Move error-subclass-name lint rule to GitHub

Summary: Ports an internal ESLint rule used at Facebook, `error-subclass-name`, to cover the React Native codebase. This rule enforces that error classes ( = those with PascalCase names ending with `Error`) only extend other error classes, and that regular functions don't have names that could be mistaken for those of error classes.

Reviewed By: rubennorte

Differential Revision: D17829298

fbshipit-source-id: 834e457343034a0897ab394b6a2d941789953d2e

.eslintrc

@@ -11,7 +11,8 @@
         "Libraries/**/*.js",
       ],
       rules: {
-        '@react-native-community/no-haste-imports': 2
+        '@react-native-community/no-haste-imports': 2,
+        '@react-native-community/error-subclass-name': 2,
       }
     },
     {

package.json

@@ -119,7 +119,7 @@
   "devDependencies": {
     "@babel/core": "^7.0.0",
     "@babel/generator": "^7.0.0",
-    "@react-native-community/eslint-plugin": "1.0.0",
+    "@react-native-community/eslint-plugin": "file:packages/eslint-plugin-react-native-community",
     "@reactions/component": "^2.0.2",
     "async": "^2.4.0",
     "babel-eslint": "10.0.1",

packages/eslint-plugin-react-native-community/BUCK

@@ -0,0 +1,23 @@
+load("@fbsource//tools/build_defs/third_party:yarn_defs.bzl", "yarn_workspace")
+
+yarn_workspace(
+    name = "yarn-workspace",
+    srcs = glob(
+        ["**/*.js"],
+        exclude = [
+            "**/__fixtures__/**",
+            "**/__flowtests__/**",
+            "**/__mocks__/**",
+            "**/__server_snapshot_tests__/**",
+            "**/__tests__/**",
+            "**/node_modules/**",
+            "**/node_modules/.bin/**",
+            "**/.*",
+            "**/.*/**",
+            "**/.*/.*",
+            "**/*.xcodeproj/**",
+            "**/*.xcworkspace/**",
+        ],
+    ),
+    visibility = ["PUBLIC"],
+)

packages/eslint-plugin-react-native-community/README.md

@@ -19,3 +19,15 @@ Add to your eslint config (`.eslintrc`, or `eslintConfig` field in `package.json
     "plugins": ["@react-native-community"]
 }
 ```
+
+## Rules
+
+### `error-subclass-name`
+
+**NOTE:** This rule is primarily used for developing React Native itself and is not generally applicable to other projects.
+
+Enforces that error classes ( = classes with PascalCase names ending with `Error`) only extend other error classes, and that regular functions don't have names that could be mistaken for those of error classes.
+
+### `no-haste-imports`
+
+Disallows Haste module names in `import` statements and `require()` calls.

packages/eslint-plugin-react-native-community/__tests__/error-subclass-name-test.js

@@ -0,0 +1,100 @@
+/**
+ * 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 oncall+react_native
+ * @format
+ */
+
+'use strict';
+
+const ESLintTester = require('./eslint-tester.js');
+
+const rule = require('../error-subclass-name.js');
+
+const eslintTester = new ESLintTester();
+
+const INVALID_SUPERCLASS_MESSAGE =
+  "'SomethingEndingWithError' must extend an error class (like 'Error') because its name is in PascalCase and ends with 'Error'.";
+const INVALID_OWN_NAME_MESSAGE =
+  "'Foo' may not be the name of an error class. It should be in PascalCase and end with 'Error'.";
+const MISSING_OWN_NAME_MESSAGE =
+  "An error class should have a PascalCase name ending with 'Error'.";
+const INVALID_FUNCTION_NAME_MESSAGE =
+  "'SomethingEndingWithError' is a reserved name. PascalCase names ending with 'Error' are reserved for error classes and may not be used for regular functions. Either rename this function or convert it to a class that extends 'Error'.";
+
+eslintTester.run('../error-subclass-name', rule, {
+  valid: [
+    'class FooError extends Error {}',
+    '(class FooError extends Error {})',
+    'class FooError extends SomethingEndingWithError {}',
+    '(class FooError extends SomethingEndingWithError {})',
+    'function makeError() {}',
+    '(function () {})',
+
+    // The following cases are currently allowed but could be disallowed in the
+    // future. This is technically an escape hatch.
+    'class Foo extends SomeLibrary.FooError {}',
+    '(class extends SomeLibrary.FooError {})',
+  ],
+  invalid: [
+    {
+      code: 'class SomethingEndingWithError {}',
+      errors: [{message: INVALID_SUPERCLASS_MESSAGE}],
+    },
+    {
+      code: '(class SomethingEndingWithError {})',
+      errors: [{message: INVALID_SUPERCLASS_MESSAGE}],
+    },
+    {
+      code: 'class Foo extends Error {}',
+      errors: [{message: INVALID_OWN_NAME_MESSAGE}],
+    },
+    {
+      code: '(class Foo extends Error {})',
+      errors: [{message: INVALID_OWN_NAME_MESSAGE}],
+    },
+    {
+      code: 'class Foo extends SomethingEndingWithError {}',
+      errors: [{message: INVALID_OWN_NAME_MESSAGE}],
+    },
+    {
+      code: '(class Foo extends SomethingEndingWithError {})',
+      errors: [{message: INVALID_OWN_NAME_MESSAGE}],
+    },
+    {
+      code: '(class extends Error {})',
+      errors: [{message: MISSING_OWN_NAME_MESSAGE}],
+    },
+    {
+      code: 'class SomethingEndingWithError extends C {}',
+      errors: [{message: INVALID_SUPERCLASS_MESSAGE}],
+    },
+    {
+      code: '(class SomethingEndingWithError extends C {})',
+      errors: [{message: INVALID_SUPERCLASS_MESSAGE}],
+    },
+    {
+      code: 'function SomethingEndingWithError() {}',
+      errors: [{message: INVALID_FUNCTION_NAME_MESSAGE}],
+    },
+    {
+      code: '(function SomethingEndingWithError() {})',
+      errors: [{message: INVALID_FUNCTION_NAME_MESSAGE}],
+    },
+
+    // The following cases are intentionally disallowed because the member
+    // expression `SomeLibrary.FooError` doesn't imply that the superclass is
+    // actually declared with the name `FooError`.
+    {
+      code: 'class SomethingEndingWithError extends SomeLibrary.FooError {}',
+      errors: [{message: INVALID_SUPERCLASS_MESSAGE}],
+    },
+    {
+      code: '(class SomethingEndingWithError extends SomeLibrary.FooError {})',
+      errors: [{message: INVALID_SUPERCLASS_MESSAGE}],
+    },
+  ],
+});

packages/eslint-plugin-react-native-community/__tests__/eslint-tester.js

@@ -0,0 +1,22 @@
+/**
+ * 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.
+ *
+ * @format
+ */
+
+'use strict';
+
+const ESLintTester = require('eslint').RuleTester;
+
+ESLintTester.setDefaultConfig({
+  parser: 'babel-eslint',
+  parserOptions: {
+    ecmaVersion: 6,
+    sourceType: 'module',
+  },
+});
+
+module.exports = ESLintTester;

packages/eslint-plugin-react-native-community/error-subclass-name.js

@@ -0,0 +1,66 @@
+/**
+ * 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.
+ *
+ * @format
+ */
+
+'use strict';
+
+module.exports = function rule(context) {
+  function classVisitor(node) {
+    const {superClass, id} = node;
+    const nodeIsError = isErrorLikeId(id);
+    const superIsError = isErrorLikeId(superClass);
+    if (nodeIsError && !superIsError) {
+      const idName = getNameFromId(id);
+      context.report({
+        node: superClass || id,
+        message: `'${idName}' must extend an error class (like 'Error') because its name is in PascalCase and ends with 'Error'.`,
+      });
+    } else if (superIsError && !nodeIsError) {
+      const idName = getNameFromId(id);
+      context.report({
+        node: id || node,
+        message: idName
+          ? `'${idName}' may not be the name of an error class. It should be in PascalCase and end with 'Error'.`
+          : "An error class should have a PascalCase name ending with 'Error'.",
+      });
+    }
+  }
+
+  function functionVisitor(node) {
+    const {id} = node;
+    const nodeIsError = isErrorLikeId(id);
+    if (nodeIsError) {
+      const idName = getNameFromId(id);
+      context.report({
+        node: id,
+        message: `'${idName}' is a reserved name. PascalCase names ending with 'Error' are reserved for error classes and may not be used for regular functions. Either rename this function or convert it to a class that extends 'Error'.`,
+      });
+    }
+  }
+
+  return {
+    ClassDeclaration: classVisitor,
+    ClassExpression: classVisitor,
+    FunctionExpression: functionVisitor,
+    FunctionDeclaration: functionVisitor,
+  };
+};
+
+// Checks whether `node` is an identifier (or similar name node) with a
+// PascalCase name ending with 'Error'.
+function isErrorLikeId(node) {
+  return (
+    node && node.type === 'Identifier' && /^([A-Z].*)?Error$/.test(node.name)
+  );
+}
+
+// If `node` is an identifier (or similar name node), returns its name as a
+// string. Otherwise returns null.
+function getNameFromId(node) {
+  return node ? node.name : null;
+}

packages/eslint-plugin-react-native-community/index.js

@@ -8,5 +8,6 @@
  */
 
 exports.rules = {
+  'error-subclass-name': require('./error-subclass-name'),
   'no-haste-imports': require('./no-haste-imports'),
 };

yarn.lock

@@ -1145,10 +1145,8 @@
     shell-quote "1.6.1"
     ws "^1.1.0"
 
-"@react-native-community/eslint-plugin@1.0.0":
+"@react-native-community/eslint-plugin@file:packages/eslint-plugin-react-native-community":
   version "1.0.0"
-  resolved "https://registry.yarnpkg.com/@react-native-community/eslint-plugin/-/eslint-plugin-1.0.0.tgz#ae9a430f2c5795debca491f15a989fce86ea75a0"
-  integrity sha512-GLhSN8dRt4lpixPQh+8prSCy6PYk/MT/mvji/ojAd5yshowDo6HFsimCSTD/uWAdjpUq91XK9tVdTNWfGRlKQA==
 
 "@reactions/component@^2.0.2":
   version "2.0.2"