node.callee.property.name
-          : null;
-        if (!ASSERT_PROPERTY_NAMES.includes(assertPropertyName)) {
+        const assertPropertyName =
+          node.callee.type === 'MemberExpression' &&
+          node.callee.property.type === 'Identifier'
+            ? node.callee.property.name
+            : null;
+        if (
+          !assertPropertyName ||
+          !ASSERT_PROPERTY_NAMES.includes(assertPropertyName)
+        ) {
           return;
         }
 
         if (node.arguments.length === 0) {
           return;
         }
 
-        const stubPropertyName = node.arguments[0].property
-          ? node.arguments[0].property.name
-          : null;
-        if (!STUB_PROPERTY_NAMES.includes(stubPropertyName)) {
+        const stubPropertyName =
+          node.arguments[0].type === 'MemberExpression' &&
+          node.arguments[0].property.type === 'Identifier'
+            ? node.arguments[0].property.name
+            : null;
+        if (
+          !stubPropertyName ||
+          !STUB_PROPERTY_NAMES.includes(stubPropertyName)
+        ) {
           return;
         }
 
@@ -81,6 +91,13 @@ module.exports = {
             const text = sourceCode.getText(node);
 
             // Get `this.myStub` out of the `this.myStub.calledOnce` parameter.
+            if (
+              node.arguments[0].type !== 'MemberExpression' ||
+              !node.arguments[0].object.range ||
+              !node.range
+            ) {
+              return null;
+            }
             const stub = text.slice(
               node.arguments[0].object.range[0] - node.range[0],
               node.arguments[0].object.range[1] - node.range[0]
@@ -93,7 +110,7 @@ module.exports = {
 
             // Retrieve the optional message parameter.
             const optionalMessageParameter =
-              node.arguments.length === 2
+              node.arguments.length === 2 && node.arguments[1].range
                 ? text.slice(
                     node.arguments[1].range[0] - node.range[0],
                     node.arguments[1].range[1] - node.range[0]