Lint rule to detect unminified errors

Adds a lint rule that detects when an Error constructor is used without
a corresponding production error code.

We already have this for `invariant`, but not for regular errors, i.e.
`throw new Error(msg)`. There's also nothing that enforces the use of
`invariant` besides convention.

There are some packages where we don't care to minify errors. These are
packages that run in environments where bundle size is not a concern,
like react-pg. I added an override in the ESLint config to ignore these.

Author: acdlite

.eslintrc.js

@@ -123,6 +123,38 @@ module.exports = {
   },
 
   overrides: [
+    {
+      // By default, anything error message that appears the packages directory
+      // must have a corresponding error code. The exceptions are defined
+      // in the next override entry.
+      files: ['packages/react-dom/**/*.js'],
+      rules: {
+        'react-internal/prod-error-codes': ERROR,
+      },
+    },
+    {
+      // These are files where it's OK to have unminified error messages. These
+      // are environments where bundle size isn't a concern, like tests
+      // or Node.
+      files: [
+        'packages/react-dom/src/test-utils/**/*.js',
+        'packages/react-devtools-shared/**/*.js',
+        'packages/react-noop-renderer/**/*.js',
+        'packages/react-pg/**/*.js',
+        'packages/react-fs/**/*.js',
+        'packages/react-refresh/**/*.js',
+        'packages/react-server-dom-webpack/**/*.js',
+        'packages/react-test-renderer/**/*.js',
+        '**/__tests__/*.js',
+
+        // TODO: Should React Native messages be minified in prod? We're not
+        // consistent about it.
+        'packages/react-native-renderer/**/*.js',
+      ],
+      rules: {
+        'react-internal/prod-error-codes': OFF,
+      },
+    },
     {
       // We apply these settings to files that we ship through npm.
       // They must be ES5.
@@ -185,7 +217,7 @@ module.exports = {
     {
       files: [
         'scripts/eslint-rules/*.js',
-        'packages/eslint-plugin-react-hooks/src/*.js'
+        'packages/eslint-plugin-react-hooks/src/*.js',
       ],
       plugins: ['eslint-plugin'],
       rules: {

packages/react-dom/npm/index.js

@@ -16,6 +16,7 @@ function checkDCE() {
     // Don't change the message. React DevTools relies on it. Also make sure
     // this message doesn't occur elsewhere in this function, or it will cause
     // a false positive.
+    // eslint-disable-next-line react-internal/prod-error-codes
     throw new Error('^_^');
   }
   try {

packages/react-dom/npm/profiling.js

@@ -16,6 +16,7 @@ function checkDCE() {
     // Don't change the message. React DevTools relies on it. Also make sure
     // this message doesn't occur elsewhere in this function, or it will cause
     // a false positive.
+    // eslint-disable-next-line react-internal/prod-error-codes
     throw new Error('^_^');
   }
   try {

packages/react-dom/npm/testing.js

@@ -16,6 +16,7 @@ function checkDCE() {
     // Don't change the message. React DevTools relies on it. Also make sure
     // this message doesn't occur elsewhere in this function, or it will cause
     // a false positive.
+    // eslint-disable-next-line react-internal/prod-error-codes
     throw new Error('^_^');
   }
   try {

scripts/eslint-rules/__tests__/prod-error-codes-test.internal.js

@@ -0,0 +1,77 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @emails react-core
+ */
+
+'use strict';
+
+const rule = require('../prod-error-codes');
+const {RuleTester} = require('eslint');
+const ruleTester = new RuleTester({
+  parserOptions: {
+    ecmaVersion: 2017,
+  },
+});
+
+ruleTester.run('eslint-rules/prod-error-codes', rule, {
+  valid: [
+    'arbitraryFunction(a, b)',
+    'Error(`Expected ${foo} target to be an array; got ${bar}`)',
+    "Error('Expected ' + foo + ' target to be an array; got ' + bar)",
+    'Error(`Expected ${foo} target to ` + `be an array; got ${bar}`)',
+  ],
+  invalid: [
+    {
+      code: "Error('Not in error map')",
+      errors: [
+        {
+          message:
+            'Error message does not have a corresponding production error ' +
+            'code. Add the following message to codes.json so it can be stripped from ' +
+            'the production builds:\n\n' +
+            'Not in error map',
+        },
+      ],
+    },
+    {
+      code: "Error('Not in ' + 'error map')",
+      errors: [
+        {
+          message:
+            'Error message does not have a corresponding production error ' +
+            'code. Add the following message to codes.json so it can be stripped from ' +
+            'the production builds:\n\n' +
+            'Not in error map',
+        },
+      ],
+    },
+    {
+      code: 'Error(`Not in ` + `error map`)',
+      errors: [
+        {
+          message:
+            'Error message does not have a corresponding production error ' +
+            'code. Add the following message to codes.json so it can be stripped from ' +
+            'the production builds:\n\n' +
+            'Not in error map',
+        },
+      ],
+    },
+    {
+      code: "Error(`Not in ${'error'} map`)",
+      errors: [
+        {
+          message:
+            'Error message does not have a corresponding production error ' +
+            'code. Add the following message to codes.json so it can be stripped from ' +
+            'the production builds:\n\n' +
+            'Not in %s map',
+        },
+      ],
+    },
+  ],
+});

scripts/eslint-rules/index.js

@@ -6,6 +6,7 @@ module.exports = {
     'no-to-warn-dev-within-to-throw': require('./no-to-warn-dev-within-to-throw'),
     'warning-args': require('./warning-args'),
     'invariant-args': require('./invariant-args'),
+    'prod-error-codes': require('./prod-error-codes'),
     'no-production-logging': require('./no-production-logging'),
     'no-cross-fork-imports': require('./no-cross-fork-imports'),
     'no-cross-fork-types': require('./no-cross-fork-types'),

scripts/eslint-rules/prod-error-codes.js

@@ -0,0 +1,79 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @emails react-core
+ */
+
+'use strict';
+
+const fs = require('fs');
+const path = require('path');
+const errorMap = JSON.parse(
+  fs.readFileSync(path.resolve(__dirname, '../error-codes/codes.json'))
+);
+const errorMessages = new Set();
+Object.keys(errorMap).forEach(key => errorMessages.add(errorMap[key]));
+
+function nodeToErrorTemplate(node) {
+  if (node.type === 'Literal' && typeof node.value === 'string') {
+    return node.value;
+  } else if (node.type === 'BinaryExpression' && node.operator === '+') {
+    const l = nodeToErrorTemplate(node.left);
+    const r = nodeToErrorTemplate(node.right);
+    return l + r;
+  } else if (node.type === 'TemplateLiteral') {
+    let elements = [];
+    for (let i = 0; i < node.quasis.length; i++) {
+      const elementNode = node.quasis[i];
+      if (elementNode.type !== 'TemplateElement') {
+        throw new Error('Unsupported type ' + node.type);
+      }
+      elements.push(elementNode.value.raw);
+    }
+    return elements.join('%s');
+  } else {
+    return '%s';
+  }
+}
+
+module.exports = {
+  meta: {
+    schema: [],
+  },
+  create(context) {
+    function ErrorCallExpression(node) {
+      const errorMessageNode = node.arguments[0];
+      if (errorMessageNode === undefined) {
+        return;
+      }
+      const errorMessage = nodeToErrorTemplate(errorMessageNode);
+      if (errorMessages.has(errorMessage)) {
+        return;
+      }
+      context.report({
+        node,
+        message:
+          'Error message does not have a corresponding production error code. Add ' +
+          'the following message to codes.json so it can be stripped ' +
+          'from the production builds:\n\n' +
+          errorMessage,
+      });
+    }
+
+    return {
+      NewExpression(node) {
+        if (node.callee.type === 'Identifier' && node.callee.name === 'Error') {
+          ErrorCallExpression(node);
+        }
+      },
+      CallExpression(node) {
+        if (node.callee.type === 'Identifier' && node.callee.name === 'Error') {
+          ErrorCallExpression(node);
+        }
+      },
+    };
+  },
+};