New: add new rule require-meta-schema (#87)

Author: bmish

Diff for: README.md

@@ -64,6 +64,7 @@ Name | ✔️ | 🛠 | Description
 [report-message-format](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/report-message-format.md) |  |  | enforce a consistent format for rule report messages
 [require-meta-docs-url](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/require-meta-docs-url.md) |  | 🛠 | require rules to implement a meta.docs.url property
 [require-meta-fixable](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/require-meta-fixable.md) | ✔️ |  | require rules to implement a meta.fixable property
+[require-meta-schema](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/require-meta-schema.md) |  | 🛠 | require rules to implement a meta.schema property
 [require-meta-type](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/require-meta-type.md) |  |  | require rules to implement a meta.type property
 [test-case-property-ordering](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/test-case-property-ordering.md) |  | 🛠 | Requires the properties of a test case to be placed in a consistent order
 [test-case-shorthand-strings](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/test-case-shorthand-strings.md) |  | 🛠 | Enforce consistent usage of shorthand strings for test cases with no options

Diff for: docs/rules/require-meta-schema.md

@@ -0,0 +1,53 @@
+# require rules to implement a meta.schema property (require-meta-schema)
+
+Defining a schema for each rule allows eslint to validate that configuration options are passed correctly. Even when there are no options for a rule, a schema should still be defined (as an empty array) so that eslint can validate that no data is passed to the rule.
+
+## Rule Details
+
+This rule requires ESLint rules to have a valid `meta.schema` property.
+
+Examples of **incorrect** code for this rule:
+
+```js
+/* eslint eslint-plugin/require-meta-schema: error */
+module.exports = {
+    meta: {},
+    create: function(context) { /* ... */}
+};
+
+module.exports = {
+    meta: { schema: null },
+    create: function(context) { /* ... */}
+};
+```
+
+Examples of **correct** code for this rule:
+
+```js
+/* eslint eslint-plugin/require-meta-type: error */
+module.exports = {
+    meta: { schema: [] }, // ensures no options are passed to the rule
+    create: function(context) { /* ... */}
+};
+
+module.exports = {
+    meta: {
+        schema: [
+            {
+                type: 'object',
+                properties: {
+                    exceptRange: {
+                        type: 'boolean'
+                    }
+                },
+                additionalProperties: false
+            }
+        ]
+    },
+    create: function(context) { /* ... */}
+};
+```
+
+## Further Reading
+
+* [working-with-rules#options-schemas](https://eslint.org/docs/developer-guide/working-with-rules#options-schemas)

Diff for: lib/rules/fixer-return.js

@@ -24,6 +24,7 @@ module.exports = {
     },
     type: 'problem',
     fixable: null,
+    schema: [],
   },
 
   create (context) {

Diff for: lib/rules/require-meta-docs-url.js

@@ -64,23 +64,6 @@ module.exports = {
       );
     }
 
-    /**
-     * Insert a given property into a given object literal.
-     * @param {SourceCodeFixer} fixer The fixer.
-     * @param {Node} node The ObjectExpression node to insert a property.
-     * @param {string} propertyText The property code to insert.
-     * @returns {void}
-     */
-    function insertProperty (fixer, node, propertyText) {
-      if (node.properties.length === 0) {
-        return fixer.replaceText(node, `{\n${propertyText}\n}`);
-      }
-      return fixer.insertTextAfter(
-        sourceCode.getLastToken(node.properties[node.properties.length - 1]),
-        `,\n${propertyText}`
-      );
-    }
-
     return {
       Program (node) {
         const info = util.getRuleInfo(node);
@@ -125,10 +108,10 @@ module.exports = {
                 return fixer.replaceText(urlPropNode.value, urlString);
               }
               if (docsPropNode && docsPropNode.value.type === 'ObjectExpression') {
-                return insertProperty(fixer, docsPropNode.value, `url: ${urlString}`);
+                return util.insertProperty(fixer, docsPropNode.value, `url: ${urlString}`, sourceCode);
               }
               if (!docsPropNode && metaNode && metaNode.type === 'ObjectExpression') {
-                return insertProperty(fixer, metaNode, `docs: {\nurl: ${urlString}\n}`);
+                return util.insertProperty(fixer, metaNode, `docs: {\nurl: ${urlString}\n}`, sourceCode);
               }
             }
             return null;

Diff for: lib/rules/require-meta-schema.js

@@ -0,0 +1,65 @@
+'use strict';
+
+const utils = require('../utils');
+
+// ------------------------------------------------------------------------------
+// Rule Definition
+// ------------------------------------------------------------------------------
+
+module.exports = {
+  meta: {
+    docs: {
+      description: 'require rules to implement a meta.schema property',
+      category: 'Rules',
+      recommended: false, // TODO: enable it in a major release.
+    },
+    type: 'suggestion',
+    fixable: 'code',
+    schema: [
+      {
+        type: 'object',
+        properties: {
+          exceptRange: {
+            type: 'boolean',
+          },
+        },
+        additionalProperties: false,
+      },
+    ],
+    messages: {
+      missing: '`meta.schema` is required (use [] if rule has no schema).',
+      wrongType: '`meta.schema` should be an array (use [] if rule has no schema).',
+    },
+  },
+
+  create (context) {
+    const sourceCode = context.getSourceCode();
+    const info = utils.getRuleInfo(sourceCode.ast, sourceCode.scopeManager);
+
+    return {
+      Program () {
+        if (info === null || info.meta === null) {
+          return;
+        }
+
+        const metaNode = info.meta;
+        const schemaNode =
+          metaNode &&
+          metaNode.properties &&
+          metaNode.properties.find(p => p.type === 'Property' && utils.getKeyName(p) === 'schema');
+
+        if (!schemaNode) {
+          context.report({
+            node: metaNode,
+            messageId: 'missing',
+            fix (fixer) {
+              return utils.insertProperty(fixer, metaNode, 'schema: []', sourceCode);
+            },
+          });
+        } else if (schemaNode.value.type !== 'ArrayExpression') {
+          context.report({ node: schemaNode.value, messageId: 'wrongType' });
+        }
+      },
+    };
+  },
+};

Diff for: lib/utils.js

@@ -322,4 +322,21 @@ module.exports = {
       .reduce((allRefs, refsForVariable) => allRefs.concat(refsForVariable), [])
       .map(ref => ref.identifier));
   },
+
+  /**
+   * Insert a given property into a given object literal.
+   * @param {SourceCodeFixer} fixer The fixer.
+   * @param {Node} node The ObjectExpression node to insert a property.
+   * @param {string} propertyText The property code to insert.
+   * @returns {void}
+   */
+  insertProperty (fixer, node, propertyText, sourceCode) {
+    if (node.properties.length === 0) {
+      return fixer.replaceText(node, `{\n${propertyText}\n}`);
+    }
+    return fixer.insertTextAfter(
+      sourceCode.getLastToken(node.properties[node.properties.length - 1]),
+      `,\n${propertyText}`
+    );
+  },
 };

Diff for: tests/lib/rules/require-meta-schema.js

@@ -0,0 +1,76 @@
+'use strict';
+
+// ------------------------------------------------------------------------------
+// Requirements
+// ------------------------------------------------------------------------------
+
+const rule = require('../../../lib/rules/require-meta-schema');
+const RuleTester = require('eslint').RuleTester;
+
+// ------------------------------------------------------------------------------
+// Tests
+// ------------------------------------------------------------------------------
+
+const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 6 } });
+ruleTester.run('require-meta-schema', rule, {
+  valid: [
+    `
+      module.exports = {
+        meta: { schema: [] },
+        create(context) {}
+      };
+    `,
+    `
+      module.exports = {
+        meta: { schema: [ { "enum": ["always", "never"] } ] },
+        create(context) {}
+      };
+    `,
+  ],
+
+  invalid: [
+    {
+      code: `
+        module.exports = {
+          meta: {},
+          create(context) {}
+        };
+      `,
+      output: `
+        module.exports = {
+          meta: {
+schema: []
+},
+          create(context) {}
+        };
+      `,
+      errors: [{ messageId: 'missing', type: 'ObjectExpression' }],
+    },
+    {
+      code: `
+        module.exports = {
+          meta: { type: 'problem' },
+          create(context) {}
+        };
+      `,
+      output: `
+        module.exports = {
+          meta: { type: 'problem',
+schema: [] },
+          create(context) {}
+        };
+      `,
+      errors: [{ messageId: 'missing', type: 'ObjectExpression' }],
+    },
+    {
+      code: `
+        module.exports = {
+          meta: { schema: null },
+          create(context) {}
+        };
+      `,
+      output: null,
+      errors: [{ messageId: 'wrongType', type: 'Literal' }],
+    },
+  ],
+});