From 5c40d01056cd1ca9e0ecc5c90a0d4b164931af30 Mon Sep 17 00:00:00 2001
From: Jonathan Delgado <jonathanrdelgado@gmail.com>
Date: Sat, 15 Jun 2019 20:26:21 -0700
Subject: [PATCH] fix(eslint-plugin): [no-magic-numbers] add support for enums
 (#543)

---
 .../docs/rules/no-magic-numbers.md            | 24 +++++++++++++
 .../src/rules/no-magic-numbers.ts             | 24 ++++++++++++-
 .../tests/rules/no-magic-numbers.test.ts      | 36 +++++++++++++++++++
 .../eslint-plugin/typings/eslint-rules.d.ts   |  1 +
 4 files changed, 84 insertions(+), 1 deletion(-)

diff --git a/packages/eslint-plugin/docs/rules/no-magic-numbers.md b/packages/eslint-plugin/docs/rules/no-magic-numbers.md
index 2ff5aab519d..b5a1e92fd09 100644
--- a/packages/eslint-plugin/docs/rules/no-magic-numbers.md
+++ b/packages/eslint-plugin/docs/rules/no-magic-numbers.md
@@ -41,4 +41,28 @@ Examples of **correct** code for the `{ "ignoreNumericLiteralTypes": true }` opt
 type SmallPrimes = 2 | 3 | 5 | 7 | 11;
 ```
 
+### ignoreEnums
+
+A boolean to specify if enums used in Typescript are considered okay. `false` by default.
+
+Examples of **incorrect** code for the `{ "ignoreEnum": false }` option:
+
+```ts
+/*eslint @typescript-eslint/no-magic-numbers: ["error", { "ignoreEnum": false }]*/
+
+enum foo = {
+    SECOND = 1000,
+}
+```
+
+Examples of **correct** code for the `{ "ignoreEnum": true }` option:
+
+```ts
+/*eslint @typescript-eslint/no-magic-numbers: ["error", { "ignoreEnum": true }]*/
+
+enum foo = {
+    SECOND = 1000,
+}
+```
+
 <sup>Taken with ❤️ [from ESLint core](https://github.com/eslint/eslint/blob/master/docs/rules/no-magic-numbers.md)</sup>
diff --git a/packages/eslint-plugin/src/rules/no-magic-numbers.ts b/packages/eslint-plugin/src/rules/no-magic-numbers.ts
index f298bfd68f2..1880aa19c9d 100644
--- a/packages/eslint-plugin/src/rules/no-magic-numbers.ts
+++ b/packages/eslint-plugin/src/rules/no-magic-numbers.ts
@@ -29,6 +29,9 @@ export default util.createRule<Options, MessageIds>({
           ignoreNumericLiteralTypes: {
             type: 'boolean',
           },
+          ignoreEnums: {
+            type: 'boolean',
+          },
         },
       },
     ],
@@ -41,6 +44,7 @@ export default util.createRule<Options, MessageIds>({
       enforceConst: false,
       detectObjects: false,
       ignoreNumericLiteralTypes: false,
+      ignoreEnums: false,
     },
   ],
   create(context, [options]) {
@@ -85,6 +89,19 @@ export default util.createRule<Options, MessageIds>({
       return false;
     }
 
+    /**
+     * Checks if the node parent is a Typescript enum member
+     * @param node the node to be validated.
+     * @returns true if the node parent is a Typescript enum member
+     * @private
+     */
+    function isParentTSEnumDeclaration(node: TSESTree.Node): boolean {
+      return (
+        typeof node.parent !== 'undefined' &&
+        node.parent.type === AST_NODE_TYPES.TSEnumMember
+      );
+    }
+
     /**
      * Checks if the node parent is a Typescript literal type
      * @param node the node to be validated.
@@ -133,7 +150,12 @@ export default util.createRule<Options, MessageIds>({
 
     return {
       Literal(node) {
-        // Check TypeScript specific nodes
+        // Check if the node is a TypeScript enum declaration
+        if (options.ignoreEnums && isParentTSEnumDeclaration(node)) {
+          return;
+        }
+
+        // Check TypeScript specific nodes for Numeric Literal
         if (
           options.ignoreNumericLiteralTypes &&
           isNumber(node) &&
diff --git a/packages/eslint-plugin/tests/rules/no-magic-numbers.test.ts b/packages/eslint-plugin/tests/rules/no-magic-numbers.test.ts
index 2b184ad76b2..09b6c35d0b4 100644
--- a/packages/eslint-plugin/tests/rules/no-magic-numbers.test.ts
+++ b/packages/eslint-plugin/tests/rules/no-magic-numbers.test.ts
@@ -33,6 +33,14 @@ ruleTester.run('no-magic-numbers', rule, {
       code: 'type Foo = 1 | -1;',
       options: [{ ignoreNumericLiteralTypes: true }],
     },
+    {
+      code: 'enum foo { SECOND = 1000 }',
+      options: [{ ignoreEnums: true }],
+    },
+    {
+      code: 'enum foo { SECOND = 1000, NUM = "0123456789" }',
+      options: [{ ignoreEnums: true }],
+    },
   ],
 
   invalid: [
@@ -130,5 +138,33 @@ ruleTester.run('no-magic-numbers', rule, {
         },
       ],
     },
+    {
+      code: 'enum foo { SECOND = 1000 }',
+      options: [{ ignoreEnums: false }],
+      errors: [
+        {
+          messageId: 'noMagic',
+          data: {
+            raw: '1000',
+          },
+          line: 1,
+          column: 21,
+        },
+      ],
+    },
+    {
+      code: 'enum foo { SECOND = 1000, NUM = "0123456789" }',
+      options: [{ ignoreEnums: false }],
+      errors: [
+        {
+          messageId: 'noMagic',
+          data: {
+            raw: '1000',
+          },
+          line: 1,
+          column: 21,
+        },
+      ],
+    },
   ],
 });
diff --git a/packages/eslint-plugin/typings/eslint-rules.d.ts b/packages/eslint-plugin/typings/eslint-rules.d.ts
index 98ee285d1a2..774f0842aa5 100644
--- a/packages/eslint-plugin/typings/eslint-rules.d.ts
+++ b/packages/eslint-plugin/typings/eslint-rules.d.ts
@@ -180,6 +180,7 @@ declare module 'eslint/lib/rules/no-magic-numbers' {
         enforceConst?: boolean;
         detectObjects?: boolean;
         ignoreNumericLiteralTypes?: boolean;
+        ignoreEnums?: boolean;
       }
     ],
     {