Add new rules no-missing-message-ids and no-unused-message-ids

README.md

@@ -67,8 +67,10 @@ Name | ✔️ | 🛠 | 💡 | Description
 [no-deprecated-context-methods](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/no-deprecated-context-methods.md) | ✔️ | 🛠 |  | disallow usage of deprecated methods on rule context objects
 [no-deprecated-report-api](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/no-deprecated-report-api.md) | ✔️ | 🛠 |  | disallow the version of `context.report()` with multiple arguments
 [no-identical-tests](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/no-identical-tests.md) | ✔️ | 🛠 |  | disallow identical tests
+[no-missing-message-ids](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/no-missing-message-ids.md) |  |  |  | disallow `messageId`s that are missing from `meta.messages`
 [no-missing-placeholders](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/no-missing-placeholders.md) | ✔️ |  |  | disallow missing placeholders in rule report messages
 [no-only-tests](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/no-only-tests.md) | ✔️ |  | 💡 | disallow the test case property `only`
+[no-unused-message-ids](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/no-unused-message-ids.md) |  |  |  | disallow unused `messageId`s in `meta.messages`
 [no-unused-placeholders](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/no-unused-placeholders.md) | ✔️ |  |  | disallow unused placeholders in rule report messages
 [no-useless-token-range](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/no-useless-token-range.md) | ✔️ | 🛠 |  | disallow unnecessary calls to `sourceCode.getFirstToken()` and `sourceCode.getLastToken()`
 [prefer-message-ids](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/prefer-message-ids.md) |  |  |  | require using `messageId` instead of `message` to report rule violations

docs/rules/no-missing-message-ids.md

@@ -0,0 +1,59 @@
+# Disallow `messageId`s that are missing from `meta.messages` (no-missing-message-ids)
+
+When using `meta.messages` and `messageId` to report rule violations, it's possible to mistakenly use a `messageId` that doesn't exist in `meta.messages`.
+
+## Rule Details
+
+Examples of **incorrect** code for this rule:
+
+```js
+/* eslint eslint-plugin/no-missing-message-ids: error */
+
+module.exports = {
+  meta: {
+    messages: {
+      foo: 'hello world',
+    },
+  },
+  create(context) {
+    return {
+      CallExpression(node) {
+        context.report({
+          node,
+          messageId: 'abc',
+        });
+      },
+    };
+  },
+};
+```
+
+Examples of **correct** code for this rule:
+
+```js
+/* eslint eslint-plugin/no-missing-message-ids: error */
+
+module.exports = {
+  meta: {
+    messages: {
+      foo: 'hello world',
+    },
+  },
+  create(context) {
+    return {
+      CallExpression(node) {
+        context.report({
+          node,
+          messageId: 'foo',
+        });
+      },
+    };
+  },
+};
+```
+
+## Further Reading
+
+* [messageIds API](https://eslint.org/docs/developer-guide/working-with-rules#messageids)
+* [no-unused-message-ids](./no-unused-message-ids.md) rule
+* [prefer-message-ids](./prefer-message-ids.md) rule

docs/rules/no-unused-message-ids.md

@@ -0,0 +1,60 @@
+# Disallow unused `messageId`s in `meta.messages` (no-unused-message-ids)
+
+When using `meta.messages` and `messageId` to report rule violations, it's possible to mistakenly leave a message in `meta.messages` that is never used.
+
+## Rule Details
+
+Examples of **incorrect** code for this rule:
+
+```js
+/* eslint eslint-plugin/no-unused-message-ids: error */
+
+module.exports = {
+  meta: {
+    messages: {
+      foo: 'hello world',
+      bar: 'lorem ipsum', // this message is never used
+    },
+  },
+  create(context) {
+    return {
+      CallExpression(node) {
+        context.report({
+          node,
+          messageId: 'foo',
+        });
+      },
+    };
+  },
+};
+```
+
+Examples of **correct** code for this rule:
+
+```js
+/* eslint eslint-plugin/no-unused-message-ids: error */
+
+module.exports = {
+  meta: {
+    messages: {
+      foo: 'hello world',
+    },
+  },
+  create(context) {
+    return {
+      CallExpression(node) {
+        context.report({
+          node,
+          messageId: 'foo',
+        });
+      },
+    };
+  },
+};
+```
+
+## Further Reading
+
+* [messageIds API](https://eslint.org/docs/developer-guide/working-with-rules#messageids)
+* [no-missing-message-ids](./no-missing-message-ids.md) rule
+* [prefer-message-ids](./prefer-message-ids.md) rule

docs/rules/prefer-message-ids.md

@@ -55,3 +55,5 @@ module.exports = {
 ## Further Reading
 
 * [messageIds API](https://eslint.org/docs/developer-guide/working-with-rules#messageids)
+* [no-invalid-message-ids](./no-invalid-message-ids.md) rule
+* [no-missing-message-ids](./no-missing-message-ids.md) rule

lib/rules/no-missing-message-ids.js

@@ -0,0 +1,88 @@
+'use strict';
+
+const utils = require('../utils');
+
+// ------------------------------------------------------------------------------
+// Rule Definition
+// ------------------------------------------------------------------------------
+
+/** @type {import('eslint').Rule.RuleModule} */
+module.exports = {
+  meta: {
+    type: 'problem',
+    docs: {
+      description:
+        'disallow `messageId`s that are missing from `meta.messages`',
+      category: 'Rules',
+      recommended: false,
+      url: 'https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/tree/HEAD/docs/rules/no-missing-message-ids.md',
+    },
+    fixable: null,
+    schema: [],
+    messages: {
+      missingMessage: '`meta.messages` is missing this `messageId`.',
+    },
+  },
+
+  create(context) {
+    const sourceCode = context.getSourceCode();
+    const { scopeManager } = sourceCode;
+    const ruleInfo = utils.getRuleInfo(sourceCode);
+
+    const messagesNode = utils.getMessagesNode(ruleInfo, scopeManager);
+
+    let contextIdentifiers;
+
+    if (!messagesNode || messagesNode.type !== 'ObjectExpression') {
+      // If we can't find `meta.messages`, disable the rule.
+      return {};
+    }
+
+    return {
+      Program(ast) {
+        contextIdentifiers = utils.getContextIdentifiers(scopeManager, ast);
+      },
+
+      CallExpression(node) {
+        // Check for messageId properties used in known calls to context.report();
+        if (
+          node.callee.type === 'MemberExpression' &&
+          contextIdentifiers.has(node.callee.object) &&
+          node.callee.property.type === 'Identifier' &&
+          node.callee.property.name === 'report'
+        ) {
+          const reportInfo = utils.getReportInfo(node.arguments, context);
+          if (!reportInfo) {
+            return;
+          }
+
+          const reportMessagesAndDataArray =
+            utils.collectReportViolationAndSuggestionData(reportInfo);
+          for (const { messageId } of reportMessagesAndDataArray.filter(
+            (obj) => obj.messageId
+          )) {
+            const values =
+              messageId.type === 'Literal'
+                ? [messageId]
+                : utils.findPossibleVariableValues(messageId, scopeManager);
+
+            // Look for any possible string values we found for this messageId.
+            values.forEach((val) => {
+              if (
+                val.type === 'Literal' &&
+                val.value !== null &&
+                val.value !== '' &&
+                !utils.getMessageIdNodeById(val.value, ruleInfo, scopeManager)
+              )
+                // Couldn't find this messageId in `meta.messages`.
+                context.report({
+                  node: val,
+                  messageId: 'missingMessage',
+                });
+            });
+          }
+        }
+      },
+    };
+  },
+};

lib/rules/no-unused-message-ids.js

@@ -0,0 +1,113 @@
+'use strict';
+
+const utils = require('../utils');
+
+// ------------------------------------------------------------------------------
+// Rule Definition
+// ------------------------------------------------------------------------------
+
+/** @type {import('eslint').Rule.RuleModule} */
+module.exports = {
+  meta: {
+    type: 'problem',
+    docs: {
+      description: 'disallow unused `messageId`s in `meta.messages`',
+      category: 'Rules',
+      recommended: false,
+      url: 'https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/tree/HEAD/docs/rules/no-unused-message-ids.md',
+    },
+    fixable: null,
+    schema: [],
+    messages: {
+      unusedMessage: 'This message is never used.',
+    },
+  },
+
+  create(context) {
+    const sourceCode = context.getSourceCode();
+    const { scopeManager } = sourceCode;
+    const info = utils.getRuleInfo(sourceCode);
+
+    const messageIdsUsed = new Set();
+    let contextIdentifiers;
+    let shouldPerformUnusedCheck = true;
+
+    const messageIdNodes = utils.getMessageIdNodes(info, scopeManager);
+    if (!messageIdNodes) {
+      // If we can't find `meta.messages`, disable the rule.
+      return {};
+    }
+
+    return {
+      Program(ast) {
+        contextIdentifiers = utils.getContextIdentifiers(scopeManager, ast);
+      },
+
+      'Program:exit'() {
+        if (shouldPerformUnusedCheck) {
+          for (const messageIdNode of messageIdNodes.filter(
+            (node) => !messageIdsUsed.has(node.key.name)
+          )) {
+            context.report({
+              node: messageIdNode,
+              messageId: 'unusedMessage',
+            });
+          }
+        }
+      },
+
+      CallExpression(node) {
+        // Check for messageId properties used in known calls to context.report();
+        if (
+          node.callee.type === 'MemberExpression' &&
+          contextIdentifiers.has(node.callee.object) &&
+          node.callee.property.type === 'Identifier' &&
+          node.callee.property.name === 'report'
+        ) {
+          const reportInfo = utils.getReportInfo(node.arguments, context);
+          if (!reportInfo) {
+            return;
+          }
+
+          const reportMessagesAndDataArray =
+            utils.collectReportViolationAndSuggestionData(reportInfo);
+          for (const { messageId } of reportMessagesAndDataArray.filter(
+            (obj) => obj.messageId
+          )) {
+            const values =
+              messageId.type === 'Literal'
+                ? [messageId]
+                : utils.findPossibleVariableValues(messageId, scopeManager);
+            if (
+              values.length === 0 ||
+              values.some((val) => val.type !== 'Literal')
+            ) {
+              // When a dynamic messageId is used and we can't detect its value, disable the rule to avoid false positives.
+              shouldPerformUnusedCheck = false;
+            }
+            values.forEach((val) => messageIdsUsed.add(val.value));
+          }
+        }
+      },
+
+      Property(node) {
+        // In order to reduce false positives, we will also check for messageId properties anywhere in the file.
+        // This is helpful especially in the event that helper functions are used for reporting violations.
+        if (node.key.type === 'Identifier' && node.key.name === 'messageId') {
+          const values =
+            node.value.type === 'Literal'
+              ? [node.value]
+              : utils.findPossibleVariableValues(node.value, scopeManager);
+          if (
+            values.length === 0 ||
+            values.some((val) => val.type !== 'Literal')
+          ) {
+            // When a dynamic messageId is used and we can't detect its value, disable the rule to avoid false positives.
+            shouldPerformUnusedCheck = false;
+          }
+          values.forEach((val) => messageIdsUsed.add(val.value));
+        }
+      },
+    };
+  },
+};