Inline Istanbul ignore reason rule

With updated and stricter tests, outdated plugin no longer required.

index.js

@@ -9,7 +9,6 @@ import tsParser from '@typescript-eslint/parser';
 import eslintConfigPrettier from 'eslint-config-prettier';
 import cypress from 'eslint-plugin-cypress';
 import importPlugin from 'eslint-plugin-import';
-import istanbul from 'eslint-plugin-istanbul';
 import noOnlyTestsPlugin from 'eslint-plugin-no-only-tests';
 import prettier from 'eslint-plugin-prettier';
 import sortDestructureKeysPlugin from 'eslint-plugin-sort-destructure-keys';
@@ -18,6 +17,8 @@ import tsSortKeysPlugin from 'eslint-plugin-typescript-sort-keys';
 import vitest from 'eslint-plugin-vitest';
 import globals from 'globals';
 
+import internalRules from './internal-rules/index.js';
+
 // mimic CommonJS variables -- not needed if using CommonJS
 const __filename = fileURLToPath(import.meta.url);
 const __dirname = path.dirname(__filename);
@@ -48,7 +49,7 @@ export default [
       '@jambit/typed-redux-saga': typedReduxSagaPlugin,
       '@typescript-eslint': tsPlugin,
       import: importPlugin,
-      istanbul,
+      'internal-rules': internalRules,
       'no-only-tests': noOnlyTestsPlugin,
       prettier,
       'sort-destructure-keys': sortDestructureKeysPlugin,
@@ -137,8 +138,7 @@ export default [
         },
       ],
       'import/unambiguous': 'off',
-      'istanbul/no-ignore-file': 'error',
-      'istanbul/prefer-ignore-reason': 'error',
+      'internal-rules/require-coverage-ignore-reason': 'error',
       'max-depth': 'error',
       'max-param': 'off',
       'max-params': 'off',

internal-rules/index.js

@@ -0,0 +1,7 @@
+import { requireCoverageIgnoreReason } from './require-coverage-ignore-reason.js';
+
+export default {
+  rules: {
+    'require-coverage-ignore-reason': requireCoverageIgnoreReason,
+  },
+};

internal-rules/require-coverage-ignore-reason.js

@@ -0,0 +1,27 @@
+'use strict';
+// Extracted from: https://github.com/graphql/graphql-js/pull/3388 related to:
+// https://github.com/istanbuljs/eslint-plugin-istanbul/pull/17
+// Fixed reason length check and converted to ESM.
+
+export function requireCoverageIgnoreReason(context) {
+  const istanbulRegExp = /^\s*istanbul\s+ignore\s+(if|else|next|file)\s+/;
+  return {
+    Program() {
+      const sourceCode = context.getSourceCode();
+
+      for (const node of sourceCode.getAllComments()) {
+        const comment = node.value;
+
+        if (comment.match(istanbulRegExp)) {
+          const reason = comment.replace(istanbulRegExp, '');
+          if (reason.length === 0) {
+            context.report({
+              message: 'Add a reason why code coverage should be ignored',
+              node,
+            });
+          }
+        }
+      }
+    },
+  };
+}

package.json

@@ -74,7 +74,6 @@
     "eslint-plugin-cypress": "^2.14.0",
     "eslint-import-resolver-typescript": "^3.6.0",
     "eslint-plugin-import": "^2.28.1",
-    "eslint-plugin-istanbul": "0.1.2",
     "eslint-plugin-no-only-tests": "^3.1.0",
     "eslint-plugin-prettier": "5.0.0",
     "eslint-plugin-react": "7.33.2",

test/cases/nice-javascript.js

@@ -10,5 +10,6 @@ export const sha256 = async (/** @type {string} */ message) => {
   for (let i = 0; i < len; i += 1) {
     binary += String.fromCharCode(bytes[i]);
   }
+  /* istanbul ignore next because we have some very good reason to */
   return globalThis.btoa(binary);
 };

test/cases/ugly-javascript.js

@@ -7,6 +7,7 @@ var something = {
     return 'hello' + world
   },
   world(hai = 2) {
+    /* istanbul ignore next */
     return hai;
   }
 };

test/test.js

@@ -28,13 +28,24 @@ test('Fails on broken files', async t => {
   const expectedErrors = [
     'prettier/prettier',
     '@typescript-eslint/no-unused-vars',
+    'internal-rules/require-coverage-ignore-reason',
   ];
 
   const expectedErrorsFound = errorsAsRuleIds.filter(
     error => expectedErrors.indexOf(error) !== -1,
   );
 
+  // All expected error types are found:
   t.is(expectedErrorsFound.length, expectedErrors.length);
+
+  // All found errors are of expected types:
+  const unexpectedErrorsFound = errorsAsRuleIds.filter(
+    error => expectedErrors.indexOf(error) === -1,
+  );
+  t.is(unexpectedErrorsFound.length, 0);
+
+  // Total number of seen errors:
+  t.is(errors.length, 6);
 });
 
 test('Success on nice files', async t => {