8000 feat(eslint-plugin): add option to ignore string const assertiions in… · KuSh/typescript-eslint@9eeaafe · GitHub
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feat(eslint-plugin): add option to ignore string const assertiions in no-unnecessary-type-assertion rule
Fixes typescript-eslint#8721
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‎packages/eslint-plugin/docs/rules/no-unnecessary-type-assertion.mdx

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@@ -73,6 +73,16 @@ function foo(x: number | undefined): number {
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## Options
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### `ignoreStringConstAssertion`
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{/* insert option description */}
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With `@typescript-eslint/no-unnecessary-type-assertion: ["error", { ignoreStringConstAssertion: true }]`, the following is **correct** code:
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```ts option='{ "ignoreStringConstAssertion": true }' showPlaygroundButton
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const foo = `foo` as const;
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```
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### `typesToIgnore`
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{/* insert option description */}

‎packages/eslint-plugin/src/rules/no-unnecessary-type-assertion.ts

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@@ -21,6 +21,7 @@ import {
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export type Options = [
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{
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ignoreStringConstAssertion?: boolean;
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typesToIgnore?: string[];
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},
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];
@@ -48,6 +49,10 @@ export default createRule<Options, MessageIds>({
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type: 'object',
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additionalProperties: false,
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properties: {
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ignoreStringConstAssertion: {
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type: 'boolean',
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description: 'Whether to ignore string const assertions.',
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},
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typesToIgnore: {
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type: 'array',
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description: 'A list of type names to ignore.',
@@ -233,6 +238,14 @@ export default createRule<Options, MessageIds>({
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const uncastType = services.getTypeAtLocation(node.expression);
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const typeIsUnchanged = isTypeUnchanged(uncastType, castType);
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if (
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options.ignoreStringConstAssertion &&
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uncastType.isStringLiteral() &&
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isConstAssertion(node.typeAnnotation)
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) {
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return;
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}
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const wouldSameTypeBeInferred = castType.isLiteral()
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? isImplicitlyNarrowedLiteralDeclaration(node)
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: !isConstAssertion(node.typeAnnotation);

‎packages/eslint-plugin/tests/docs-eslint-output-snapshots/no-unnecessary-type-assertion.shot

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‎packages/eslint-plugin/tests/rules/no-unnecessary-type-assertion.test.ts

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‎packages/eslint-plugin/tests/schema-snapshots/no-unnecessary-type-assertion.shot

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@@ -429,6 +429,18 @@ declare function foo<T extends unknown>(bar: T): T;
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const baz: unknown = {};
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foo(baz!);
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`,
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{
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code: 'const a = `a` as const;',
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options: [{ ignoreStringConstAssertion: true }],
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},
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{
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code: "const a = 'a' as const;",
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options: [{ ignoreStringConstAssertion: true }],
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},
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{
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code: "const a = <const>'a';",
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options: [{ ignoreStringConstAssertion: true }],
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},
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],
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invalid: [