Use eslint-tooling

.eslintignore

@@ -6,3 +6,4 @@ production_node_modules/*
 test/fixtures/*
 tmp/*
 jest.config.js
+/.eslintrc.js

.eslintrc.js

@@ -2,74 +2,8 @@ module.exports = {
   root: true,
   parser: '@typescript-eslint/parser',
   parserOptions: {
-    project: 'tsconfig.json',
+    project: ['./tsconfig.eslint.json'],
     tsconfigRootDir: __dirname,
-    ecmaVersion: 2018,
-    sourceType: 'module',
-    ecmaFeatures: {
-      modules: true,
-    },
-  },
-  env: {
-    es6: true,
-    node: true,
-  },
-  plugins: ['import', '@typescript-eslint'],
-  extends: [
-    'eslint:recommended',
-    'plugin:@typescript-eslint/eslint-recommended',
-    'plugin:@typescript-eslint/recommended',
-    'prettier',
-    'plugin:import/errors',
-    'plugin:import/warnings',
-    'plugin:import/typescript',
-  ],
-  rules: {
-    '@typescript-eslint/explicit-function-return-type': [
-      'warn',
-      {
-        allowExpressions: false,
-        allowTypedFunctionExpressions: true,
-        allowHigherOrderFunctions: true,
-      },
-    ],
-    '@typescript-eslint/explicit-member-accessibility': [
-      'warn',
-      {
-        accessibility: 'no-public',
-        overrides: {
-          accessors: 'explicit',
-          constructors: 'no-public',
-          methods: 'explicit',
-          properties: 'explicit',
-          parameterProperties: 'off',
-        },
-      },
-    ],
-    '@typescript-eslint/no-non-null-assertion': 'off',
-    '@typescript-eslint/no-parameter-properties': [
-      'warn',
-      {
-        allows: [
-          'private',
-          'protected',
-          'public',
-          'private readonly',
-          'protected readonly',
-          'public readonly',
-        ],
-      },
-    ],
-    '@typescript-eslint/no-unused-vars': 'off',
-    '@typescript-eslint/no-use-before-define': [
-      'error',
-      {
-        functions: false,
-        typedefs: false,
-      },
-    ],
-    'import/no-unresolved': 'off',
-    'no-extra-semi': 'off',
-    '@typescript-eslint/no-extra-semi': ['off'],
   },
+  extends: ['@exercism/eslint-config-tooling'],
 }

.vscode/settings.json

@@ -0,0 +1,7 @@
+{
+  "cSpell.words": [
+    "REPRESENTER",
+    "TSESTree",
+    "quasis"
+  ]
+}

package.json

@@ -26,6 +26,7 @@
     "@babel/core": "^7.13.15",
     "@babel/preset-env": "^7.13.15",
     "@babel/preset-typescript": "^7.13.0",
+    "@exercism/eslint-config-tooling": "^0.1.0",
     "@tsconfig/recommended": "^1.0.1",
     "@types/jest": "^26.0.22",
     "@types/node": "^14.14.41",

src/AstParser.ts

@@ -4,7 +4,7 @@ import type { TSESTree } from '@typescript-eslint/typescript-estree'
 
 import { NoSourceError } from './errors/NoSourceError'
 import { ParserError } from './errors/ParserError'
-import { Input } from './input/Input'
+import type { Input } from './input/Input'
 import { getProcessLogger } from './utils/logger'
 
 type Program = TSESTree.Program
@@ -82,6 +82,7 @@ export class AstParser {
    * does not hold locational information (where differences are caused by
    * whitespace differences) or commentary.
    */
+  // eslint-disable-next-line @typescript-eslint/naming-convention
   public static REPRESENTER: AstParser = new AstParser({
     comment: false,
     loc: false,
@@ -93,6 +94,7 @@ export class AstParser {
    * hold locational information (in order to be able to extract tokens), but
    * does not hold any commentary.
    */
+  // eslint-disable-next-line @typescript-eslint/naming-convention
   public static ANALYZER: AstParser = new AstParser({
     comment: false,
     loc: true,
@@ -119,7 +121,9 @@ export class AstParser {
     const logger = getProcessLogger()
 
     logger.log(`=> inputs: ${sources.length}`)
-    sources.forEach((source): void => logger.log(`\n${source}\n`))
+    sources.forEach((source): void => {
+      logger.log(`\n${source}\n`)
+    })
 
     if (sources.length === 0) {
       throw new NoSourceError()
@@ -130,8 +134,12 @@ export class AstParser {
         (source): ParsedSource =>
           new ParsedSource(parseToTree(source, this.options), source)
       )
-    } catch (error) {
-      throw new ParserError(error)
+    } catch (error: unknown) {
+      if (error instanceof Error) {
+        throw new ParserError(error)
+      } else {
+        throw error
+      }
     }
   }
 }

src/AstTraverser.ts

@@ -1,5 +1,5 @@
 import { visitorKeys } from '@typescript-eslint/visitor-keys'
-import { TSESTree } from '@typescript-eslint/typescript-estree'
+import type { TSESTree } from '@typescript-eslint/typescript-estree'
 
 type Node = TSESTree.Node
 
@@ -125,5 +125,5 @@ export class AstTraverser {
 }
 
 export function traverse(root: Node, options: TraverseOptions): void {
-  return new AstTraverser(options).traverse(root)
+  return void new AstTraverser(options).traverse(root)
 }

src/errors/NoSourceAnnotations.ts

@@ -1,4 +1,4 @@
-import { TSESTree } from '@typescript-eslint/typescript-estree'
+import type { TSESTree } from '@typescript-eslint/typescript-estree'
 import { AnalysisError } from './AnalysisError'
 import { WRONG_ANALYZER_FOR_METHOD } from './codes'
 

src/errors/ParserError.ts

@@ -6,9 +6,9 @@ export class ParserError extends AnalysisError {
 
   constructor(
     public readonly original: Error & {
-      lineNumber: number
-      column: number
-      index: number
+      lineNumber?: number
+      column?: number
+      index?: number
     },
     public readonly source?: string
   ) {

src/errors/handler.ts

@@ -20,7 +20,7 @@ export function reportException<
   }
 
   const errorMessage = `
-An uncaughtException occurred (code: ${err.code || GENERIC_FAILURE}).
+An uncaughtException occurred (code: ${err.code ?? GENERIC_FAILURE}).
 
 Error Data:
 ${JSON.stringify(err)}
@@ -34,7 +34,7 @@ ${err.stack ? err.stack : '<no stack>'}
 
   if (typeof process !== 'undefined') {
     // Write error to stderr as well
-    process.stderr && process.stderr.write(errorMessage)
+    process.stderr?.write(errorMessage)
   }
 
   if (process.exit) {

src/extracts/extract_exports.ts

@@ -1,5 +1,5 @@
-import { AST_NODE_TYPES, TSESTree } from '@typescript-eslint/typescript-estree'
-import { Expression } from 'typescript'
+import type { TSESTree } from '@typescript-eslint/typescript-estree'
+import { AST_NODE_TYPES } from '@typescript-eslint/typescript-estree'
 import { traverse } from '../AstTraverser'
 import { guardIdentifier } from '../guards/is_identifier'
 import { guardLiteral } from '../guards/is_literal'
@@ -258,7 +258,7 @@ export function extractExports(root: Node): ExtractedExport[] {
               exports.push(
                 new ExtractedExport(
                   node,
-                  declaration.id?.name || ANONYMOUS,
+                  declaration.id?.name ?? ANONYMOUS,
                   'default',
                   'value',
                   'class'
@@ -273,7 +273,7 @@ export function extractExports(root: Node): ExtractedExport[] {
               exports.push(
                 new ExtractedExport(
                   node,
-                  declaration.id?.name || ANONYMOUS,
+                  declaration.id?.name ?? ANONYMOUS,
                   'default',
                   'value',
                   'function'

src/extracts/extract_functions.ts

@@ -1,4 +1,5 @@
-import { AST_NODE_TYPES, TSESTree } from '@typescript-eslint/typescript-estree'
+import type { TSESTree } from '@typescript-eslint/typescript-estree'
+import { AST_NODE_TYPES } from '@typescript-eslint/typescript-estree'
 import { traverse } from '../AstTraverser'
 import { guardIdentifier } from '../guards'
 import { ExtractedVariable } from './extract_variables'

src/extracts/extract_source.ts

@@ -1,4 +1,4 @@
-import { TSESTree } from '@typescript-eslint/typescript-estree'
+import type { TSESTree } from '@typescript-eslint/typescript-estree'
 import { NoSourceAnnotations } from '../errors'
 
 type NodeWithLocation = TSESTree.Node & {

src/extracts/extract_tests.ts

@@ -1,10 +1,11 @@
-import { AST_NODE_TYPES, TSESTree } from '@typescript-eslint/typescript-estree'
+import type { TSESTree } from '@typescript-eslint/typescript-estree'
+import { AST_NODE_TYPES } from '@typescript-eslint/typescript-estree'
 import { traverse } from '../AstTraverser'
-import {
+import type {
   CallExpression,
-  guardCallExpression,
   SpecificFunctionCall,
 } from '../guards/is_call_expression'
+import { guardCallExpression } from '../guards/is_call_expression'
 import { guardIdentifier } from '../guards/is_identifier'
 import { guardLiteral } from '../guards/is_literal'
 import { guardMemberExpression } from '../guards/is_member_expression'

src/extracts/extract_variables.ts

@@ -1,11 +1,13 @@
-import { AST_NODE_TYPES, TSESTree } from '@typescript-eslint/typescript-estree'
+import type { TSESTree } from '@typescript-eslint/typescript-estree'
+import { AST_NODE_TYPES } from '@typescript-eslint/typescript-estree'
 import { findAll } from '../queries/find_all'
 import { guardIdentifier } from '../guards/is_identifier'
 
 type Node = TSESTree.Node
 type BindingName = TSESTree.BindingName
 type Expression = TSESTree.Expression
 type VariableDeclaration = TSESTree.VariableDeclaration
+type VariableDeclarator = TSESTree.VariableDeclarator
 
 export class ExtractedVariable {
   public readonly name: string | null
@@ -31,37 +33,51 @@ export function extractVariables(root: Node): ExtractedVariable[] {
       node.type === AST_NODE_TYPES.VariableDeclaration
   )
 
-  return declarations.flatMap((node) => {
-    const { declarations, kind } = node
+  return declarations.flatMap(
+    (node: VariableDeclaration): ExtractedVariable[] => {
+      const { declarations, kind } = node
 
-    return declarations.flatMap((declarator) => {
-      switch (declarator.id.type) {
-        // const identifier = ...
-        // const identifier, identifier = ...
-        case AST_NODE_TYPES.Identifier: {
-          return [
-            new ExtractedVariable(node, declarator.id, kind, declarator.init),
-          ]
-        }
+      return declarations.flatMap(
+        (declarator: VariableDeclarator): ExtractedVariable[] => {
+          switch (declarator.id.type) {
+            // const identifier = ...
+            // const identifier, identifier = ...
+            case AST_NODE_TYPES.Identifier: {
+              return [
+                new ExtractedVariable(
+                  node,
+                  declarator.id,
+                  kind,
+                  declarator.init
+                ),
+              ]
+            }
 
-        // const [identifier, identifier2] = ...
-        case AST_NODE_TYPES.ArrayPattern: {
-          return declarator.id.elements
-            .map((element) => {
-              if (element === null || !guardIdentifier(element)) {
-                return null
-              }
+            // const [identifier, identifier2] = ...
+            case AST_NODE_TYPES.ArrayPattern: {
+              return declarator.id.elements
+                .map((element) => {
+                  if (element === null || !guardIdentifier(element)) {
+                    return null
+                  }
 
-              return new ExtractedVariable(node, element, kind, declarator.init)
-            })
-            .filter(Boolean) as ExtractedVariable[]
-        }
+                  return new ExtractedVariable(
+                    node,
+                    element,
+                    kind,
+                    declarator.init
+                  )
+                })
+                .filter(Boolean) as ExtractedVariable[]
+            }
 
-        //
-        default: {
-          return []
+            //
+            default: {
+              return []
+            }
+          }
         }
-      }
-    })
-  })
+      )
+    }
+  )
 }

src/guards/is_assignment_pattern.ts

@@ -1,4 +1,5 @@
-import { AST_NODE_TYPES, TSESTree } from '@typescript-eslint/typescript-estree'
+import type { TSESTree } from '@typescript-eslint/typescript-estree'
+import { AST_NODE_TYPES } from '@typescript-eslint/typescript-estree'
 import { guardIdentifier } from './is_identifier'
 import { guardLiteral } from './is_literal'
 

src/guards/is_binary_expression.ts

@@ -1,4 +1,5 @@
-import { AST_NODE_TYPES, TSESTree } from '@typescript-eslint/typescript-estree'
+import type { TSESTree } from '@typescript-eslint/typescript-estree'
+import { AST_NODE_TYPES } from '@typescript-eslint/typescript-estree'
 
 type Node = TSESTree.Node
 export type BinaryExpression = TSESTree.BinaryExpression

src/guards/is_call_expression.ts

@@ -1,10 +1,9 @@
-import { AST_NODE_TYPES, TSESTree } from '@typescript-eslint/typescript-estree'
-import {
-  guardMemberExpression,
-  SpecificObject,
-  SpecificProperty,
-} from './is_member_expression'
-import { guardIdentifier, Identifier } from './is_identifier'
+import type { TSESTree } from '@typescript-eslint/typescript-estree'
+import { AST_NODE_TYPES } from '@typescript-eslint/typescript-estree'
+import type { SpecificObject, SpecificProperty } from './is_member_expression'
+import { guardMemberExpression } from './is_member_expression'
+import type { Identifier } from './is_identifier'
+import { guardIdentifier } from './is_identifier'
 
 type Node = TSESTree.Node
 export type CallExpression = TSESTree.CallExpression