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feat: support TS syntax in max-params (#19557)
* feat: support TS syntax in `max-params` * docs: add countVoidThis option * docs: add countVoidThis option * chore: fix lint * docs: udpate examples * docs: revert formatting * refactor: simplify logic * refactor: simplify logic * docs: fix examples * docs: update docs/src/rules/max-params.md Co-authored-by: Milos Djermanovic <[email protected]> * docs: update types * test: add more test cases * test: add more test cases * chore: update tests * chore: remove unwanted changes --------- Co-authored-by: Milos Djermanovic <[email protected]>
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Lines changed: 260 additions & 7 deletions

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‎docs/src/rules/max-params.md‎

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@@ -29,6 +29,7 @@ This rule enforces a maximum number of parameters allowed in function definition
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This rule has a number or object option:
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* `"max"` (default `3`) enforces a maximum number of parameters in function definitions
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* `"countVoidThis"` (default `false`) counts a `this` declaration when the type is `void` (TypeScript only)
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**Deprecated:** The object property `maximum` is deprecated; please use the object property `max` instead.
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@@ -69,3 +70,63 @@ let foo2 = (bar, baz, qux) => {
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```
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:::
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### countVoidThis (TypeScript only)
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This rule has a TypeScript-specific option `countVoidThis` that allows you to count a `this` declaration when the type is `void`.
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Examples of **correct** TypeScript code for this rule with the default `{ "countVoidThis": false }` option:
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:::correct
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```ts
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/*eslint max-params: ["error", { "max": 2, "countVoidThis": false }]*/
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function hasNoThis(this: void, first: string, second: string) {
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// ...
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}
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```
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:::
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Examples of **incorrect** TypeScript code for this rule with the default `{ "countVoidThis": false }` option:
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:::incorrect
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```ts
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/*eslint max-params: ["error", { "max": 2, "countVoidThis": false }]*/
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function hasNoThis(this: void, first: string, second: string, third: string) {
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// ...
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}
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```
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:::
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Examples of **correct** TypeScript code for this rule with the `{ "countVoidThis": true }` option:
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:::correct
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```ts
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/*eslint max-params: ["error", { "max": 2, "countVoidThis": true }]*/
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function hasNoThis(this: void, first: string) {
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// ...
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}
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```
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:::
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Examples of **incorrect** TypeScript code for this rule with the `{ "countVoidThis": true }` option:
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:::incorrect
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```ts
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/*eslint max-params: ["error", { "max": 2, "countVoidThis": true }]*/
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function hasNoThis(this: void, first: string, second: string) {
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// ...
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}
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```
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:::

‎lib/rules/max-params.js‎

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@@ -20,6 +20,8 @@ const { upperCaseFirst } = require("../shared/string-utils");
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module.exports = {
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meta: {
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type: "suggestion",
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dialects: ["typescript", "javascript"],
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language: "javascript",
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docs: {
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description:
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type: "integer",
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minimum: 0,
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},
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countVoidThis: {
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type: "boolean",
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description:
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"Whether to count a `this` declaration when the type is `void`.",
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},
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},
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additionalProperties: false,
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},
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const sourceCode = context.sourceCode;
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const option = context.options[0];
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let numParams = 3;
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let countVoidThis = false;
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if (
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typeof option === "object" &&
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(Object.hasOwn(option, "maximum") || Object.hasOwn(option, "max"))
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) {
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numParams = option.maximum || option.max;
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if (typeof option === "object") {
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if (
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Object.hasOwn(option, "maximum") ||
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Object.hasOwn(option, "max")
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) {
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numParams = option.maximum || option.max;
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}
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countVoidThis = option.countVoidThis;
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}
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if (typeof option === "number") {
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numParams = option;
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* @private
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*/
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function checkFunction(node) {
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if (node.params.length > numParams) {
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const hasVoidThisParam =
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node.params.length > 0 &&
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node.params[0].type === "Identifier" &&
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node.params[0].name === "this" &&
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node.params[0].typeAnnotation?.typeAnnotation.type ===
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"TSVoidKeyword";
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const effectiveParamCount =
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hasVoidThisParam && !countVoidThis
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? node.params.length - 1
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: node.params.length;
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if (effectiveParamCount > numParams) {
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context.report({
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loc: astUtils.getFunctionHeadLoc(node, sourceCode),
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node,
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name: upperCaseFirst(
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astUtils.getFunctionNameWithKind(node),
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),
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count: node.params.length,
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count: effectiveParamCount,
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max: numParams,
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},
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});
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FunctionDeclaration: checkFunction,
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ArrowFunctionExpression: checkFunction,
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FunctionExpression: checkFunction,
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TSDeclareFunction: checkFunction,
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TSFunctionType: checkFunction,
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};
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},
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};

‎lib/types/rules.d.ts‎

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@@ -1800,6 +1800,10 @@ export interface ESLintRules extends Linter.RulesRecord {
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* @default 3
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*/
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max: number;
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/**
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* @default false
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*/
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countVoidThis: boolean;
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}>
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| number,
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]

‎tests/lib/rules/max-params.js‎

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@@ -151,3 +151,166 @@ ruleTester.run("max-params", rule, {
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},
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],
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});
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const ruleTesterTypeScript = new RuleTester({
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languageOptions: {
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parser: require("@typescript-eslint/parser"),
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},
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});
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ruleTesterTypeScript.run("max-params", rule, {
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valid: [
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"function foo() {}",
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"const foo = function () {};",
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"const foo = () => {};",
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"function foo(a) {}",
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`
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class Foo {
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constructor(a) {}
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}
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`,
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`
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class Foo {
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method(this: void, a, b, c) {}
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}
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`,
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`
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class Foo {
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method(this: Foo, a, b) {}
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}
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`,
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{
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code: "function foo(a, b, c, d) {}",
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options: [{ max: 4 }],
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},
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{
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code: "function foo(a, b, c, d) {}",
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options: [{ maximum: 4 }],
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},
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{
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code: `
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class Foo {
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method(this: void) {}
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}
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`,
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options: [{ max: 0 }],
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},
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{
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code: `
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class Foo {
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method(this: void, a) {}
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}
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`,
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options: [{ max: 1 }],
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},
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{
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code: `
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class Foo {
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method(this: void, a) {}
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}
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`,
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options: [{ countVoidThis: true, max: 2 }],
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},
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{
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code: `function testD(this: void, a) {}`,
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options: [{ max: 1 }],
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},
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{
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code: `function testD(this: void, a) {}`,
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options: [{ countVoidThis: true, max: 2 }],
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},
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{
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code: `const testE = function (this: void, a) {}`,
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options: [{ max: 1 }],
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},
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{
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code: `const testE = function (this: void, a) {}`,
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options: [{ countVoidThis: true, max: 2 }],
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},
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{
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code: `
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declare function makeDate(m: number, d: number, y: number): Date;
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`,
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options: [{ max: 3 }],
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},
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{
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code: `
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type sum = (a: number, b: number) => number;
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`,
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options: [{ max: 2 }],
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},
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],
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invalid: [
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{
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code: "function foo(a, b, c, d) {}",
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errors: [{ messageId: "exceed" }],
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},
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{
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code: "const foo = function (a, b, c, d) {};",
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errors: [{ messageId: "exceed" }],
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},
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{
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code: "const foo = (a, b, c, d) => {};",
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errors: [{ messageId: "exceed" }],
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},
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{
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code: "const foo = a => {};",
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options: [{ max: 0 }],
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errors: [{ messageId: "exceed" }],
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},
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{
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code: `
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class Foo {
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method(this: void, a, b, c, d) {}
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}
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`,
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errors: [{ messageId: "exceed" }],
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},
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{
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code: `
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class Foo {
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method(this: void, a) {}
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}
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`,
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options: [{ countVoidThis: true, max: 1 }],
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errors: [{ messageId: "exceed" }],
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},
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{
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code: `function testD(this: void, a) {}`,
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options: [{ countVoidThis: true, max: 1 }],
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errors: [{ messageId: "exceed" }],
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},
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{
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code: `const testE = function (this: void, a) {}`,
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options: [{ countVoidThis: true, max: 1 }],
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errors: [{ messageId: "exceed" }],
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},
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{
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code: `function testFunction(test: void, a: number) {}`,
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options: [{ countVoidThis: false, max: 1 }],
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errors: [{ messageId: "exceed" }],
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},
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{
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code: `
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class Foo {
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method(this: Foo, a, b, c) {}
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}
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`,
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errors: [{ messageId: "exceed" }],
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},
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{
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code: `
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declare function makeDate(m: number, d: number, y: number): Date;
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`,
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options: [{ max: 1 }],
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errors: [{ messageId: "exceed" }],
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},
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{
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code: `
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type sum = (a: number, b: number) => number;
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`,
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options: [{ max: 1 }],
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errors: [{ messageId: "exceed" }],
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},
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],
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});

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