typescript-eslint · lcharlois-neotys · Oct 23, 2023 · Oct 23, 2023 · Oct 23, 2023 · Oct 24, 2023
diff --git a/packages/eslint-plugin/docs/rules/no-misused-spread.md b/packages/eslint-plugin/docs/rules/no-misused-spread.md
@@ -0,0 +1,45 @@
+---
+description: "Disallow spread operator that shouldn't be spread most of the time."
+---
+
+> 🛑 This file is source code, not the primary documentation location! 🛑
+>
+> See **https://typescript-eslint.io/rules/no-misused-spread** for documentation.
+
+Spreading a function is almost always a mistake. Most of the time you forgot to call the function.
+
+## Examples
+
+<!--tabs-->
+
+### ❌ Incorrect
+
+```ts
+const fn = () => ({ name: 'name' });
+const obj = {
+  ...fn,
+  value: 1,
+};
+```
+
+```ts
+const fn = () => ({ value: 33 });
+const otherFn = ({ value: number }) => ({ value: value });
+otherFn({ ...fn });
+```
+
+### ✅ Correct
+
+```ts
+const fn = () => ({ name: 'name' });
+const obj = {
+  ...fn(),
+  value: 1,
+};
+```
+
+```ts
+const fn = () => ({ value: 33 });
+const otherFn = ({ value: number }) => ({ value: value });
+otherFn({ ...fn() });
+```
diff --git a/packages/eslint-plugin/src/configs/all.ts b/packages/eslint-plugin/src/configs/all.ts
@@ -97,6 +97,7 @@ export = {
     '@typescript-eslint/no-misused-new': 'error',
     '@typescript-eslint/no-misused-promises': 'error',
     '@typescript-eslint/no-mixed-enums': 'error',
+    '@typescript-eslint/no-misused-spread': 'error',
     '@typescript-eslint/no-namespace': 'error',
     '@typescript-eslint/no-non-null-asserted-nullish-coalescing': 'error',
     '@typescript-eslint/no-non-null-asserted-optional-chain': 'error',

diff --git a/packages/eslint-plugin/src/configs/stylistic-type-checked.ts b/packages/eslint-plugin/src/configs/stylistic-type-checked.ts
@@ -23,6 +23,7 @@ export = {
     '@typescript-eslint/no-empty-function': 'error',
     '@typescript-eslint/no-empty-interface': 'error',
     '@typescript-eslint/no-inferrable-types': 'error',
+    '@typescript-eslint/no-misused-spread': 'error',
     '@typescript-eslint/non-nullable-type-assertion-style': 'error',
     '@typescript-eslint/prefer-for-of': 'error',
     '@typescript-eslint/prefer-function-type': 'error',

diff --git a/packages/eslint-plugin/src/rules/index.ts b/packages/eslint-plugin/src/rules/index.ts
@@ -61,6 +61,7 @@ import noMagicNumbers from './no-magic-numbers';
 import noMeaninglessVoidOperator from './no-meaningless-void-operator';
 import noMisusedNew from './no-misused-new';
 import noMisusedPromises from './no-misused-promises';
+import noMisusedSpread from './no-misused-spread';
 import noMixedEnums from './no-mixed-enums';
 import noNamespace from './no-namespace';
 import noNonNullAssertedNullishCoalescing from './no-non-null-asserted-nullish-coalescing';
@@ -198,6 +199,7 @@ export default {
   'no-meaningless-void-operator': noMeaninglessVoidOperator,
   'no-misused-new': noMisusedNew,
   'no-misused-promises': noMisusedPromises,
+  'no-misused-spread': noMisusedSpread,
   'no-mixed-enums': noMixedEnums,
   'no-namespace': noNamespace,
   'no-non-null-asserted-nullish-coalescing': noNonNullAssertedNullishCoalescing,

diff --git a/packages/eslint-plugin/src/rules/no-misused-spread.ts b/packages/eslint-plugin/src/rules/no-misused-spread.ts
@@ -0,0 +1,46 @@
+import { type TSESLint, type TSESTree } from '@typescript-eslint/utils';
+
+import { createRule, getParserServices } from '../util';
+
+type MessageIds = 'forbiddenFunctionSpread';
+
+export default createRule<[], MessageIds>({
+  defaultOptions: [],
+  name: 'no-misused-spread',
+  meta: {
+    docs: {
+      description:
+        "Disallow spread operator that shouldn't be spread most of the time",
-        "Disallow spread operator that shouldn't be spread most of the time",
+        "Disallow using the spread operator on values that can't be spread",
-        "Disallow spread operator that shouldn't be spread most of the time",
+        "Disallow using the spread operator on values that can't be spread",
+      recommended: 'stylistic',
+      requiresTypeChecking: true,
+    },
+    messages: {
+      forbiddenFunctionSpread:
+        'Spreading a function is almost always a mistake. Did you forget to call the function?',
-        'Spreading a function is almost always a mistake. Did you forget to call the function?',
+        'Spreading a function with no custom properties does nothing. Did you forget to call the function?',
-        'Spreading a function is almost always a mistake. Did you forget to call the function?',
+        'Spreading a function with no custom properties does nothing. Did you forget to call the function?',
+    },
+    schema: [],
+    type: 'suggestion',
+  },
+  create: (context): TSESLint.RuleListener => {
+    const listener = (node: TSESTree.SpreadElement): void => {
+      const services = getParserServices(context);
+      const checker = services.program.getTypeChecker();
+
+      const tsNode = services.esTreeNodeToTSNodeMap.get(node.argument);
+      const type = checker.getTypeAtLocation(tsNode);
-      const checker = services.program.getTypeChecker();
-
-      const tsNode = services.esTreeNodeToTSNodeMap.get(node.argument);
-      const type = checker.getTypeAtLocation(tsNode);
+      const type = services.getTypeAtLocation(node.argument);
-      const checker = services.program.getTypeChecker();
-
-      const tsNode = services.esTreeNodeToTSNodeMap.get(node.argument);
-      const type = checker.getTypeAtLocation(tsNode);
+      const type = services.getTypeAtLocation(node.argument);
+
+      if (
+        type.getProperties().length === 0 &&
+        type.getCallSignatures().length > 0
+      ) {
+        context.report({
+          node,
+          messageId: 'forbiddenFunctionSpread',
+        });
+      }
+    };
+    return {
+      SpreadElement: listener,
+    };
+  },
+});
diff --git a/packages/eslint-plugin/tests/rules/no-misused-spread.test.ts b/packages/eslint-plugin/tests/rules/no-misused-spread.test.ts
@@ -0,0 +1,106 @@
+import { RuleTester } from '@typescript-eslint/rule-tester';
+
+import rule from '../../src/rules/no-misused-spread';
+import { getFixturesRootDir } from '../RuleTester';
+
+const rootDir = getFixturesRootDir();
+const ruleTester = new RuleTester({
+  parser: '@typescript-eslint/parser',
+  parserOptions: {
+    tsconfigRootDir: rootDir,
+    project: './tsconfig.json',
+  },
+});
+
+ruleTester.run('no-misused-spread', rule, {
+  valid: [
+    `
+const a = () => ({ value: 33 });
+const b = {
+  ...a(),
+  name: 'name',
+};
+    `,
+    `
+const a = (x: number) => ({ value: x });
+const b = {
+  ...a(42),
+  name: 'name',
+};
+    `,
+    `
+interface FuncWithProps {
+  property?: string;
+  (): number;
+}
+const funcWithProps: FuncWithProps = () => 1;
+funcWithProps.property = 'foo';
+const spreadFuncWithProps = { ...funcWithProps };
+    `,
+    `
+type FuncWithProps = {
+  property?: string;
+  (): number;
+};
+const funcWithProps: FuncWithProps = () => 1;
+funcWithProps.property = 'foo';
+const spreadFuncWithProps = { ...funcWithProps };
+    `,
+    `
+const a = { value: 33 };
+const b = {
+  ...a,
+  name: 'name',
+};
+    `,
+    `
+const a = {};
+const b = {
+  ...a,
+  name: 'name',
+};
+    `,
+    `
+const a = () => ({ value: 33 });
+const b = ({ value: number }) => ({ value: value });
+b({ ...a() });
+    `,
+    `
+const a = [33];
+const b = {
+  ...a,
+  name: 'name',
+};
+    `,
+  ],
+  invalid: [
+    {
+      code: `
+const a = () => ({ value: 33 });
+const b = {
+  ...a,
+  name: 'name',
+};
+      `,
+      errors: [{ line: 4, column: 3, messageId: 'forbiddenFunctionSpread' }],
+    },
+    {
+      code: `
+const a = (x: number) => ({ value: x });
+const b = {
+  ...a,
+  name: 'name',
+};
+      `,
+      errors: [{ line: 4, column: 3, messageId: 'forbiddenFunctionSpread' }],
+    },
+    {
+      code: `
+const a = () => ({ value: 33 });
+const b = ({ value: number }) => ({ value: value });
+b({ ...a });
+      `,
+      errors: [{ line: 4, column: 5, messageId: 'forbiddenFunctionSpread' }],
+    },
+  ],
+});
diff --git a/packages/eslint-plugin/tests/schema-snapshots/no-misused-spread.shot b/packages/eslint-plugin/tests/schema-snapshots/no-misused-spread.shot