fix(eslint-plugin): [typedef] allow array/object destructuring in for/of (#1570)

Author: a-tarasyuk

packages/eslint-plugin/docs/rules/typedef.md

@@ -76,6 +76,9 @@ Examples of **correct** code with `{ "arrayDestructuring": true }`:
 const [a]: number[] = [1];
 const [b]: [number] = [2];
 const [c, d]: [boolean, string] = [true, 'text'];
+
+for (const [key, val] of new Map([['key', 1]])) {
+}
 ```
 
 ### `arrowParameter`
@@ -144,6 +147,9 @@ Examples of **correct** code with `{ "objectDestructuring": true }`:
 ```ts
 const { length }: { length: number } = 'text';
 const [b, c]: [number, number] = Math.random() ? [1, 2] : [3, 4];
+
+for (const { key, val } of [{ key: 'key', val: 1 }]) {
+}
 ```
 
 ### `parameter`

packages/eslint-plugin/src/rules/typedef.ts

@@ -69,6 +69,31 @@ export default util.createRule<[Options], MessageIds>({
       return node.type === AST_NODE_TYPES.Identifier ? node.name : undefined;
     }
 
+    function isForOfStatementContext(
+      node: TSESTree.ArrayPattern | TSESTree.ObjectPattern,
+    ): boolean {
+      let current: TSESTree.Node | undefined = node.parent;
+      while (current) {
+        switch (current.type) {
+          case AST_NODE_TYPES.VariableDeclarator:
+          case AST_NODE_TYPES.VariableDeclaration:
+          case AST_NODE_TYPES.ObjectPattern:
+          case AST_NODE_TYPES.ArrayPattern:
+          case AST_NODE_TYPES.Property:
+            current = current.parent;
+            break;
+
+          case AST_NODE_TYPES.ForOfStatement:
+            return true;
+
+          default:
+            current = undefined;
+        }
+      }
+
+      return false;
+    }
+
     function checkParameters(params: TSESTree.Parameter[]): void {
       for (const param of params) {
         let annotationNode: TSESTree.Node | undefined;
@@ -102,7 +127,11 @@ export default util.createRule<[Options], MessageIds>({
 
     return {
       ArrayPattern(node): void {
-        if (options[OptionKeys.ArrayDestructuring] && !node.typeAnnotation) {
+        if (
+          options[OptionKeys.ArrayDestructuring] &&
+          !node.typeAnnotation &&
+          !isForOfStatementContext(node)
+        ) {
           report(node);
         }
       },
@@ -132,7 +161,11 @@ export default util.createRule<[Options], MessageIds>({
         }
       },
       ObjectPattern(node): void {
-        if (options[OptionKeys.ObjectDestructuring] && !node.typeAnnotation) {
+        if (
+          options[OptionKeys.ObjectDestructuring] &&
+          !node.typeAnnotation &&
+          !isForOfStatementContext(node)
+        ) {
           report(node);
         }
       },

packages/eslint-plugin/tests/rules/typedef.test.ts

@@ -38,6 +38,30 @@ ruleTester.run('typedef', rule, {
         },
       ],
     },
+    {
+      code: `for (const [key, val] of new Map([['key', 1]])) {}`,
+      options: [
+        {
+          arrayDestructuring: true,
+        },
+      ],
+    },
+    {
+      code: `for (const [[key]] of [[['key']]]) {}`,
+      options: [
+        {
+          arrayDestructuring: true,
+        },
+      ],
+    },
+    {
+      code: `for (const [[{ key }]] of [[[{ key: 'value' }]]]) {}`,
+      options: [
+        {
+          arrayDestructuring: true,
+        },
+      ],
+    },
     `let a: number;
     [a] = [1];`,
     // Arrow parameters
@@ -93,6 +117,22 @@ ruleTester.run('typedef', rule, {
         },
       ],
     },
+    {
+      code: `for (const {p1: {p2: { p3 }}} of [{p1: {p2: {p3: 'value'}}}]) {}`,
+      options: [
+        {
+          objectDestructuring: true,
+        },
+      ],
+    },
+    {
+      code: `for (const {p1: {p2: { p3: [key] }}} of [{p1: {p2: {p3: ['value']}}}]) {}`,
+      options: [
+        {
+          objectDestructuring: true,
+        },
+      ],
+    },
     {
       code: `const { a } = { a: 1 };`,
       options: [
@@ -101,6 +141,14 @@ ruleTester.run('typedef', rule, {
         },
       ],
     },
+    {
+      code: `for (const { key, val } of [{ key: 'key', val: 1 }]) {}`,
+      options: [
+        {
+          objectDestructuring: true,
+        },
+      ],
+    },
     // Function parameters
     `function receivesNumber(a: number): void { }`,
     `function receivesStrings(a: string, b: string): void { }`,