Make ESLint rules stricter

.eslintrc.js

@@ -1,6 +1,9 @@
 /** @type{import("eslint").Linter.Config} */
 module.exports = {
-  extends: ["@kachkaev/eslint-config-base"],
+  extends: [
+    "@kachkaev/eslint-config-base",
+    "@kachkaev/eslint-config-base/extra-type-checking",
+  ],
   reportUnusedDisableDirectives: true,
   rules: {
     /* eslint-disable @typescript-eslint/naming-convention */

.github/workflows/ci.yml

@@ -29,7 +29,7 @@ jobs:
       - name: Run build
         run: yarn build
 
-  lint:
+  linting:
     name: Linting
     runs-on: ubuntu-latest
 
@@ -66,23 +66,22 @@ jobs:
         if: ${{ success() || failure() }}
         run: yarn lint:yarn-dedupe
 
-  unit-tests:
-    name: Unit tests
+  tests:
+    name: Tests
     runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: false
       matrix:
-        os: [macos-12, ubuntu-22.04, windows-2022]
+        os: [macos-12, windows-2022, ubuntu-22.04]
         node: [14, 16, 18, 19]
         exclude:
-          - os: macos-12
-            node: 14
-          - os: macos-12
-            node: 19
-          - os: windows-2022
-            node: 14
-          - os: windows-2022
-            node: 19
+          - os: ubuntu-22.04
+            node: 18
+        include:
+          - os: ubuntu-22.04
+            node: 18
+            extra: coverage
+          - os: ubuntu-22.04
 
     steps:
       - name: Check out repository
@@ -100,10 +99,10 @@ jobs:
       - name: Run unit tests
         run: yarn test
         env:
-          TEST_COVERAGE: ${{ matrix.os == 'ubuntu-22.04' && matrix.node == 18 }}
+          COVERAGE: ${{ matrix.extra == 'coverage' }}
 
       - name: Report code coverage to codecov.io
         uses: codecov/codecov-action@v3
-        if: matrix.os == 'ubuntu-22.04' && matrix.node == 18
+        if: matrix.extra == 'coverage'
         with:
           files: coverage/lcov.info

.npmignore

@@ -1,5 +1,5 @@
 *
-!dist/**/*
+!dist/**
 dist/**/*.test.*
 !package.json
 !README.md

jest.config.mjs

@@ -1,7 +1,7 @@
 /* eslint-disable import/no-anonymous-default-export */
 /** @type {import("jest").Config} */
 export default {
-  collectCoverage: !!process.env.TEST_COVERAGE,
+  collectCoverage: process.env.COVERAGE === "true",
   collectCoverageFrom: ["dist/**/*.js", "!dist/**/*.test.js"],
   testRegex: ".test.js$",
 };

package.json

@@ -16,12 +16,12 @@
   "scripts": {
     "build": "tsc",
     "clean": "rimraf cache coverage dist",
-    "fix": "npm-run-all --continue-on-error fix:*",
+    "fix": "npm-run-all --continue-on-error \"fix:*\"",
     "fix:eslint": "eslint --fix .",
     "fix:markdownlint": "markdownlint --fix .",
     "fix:prettier": "prettier --write .",
     "fix:yarn-dedupe": "yarn dedupe",
-    "lint": "npm-run-all --continue-on-error lint:*",
+    "lint": "npm-run-all --continue-on-error \"lint:*\"",
     "lint:markdownlint": "markdownlint .",
     "lint:prettier": "prettier --check .",
     "lint:tsc": "tsc --noEmit",

src/cache.test.ts

@@ -4,7 +4,7 @@ import prettier from "prettier";
 import rimraf from "rimraf";
 import sleep from "sleep-promise";
 
-import * as util from "./util";
+import * as helpers from "./helpers";
 
 const fixturesDir = path.resolve(__dirname, "../fixtures");
 const cacheDir = path.resolve(__dirname, "../cache");
@@ -18,7 +18,7 @@ test(`correctly deals with cache`, async () => {
   process.env.PRETTIER_PLUGIN_ELM_CACHE_GC_INTERVAL = `${cacheGcInterval}`;
 
   const spyForFormatTextWithElmFormat = jest.spyOn(
-    util,
+    helpers,
     "formatTextWithElmFormat",
   );
 

src/cache.ts

@@ -86,7 +86,10 @@ export const getCachedValue = <Args extends any[], Result>(
 
   // load value or error from cache
   try {
-    record = JSON.parse(fs.readFileSync(recordFilePath, "utf8"));
+    record = JSON.parse(fs.readFileSync(recordFilePath, "utf8")) as {
+      value: Result;
+      error?: undefined;
+    };
     recordIsFromCache = true;
   } catch {
     // a failure to load from cache implies calling fn
@@ -122,11 +125,11 @@ export const getCachedValue = <Args extends any[], Result>(
 
   if ("error" in record) {
     // eslint-disable-next-line unicorn/error-message
-    const errorToThrow = new Error();
+    const errorToThrow = new Error() as Error & Record<string, unknown>;
     for (const errorProperty in record.error) {
       /* istanbul ignore else */
       if (Object.prototype.hasOwnProperty.call(record.error, errorProperty)) {
-        (errorToThrow as any)[errorProperty] = record.error.property;
+        errorToThrow[errorProperty] = record.error.property;
       }
     }
     throw errorToThrow;

src/util.ts → src/helpers.ts

@@ -1,6 +1,7 @@
 import execa from "execa";
 
 let cachedElmFormatVersion: string;
+
 export const getElmFormatVersion = () => {
   if (!cachedElmFormatVersion) {
     // a cleaner way of getting elm-format version

src/index.ts

@@ -1,5 +1,8 @@
+import type { Parser, Printer } from "prettier";
+
 import { parse } from "./parser";
 import { print } from "./printer";
+import type { ElmNode } from "./types";
 
 export const defaultOptions = {};
 
@@ -16,21 +19,21 @@ export const languages = [
   },
 ];
 
-export const parsers = {
+export const parsers: Record<string, Parser<ElmNode>> = {
   elm: {
     parse,
     astFormat: "elm-format",
     // there's only a single node
-    locStart(node: any) {
+    locStart(node) {
       return node.start;
     },
-    locEnd(node: any) {
+    locEnd(node) {
       return node.end;
     },
   },
 };
 
-export const printers = {
+export const printers: Record<string, Printer<ElmNode>> = {
   // eslint-disable-next-line @typescript-eslint/naming-convention
   "elm-format": {
     print,

src/parser.ts

@@ -1,10 +1,11 @@
-import { Parser, ParserOptions } from "prettier";
+import type { Parser, ParserOptions } from "prettier";
 
 import { getCachedValue } from "./cache";
-import { formatTextWithElmFormat, getElmFormatVersion } from "./util";
+import { formatTextWithElmFormat, getElmFormatVersion } from "./helpers";
+import type { ElmNode } from "./types";
 
 // eslint-disable-next-line @typescript-eslint/no-var-requires
-const pkg = require("../package.json");
+const pkg = require("../package.json") as { version: string };
 
 /*
  * Simply passing text to elm-format is not enough because of two problems:
@@ -34,8 +35,8 @@ const autogeneratedModuleDefinitionRegExp =
 export const parse = (
   text: string,
   parsers: { [parserName: string]: Parser },
-  opts: ParserOptions & { parentParser?: string },
-) => {
+  options: ParserOptions,
+): ElmNode => {
   // patch 1 step 1
   const textToSend = `${text}${dummyComment}`;
 
@@ -54,7 +55,7 @@ export const parse = (
 
   // patch 2
   if (
-    opts.parentParser === "markdown" &&
+    options.parentParser === "markdown" &&
     autogeneratedModuleDefinitionRegExp.test(formattedText) &&
     !autogeneratedModuleDefinitionRegExp.test(text)
   ) {

src/printer.ts

@@ -1,6 +1,8 @@
-import { AstPath } from "prettier";
+import type { AstPath, Doc } from "prettier";
 
-export const print = (path: AstPath) => {
+import type { ElmNode } from "./types";
+
+export const print = (path: AstPath<ElmNode>): Doc => {
   const node = path.getValue();
 
   switch (node.type) {

src/types.ts

@@ -0,0 +1,7 @@
+export interface ElmNode {
+  type: "elm-format";
+  body: string;
+  source: string;
+  start: number;
+  end: number;
+}

tsconfig.json

@@ -3,6 +3,7 @@
     "esModuleInterop": true,
     "inlineSourceMap": true,
     "lib": ["ES2019"],
+    "isolatedModules": true,
     "module": "commonjs",
     "checkJs": true,
     "outDir": "dist",