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fix(eslint-plugin): [no-unsafe-enum-comparison] add logic to see through intersections #9777

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Merged
merged 4 commits into from
Aug 19, 2024
Merged

fix(eslint-plugin): [no-unsafe-enum-comparison] add logic to see through intersections #9777

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4e67576
fix: bug with intersections in no-unsafe-enum-comparison
Zamiell Aug 11, 2024
65e3a98
refactor: remove failing test case
Zamiell Aug 11, 2024
1445963
Merge branch 'main' into fix-7114
Zamiell Aug 11, 2024
fa0edf3
feat: add more test cases
Zamiell Aug 12, 2024
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45 changes: 33 additions & 12 deletions packages/eslint-plugin/src/rules/no-unsafe-enum-comparison.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -12,23 +12,37 @@ import {
/**
* @returns Whether the right type is an unsafe comparison against any left type.
*/
function typeViolates(leftTypeParts: ts.Type[], right: ts.Type): boolean {
const leftValueKinds = new Set(leftTypeParts.map(getEnumValueType));
function typeViolates(leftTypeParts: ts.Type[], rightType: ts.Type): boolean {
const leftEnumValueTypes = new Set(leftTypeParts.map(getEnumValueType));

return (
(leftValueKinds.has(ts.TypeFlags.Number) &&
tsutils.isTypeFlagSet(
right,
ts.TypeFlags.Number | ts.TypeFlags.NumberLike,
)) ||
(leftValueKinds.has(ts.TypeFlags.String) &&
tsutils.isTypeFlagSet(
right,
ts.TypeFlags.String | ts.TypeFlags.StringLike,
))
(leftEnumValueTypes.has(ts.TypeFlags.Number) && isNumberLike(rightType)) ||
(leftEnumValueTypes.has(ts.TypeFlags.String) && isStringLike(rightType))
);
}

function isNumberLike(type: ts.Type): boolean {
const typeParts = tsutils.intersectionTypeParts(type);

return typeParts.some(typePart => {
return tsutils.isTypeFlagSet(
typePart,
ts.TypeFlags.Number | ts.TypeFlags.NumberLike,
);
});
}

function isStringLike(type: ts.Type): boolean {
const typeParts = tsutils.intersectionTypeParts(type);

return typeParts.some(typePart => {
return tsutils.isTypeFlagSet(
typePart,
ts.TypeFlags.String | ts.TypeFlags.StringLike,
);
});
}

/**
* @returns What type a type's enum value is (number or string), if either.
*/
Expand Down Expand Up @@ -90,6 +104,13 @@ export default createRule({
}
}

// We need to split the type into the union type parts in order to find
// valid enum comparisons like:
//
// ```ts
// declare const something: Fruit | Vegetable;
// something === Fruit.Apple;
// ```
const leftTypeParts = tsutils.unionTypeParts(leftType);
const rightTypeParts = tsutils.unionTypeParts(rightType);

Expand Down
54 changes: 44 additions & 10 deletions packages/eslint-plugin/tests/rules/no-unsafe-enum-comparison.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -221,16 +221,6 @@ ruleTester.run('no-unsafe-enum-comparison', rule, {
declare const right: string | Vegetable2;
left === right;
`,
`
enum Vegetable {
Asparagus = 'asparagus',
Beet = 'beet',
Celery = 'celery',
}
type WeirdString = string & { __someBrand: void };
declare const weirdString: WeirdString;
Vegetable.Asparagus === weirdString;
`,
`
enum Vegetable {
Asparagus = 'asparagus',
Expand Down Expand Up @@ -1212,5 +1202,49 @@ ruleTester.run('no-unsafe-enum-comparison', rule, {
},
],
},
{
code: `
enum Fruit {
Apple,
}
declare const foo: number & {};
if (foo === Fruit.Apple) {
}
`,
errors: [{ messageId: 'mismatchedCondition' }],
},
{
code: `
enum Fruit {
Apple,
}
declare const foo: number & { __someBrand: void };
if (foo === Fruit.Apple) {
}
`,
errors: [{ messageId: 'mismatchedCondition' }],
},
{
code: `
enum Vegetable {
Asparagus = 'asparagus',
}
declare const foo: string & {};
if (foo === Vegetable.Asparagus) {
}
`,
errors: [{ messageId: 'mismatchedCondition' }],
},
{
code: `
enum Vegetable {
Asparagus = 'asparagus',
}
declare const foo: string & { __someBrand: void };
if (foo === Vegetable.Asparagus) {
}
`,
errors: [{ messageId: 'mismatchedCondition' }],
},
],
});
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