fix(eslint-plugin): [method-signature-style] correct fixer for overloads in an object literal type (typescript-eslint#2708)

a-tarasyuk · web-flow · commit 0763913c4a0d · 2020-10-25T14:58:27.000-07:00
diff --git a/packages/eslint-plugin/src/rules/method-signature-style.ts b/packages/eslint-plugin/src/rules/method-signature-style.ts
@@ -118,15 +118,20 @@ export default util.createRule<Options, MessageIds>({
           return;
         }
 
-        const duplicatedKeyMethodNodes: TSESTree.TSMethodSignature[] =
-          methodNode.parent?.type === AST_NODE_TYPES.TSInterfaceBody
-            ? methodNode.parent.body.filter(
-                (element): element is TSESTree.TSMethodSignature =>
-                  element.type === AST_NODE_TYPES.TSMethodSignature &&
-                  element !== methodNode &&
-                  getMethodKey(element) === getMethodKey(methodNode),
-              )
+        const parent = methodNode.parent;
+        const members =
+          parent?.type === AST_NODE_TYPES.TSInterfaceBody
+            ? parent.body
+            : parent?.type === AST_NODE_TYPES.TSTypeLiteral
+            ? parent.members
             : [];
+
+        const duplicatedKeyMethodNodes: TSESTree.TSMethodSignature[] = members.filter(
+          (element): element is TSESTree.TSMethodSignature =>
+            element.type === AST_NODE_TYPES.TSMethodSignature &&
+            element !== methodNode &&
+            getMethodKey(element) === getMethodKey(methodNode),
+        );
         const isParentModule = isNodeParentModuleDeclaration(methodNode);
 
         if (duplicatedKeyMethodNodes.length > 0) {
diff --git a/packages/eslint-plugin/tests/rules/method-signature-style.test.ts b/packages/eslint-plugin/tests/rules/method-signature-style.test.ts
@@ -371,5 +371,61 @@ interface Foo {
         },
       ],
     },
+    {
+      code: noFormat`
+type Foo = {
+  foo(): one;
+  foo(): two;
+  foo(): three;
+}
+      `,
+      output: noFormat`
+type Foo = {
+  foo: (() => one) & (() => two) & (() => three);
+}
+      `,
+      errors: [
+        {
+          messageId: 'errorMethod',
+          line: 3,
+        },
+        {
+          messageId: 'errorMethod',
+          line: 4,
+        },
+        {
+          messageId: 'errorMethod',
+          line: 5,
+        },
+      ],
+    },
+    {
+      code: noFormat`
+declare const Foo: {
+  foo(): one;
+  foo(): two;
+  foo(): three;
+}
+      `,
+      output: noFormat`
+declare const Foo: {
+  foo: (() => one) & (() => two) & (() => three);
+}
+      `,
+      errors: [
+        {
+          messageId: 'errorMethod',
+          line: 3,
+        },
+        {
+          messageId: 'errorMethod',
+          line: 4,
+        },
+        {
+          messageId: 'errorMethod',
+          line: 5,
+        },
+      ],
+    },
   ],
 });
