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fix(eslint-plugin): [no-unnecessary-condition] fix false positive when checking indexed access types #6452

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Merged
merged 3 commits into from
Feb 13, 2023
Merged

fix(eslint-plugin): [no-unnecessary-condition] fix false positive when checking indexed access types #6452

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ad9ec4b
add new tests
uhyo Feb 11, 2023
e8a80b7
allow naked index access type to be a condition
uhyo Feb 11, 2023
c91737f
Merge branch 'main' into fix-6264
uhyo Feb 12, 2023
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4 changes: 2 additions & 2 deletions packages/eslint-plugin/src/rules/no-unnecessary-condition.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -235,13 +235,13 @@ export default createRule<Options, MessageId>({
const type = getNodeType(node);

// Conditional is always necessary if it involves:
// `any` or `unknown` or a naked type parameter
// `any` or `unknown` or a naked type variable
if (
unionTypeParts(type).some(
part =>
isTypeAnyType(part) ||
isTypeUnknownType(part) ||
isTypeFlagSet(part, ts.TypeFlags.TypeParameter),
isTypeFlagSet(part, ts.TypeFlags.TypeVariable),
)
) {
return;
Expand Down
75 changes: 75 additions & 0 deletions packages/eslint-plugin/tests/rules/no-unnecessary-condition.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -549,6 +549,36 @@ type OptionalFoo = Foo | undefined;
declare const foo: OptionalFoo;
foo?.[1]?.length;
`,
// https://github.com/typescript-eslint/typescript-eslint/issues/6264
`
function get<Obj, Key extends keyof Obj>(obj: Obj, key: Key) {
const value = obj[key];
if (value) {
return value;
}
throw new Error('BOOM!');
}

get({ foo: null }, 'foo');
`,
{
code: `
function getElem(dict: Record<string, { foo: string }>, key: string) {
if (dict[key]) {
return dict[key].foo;
} else {
return '';
}
}
`,
parserOptions: {
tsconfigRootDir: getFixturesRootDir(),
project: './tsconfig.noUncheckedIndexedAccess.json',
},
dependencyConstraints: {
typescript: '4.1',
},
},
],
invalid: [
// Ensure that it's checking in all the right places
Expand Down Expand Up @@ -1601,5 +1631,50 @@ foo?.test.length;
},
],
},
{
code: `
function pick<Obj extends Record<string, 1 | 2 | 3>, Key extends keyof Obj>(
obj: Obj,
key: Key,
): Obj[Key] {
const k = obj[key];
if (obj[key]) {
return obj[key];
}
throw new Error('Boom!');
}

pick({ foo: 1, bar: 2 }, 'bar');
`,
errors: [
{
messageId: 'alwaysTruthy',
line: 7,
endLine: 7,
column: 7,
endColumn: 15,
},
],
},
{
code: `
function getElem(dict: Record<string, { foo: string }>, key: string) {
if (dict[key]) {
return dict[key].foo;
} else {
return '';
}
}
`,
errors: [
{
messageId: 'alwaysTruthy',
line: 3,
endLine: 3,
column: 7,
endColumn: 16,
},
],
},
],
});