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chore(eslint-plugin): switch auto-generated test cases to hand-written in no-base-to-string.test.ts #11273

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chore(eslint-plugin): switch auto-generated test cases to hand-written in no-base-to-string.test.ts #11273

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304 changes: 267 additions & 37 deletions packages/eslint-plugin/tests/rules/no-base-to-string.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -13,55 +13,285 @@ const ruleTester = new RuleTester({
},
});

const literalListBasic: string[] = [
"''",
"'text'",
'true',
'false',
'1',
'1n',
'[]',
'/regex/',
];

const literalListNeedParen: string[] = [
"__dirname === 'foobar'",
'{}.constructor()',
'() => {}',
'function() {}',
];

const literalList = [...literalListBasic, ...literalListNeedParen];

const literalListWrapped = [
...literalListBasic,
...literalListNeedParen.map(i => `(${i})`),
];
/**
* ref: https://github.com/typescript-eslint/typescript-eslint/issues/11043
* Be careful with dynamic test case generation.
* Iterate based on the following cases:
* 1. literalListBasic
* ```
[
"''",
"'text'",
'true',
'false',
'1',
'1n',
'[]',
'/regex/',
];
* ```
* 2. literalListNeedParen
* ```
[
"__dirname === 'foobar'",
'{}.constructor()',
'() => {}',
'function() {}',
];
* ```
*/

ruleTester.run('no-base-to-string', rule, {
valid: [
// template
...literalList.map(i => `\`\${${i}}\`;`),
"`${''}`;",
"`${'text'}`;",
'`${true}`;',
'`${false}`;',
'`${1}`;',
'`${1n}`;',
'`${[]}`;',
'`${/regex/}`;',
"`${__dirname === 'foobar'}`;",
'`${{}.constructor()}`;',
'`${() => {}}`;',
'`${function () {}}`;',

// operator + +=
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@nayounsang nayounsang Jun 5, 2025 •
edited
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Many of the test cases in the operator + section are essentially duplicates that only differ in operand order. We could consider reducing them by half.
related to this comment: #11273 (comment)

...literalListWrapped.flatMap(l =>
literalListWrapped.map(r => `${l} + ${r};`),
),
"'' + '';",
"'' + 'text';",
"'' + true;",
"'' + false;",
"'' + 1;",
"'' + 1n;",
"'' + [];",
"'' + /regex/;",
"'' + (__dirname === 'foobar');",
"'' + {}.constructor();",
"'' + (() => {});",
"'' + function () {};",
"'text' + '';",
"'text' + 'text';",
"'text' + true;",
"'text' + false;",
"'text' + 1;",
"'text' + 1n;",
"'text' + [];",
"'text' + /regex/;",
"'text' + (__dirname === 'foobar');",
"'text' + {}.constructor();",
"'text' + (() => {});",
"'text' + function () {};",
"true + '';",
"true + 'text';",
'true + true;',
'true + false;',
'true + 1;',
'true + 1n;',
'true + [];',
'true + /regex/;',
"true + (__dirname === 'foobar');",
'true + {}.constructor();',
'true + (() => {});',
'true + function () {};',
"false + '';",
"false + 'text';",
'false + true;',
'false + false;',
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'false + true;',
'false + false;',
'true + true;',
'true + false;',

In my opinion, it would be neater to leave only one of these.

'false + 1;',
'false + 1n;',
'false + [];',
'false + /regex/;',
"false + (__dirname === 'foobar');",
'false + {}.constructor();',
'false + (() => {});',
'false + function () {};',
"1 + '';",
"1 + 'text';",
'1 + true;',
'1 + false;',
'1 + 1;',
'1 + 1n;',
'1 + [];',
'1 + /regex/;',
"1 + (__dirname === 'foobar');",
'1 + {}.constructor();',
'1 + (() => {});',
'1 + function () {};',
"1n + '';",
"1n + 'text';",
'1n + true;',
'1n + false;',
'1n + 1;',
'1n + 1n;',
'1n + [];',
'1n + /regex/;',
"1n + (__dirname === 'foobar');",
'1n + {}.constructor();',
'1n + (() => {});',
'1n + function () {};',
"[] + '';",
"[] + 'text';",
'[] + true;',
'[] + false;',
'[] + 1;',
'[] + 1n;',
'[] + [];',
'[] + /regex/;',
"[] + (__dirname === 'foobar');",
'[] + {}.constructor();',
'[] + (() => {});',
'[] + function () {};',
"/regex/ + '';",
"/regex/ + 'text';",
'/regex/ + true;',
'/regex/ + false;',
'/regex/ + 1;',
'/regex/ + 1n;',
'/regex/ + [];',
'/regex/ + /regex/;',
"/regex/ + (__dirname === 'foobar');",
'/regex/ + {}.constructor();',
'/regex/ + (() => {});',
'/regex/ + function () {};',
"(__dirname === 'foobar') + '';",
"(__dirname === 'foobar') + 'text';",
"(__dirname === 'foobar') + true;",
"(__dirname === 'foobar') + false;",
"(__dirname === 'foobar') + 1;",
"(__dirname === 'foobar') + 1n;",
"(__dirname === 'foobar') + [];",
"(__dirname === 'foobar') + /regex/;",
"(__dirname === 'foobar') + (__dirname === 'foobar');",
"(__dirname === 'foobar') + {}.constructor();",
"(__dirname === 'foobar') + (() => {});",
"(__dirname === 'foobar') + function () {};",
"({}).constructor() + '';",
"({}).constructor() + 'text';",
'({}).constructor() + true;',
'({}).constructor() + false;',
'({}).constructor() + 1;',
'({}).constructor() + 1n;',
'({}).constructor() + [];',
'({}).constructor() + /regex/;',
"({}).constructor() + (__dirname === 'foobar');",
'({}).constructor() + {}.constructor();',
'({}).constructor() + (() => {});',
'({}).constructor() + function () {};',
"(() => {}) + '';",
"(() => {}) + 'text';",
'(() => {}) + true;',
'(() => {}) + false;',
'(() => {}) + 1;',
'(() => {}) + 1n;',
'(() => {}) + [];',
'(() => {}) + /regex/;',
"(() => {}) + (__dirname === 'foobar');",
'(() => {}) + {}.constructor();',
'(() => {}) + (() => {});',
'(() => {}) + function () {};',
"(function () {}) + '';",
"(function () {}) + 'text';",
'(function () {}) + true;',
'(function () {}) + false;',
'(function () {}) + 1;',
'(function () {}) + 1n;',
'(function () {}) + [];',
'(function () {}) + /regex/;',
"(function () {}) + (__dirname === 'foobar');",
'(function () {}) + {}.constructor();',
'(function () {}) + (() => {});',
'(function () {}) + function () {};',

// toString()
...literalListWrapped.map(i => `${i === '1' ? `(${i})` : i}.toString();`),
"''.toString();",
"'text'.toString();",
'true.toString();',
'false.toString();',
'(1).toString();',
'1n.toString();',
'[].toString();',
'/regex/.toString();',
"(__dirname === 'foobar').toString();",
'({}).constructor().toString();',
'(() => {}).toString();',
'(function () {}).toString();',

// variable toString() and template
...literalList.map(
i => `
let value = ${i};
value.toString();
let text = \`\${value}\`;
`,
),
`
let value = '';
value.toString();
let text = \`\${value}\`;
`,
`
let value = 'text';
value.toString();
let text = \`\${value}\`;
`,
`
let value = true;
value.toString();
let text = \`\${value}\`;
`,
`
let value = false;
value.toString();
let text = \`\${value}\`;
`,
`
let value = 1;
value.toString();
let text = \`\${value}\`;
`,
`
let value = 1n;
value.toString();
let text = \`\${value}\`;
`,
`
let value = [];
value.toString();
let text = \`\${value}\`;
`,
`
let value = /regex/;
value.toString();
let text = \`\${value}\`;
`,
`
let value = __dirname === 'foobar';
value.toString();
let text = \`\${value}\`;
`,
`
let value = {}.constructor();
value.toString();
let text = \`\${value}\`;
`,
`
let value = () => {};
value.toString();
let text = \`\${value}\`;
`,
`
let value = function () {};
value.toString();
let text = \`\${value}\`;
`,

// String()
...literalList.map(i => `String(${i});`),
"String('');",
"String('text');",
'String(true);',
'String(false);',
'String(1);',
'String(1n);',
'String([]);',
'String(/regex/);',
"String(__dirname === 'foobar');",
'String({}.constructor());',
'String(() => {});',
'String(function () {});',
`
function someFunction() {}
someFunction.toString();
Expand Down