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fix(eslint-plugin): [no-unnecessary-condition] improve checking optional callee #8178

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merged 1 commit into from
Jan 8, 2024
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fix(eslint-plugin): [no-unnecessary-condition] improve checking optional callee #8178

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29 changes: 26 additions & 3 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 @@ -547,7 +547,7 @@ export default createRule<Options, MessageId>({
// declare const foo: { bar : { baz: string } } | null
// foo?.bar;
// ```
function isNullableOriginFromPrev(
function isMemberExpressionNullableOriginFromObject(
node: TSESTree.MemberExpression,
): boolean {
const prevType = getConstrainedTypeAtLocation(services, node.object);
Expand Down Expand Up @@ -580,12 +580,35 @@ export default createRule<Options, MessageId>({
return false;
}

function isCallExpressionNullableOriginFromCallee(
node: TSESTree.CallExpression,
): boolean {
const prevType = getConstrainedTypeAtLocation(services, node.callee);

if (prevType.isUnion()) {
const isOwnNullable = prevType.types.some(type => {
const signatures = type.getCallSignatures();
return signatures.some(sig =>
isNullableType(sig.getReturnType(), { allowUndefined: true }),
);
});
return (
!isOwnNullable && isNullableType(prevType, { allowUndefined: true })
);
}

return false;
}

function isOptionableExpression(node: TSESTree.Expression): boolean {
const type = getConstrainedTypeAtLocation(services, node);
const isOwnNullable =
node.type === AST_NODE_TYPES.MemberExpression
? !isNullableOriginFromPrev(node)
: true;
? !isMemberExpressionNullableOriginFromObject(node)
: node.type === AST_NODE_TYPES.CallExpression
? !isCallExpressionNullableOriginFromCallee(node)
: true;

const possiblyVoid = isTypeFlagSet(type, ts.TypeFlags.Void);
return (
isTypeFlagSet(type, ts.TypeFlags.Any | ts.TypeFlags.Unknown) ||
Expand Down
134 changes: 134 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 @@ -774,6 +774,28 @@ function getElem(dict: Record<string, { foo: string }>, key: string) {
typescript: '4.1',
},
},
`
type Foo = { bar: () => number | undefined } | null;
declare const foo: Foo;
foo?.bar()?.toExponential();
`,
`
type Foo = (() => number | undefined) | null;
declare const foo: Foo;
foo?.()?.toExponential();
`,
`
type FooUndef = () => undefined;
type FooNum = () => number;
type Foo = FooUndef | FooNum | null;
declare const foo: Foo;
foo?.()?.toExponential();
`,
`
type Foo = { [key: string]: () => number | undefined } | null;
declare const foo: Foo;
foo?.['bar']()?.toExponential();
`,
],
invalid: [
// Ensure that it's checking in all the right places
Expand Down Expand Up @@ -1993,6 +2015,118 @@ foo &&= null;
},
],
},
{
code: noFormat`
type Foo = { bar: () => number } | null;
declare const foo: Foo;
foo?.bar()?.toExponential();
`,
output: noFormat`
type Foo = { bar: () => number } | null;
declare const foo: Foo;
foo?.bar().toExponential();
`,
errors: [
{
messageId: 'neverOptionalChain',
line: 4,
column: 11,
endLine: 4,
endColumn: 13,
},
],
},
{
code: noFormat`
type Foo = { bar: null | { baz: () => { qux: number } } } | null;
declare const foo: Foo;
foo?.bar?.baz()?.qux?.toExponential();
`,
output: noFormat`
type Foo = { bar: null | { baz: () => { qux: number } } } | null;
declare const foo: Foo;
foo?.bar?.baz().qux.toExponential();
`,
errors: [
{
messageId: 'neverOptionalChain',
line: 4,
column: 16,
endLine: 4,
endColumn: 18,
},
{
messageId: 'neverOptionalChain',
line: 4,
column: 21,
endLine: 4,
endColumn: 23,
},
],
},
{
code: noFormat`
type Foo = (() => number) | null;
declare const foo: Foo;
foo?.()?.toExponential();
`,
output: noFormat`
type Foo = (() => number) | null;
declare const foo: Foo;
foo?.().toExponential();
`,
errors: [
{
messageId: 'neverOptionalChain',
line: 4,
column: 8,
endLine: 4,
endColumn: 10,
},
],
},
{
code: noFormat`
type Foo = { [key: string]: () => number } | null;
declare const foo: Foo;
foo?.['bar']()?.toExponential();
`,
output: noFormat`
type Foo = { [key: string]: () => number } | null;
declare const foo: Foo;
foo?.['bar']().toExponential();
`,
errors: [
{
messageId: 'neverOptionalChain',
line: 4,
column: 15,
endLine: 4,
endColumn: 17,
},
],
},
{
code: noFormat`
type Foo = { [key: string]: () => number } | null;
declare const foo: Foo;
foo?.['bar']?.()?.toExponential();
`,
output: noFormat`
type Foo = { [key: string]: () => number } | null;
declare const foo: Foo;
foo?.['bar']?.().toExponential();
`,
errors: [
{
messageId: 'neverOptionalChain',
line: 4,
column: 17,
endLine: 4,
endColumn: 19,
},
],
},

// "branded" types
unnecessaryConditionTest('"" & {}', 'alwaysFalsy'),
Expand Down