Skip to content

fix(eslint-plugin): [prefer-find] support ternary branches in prefer-find #8421

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 7 commits into from
Mar 11, 2024
Merged

fix(eslint-plugin): [prefer-find] support ternary branches in prefer-find #8421

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
7 commits
Select commit Hold shift + click to select a range
f372aba
8379: Support ternary branches in prefer-find
kirkwaiblinger Feb 5, 2024
0db4183
fix codecov
kirkwaiblinger Feb 9, 2024
2200f83
lintfix
kirkwaiblinger Feb 9, 2024
7fd8285
Update packages/eslint-plugin/tests/rules/prefer-find.test.ts
kirkwaiblinger Feb 23, 2024
9d1b79a
add some straightforward tests
kirkwaiblinger Feb 23, 2024
f397a3a
remove any
kirkwaiblinger Feb 24, 2024
9e599c0
tweak tests slightly
kirkwaiblinger Feb 24, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
66 changes: 47 additions & 19 deletions packages/eslint-plugin/src/rules/prefer-find.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -41,20 +41,41 @@ export default createRule({
filterNode: TSESTree.Node;
}

function parseIfArrayFilterExpression(
function parseArrayFilterExpressions(
expression: TSESTree.Expression,
): FilterExpressionData | undefined {
): FilterExpressionData[] {
if (expression.type === AST_NODE_TYPES.SequenceExpression) {
// Only the last expression in (a, b, [1, 2, 3].filter(condition))[0] matters
const lastExpression = nullThrows(
expression.expressions.at(-1),
'Expected to have more than zero expressions in a sequence expression',
);
return parseIfArrayFilterExpression(lastExpression);
return parseArrayFilterExpressions(lastExpression);
}

if (expression.type === AST_NODE_TYPES.ChainExpression) {
return parseIfArrayFilterExpression(expression.expression);
return parseArrayFilterExpressions(expression.expression);
}

// This is the only reason we're returning a list rather than a single value.
if (expression.type === AST_NODE_TYPES.ConditionalExpression) {
// Both branches of the ternary _must_ return results.
const consequentResult = parseArrayFilterExpressions(
expression.consequent,
);
if (consequentResult.length === 0) {
return [];
}

const alternateResult = parseArrayFilterExpressions(
expression.alternate,
);
if (alternateResult.length === 0) {
return [];
}

// Accumulate the results from both sides and pass up the chain.
return [...consequentResult, ...alternateResult];
}

// Check if it looks like <<stuff>>(...), but not <<stuff>>?.(...)
Expand All @@ -78,16 +99,19 @@ export default createRule({
// As long as the object is a (possibly nullable) array,
// this is an Array.prototype.filter expression.
if (isArrayish(filteredObjectType)) {
return {
isBracketSyntaxForFilter,
filterNode,
};
return [
{
isBracketSyntaxForFilter,
filterNode,
},
];
}
}
}
}

return undefined;
// not a filter expression.
return [];
}

/**
Expand Down Expand Up @@ -223,8 +247,8 @@ export default createRule({
CallExpression(node): void {
const object = getObjectIfArrayAtZeroExpression(node);
if (object) {
const filterExpression = parseIfArrayFilterExpression(object);
if (filterExpression) {
const filterExpressions = parseArrayFilterExpressions(object);
if (filterExpressions.length !== 0) {
context.report({
node,
messageId: 'preferFind',
Expand All @@ -233,9 +257,11 @@ export default createRule({
messageId: 'preferFindSuggestion',
fix: (fixer): TSESLint.RuleFix[] => {
return [
generateFixToReplaceFilterWithFind(
fixer,
filterExpression,
...filterExpressions.map(filterExpression =>
generateFixToReplaceFilterWithFind(
fixer,
filterExpression,
),
),
// Get rid of the .at(0) or ['at'](0).
generateFixToRemoveArrayElementAccess(
Expand All @@ -261,8 +287,8 @@ export default createRule({
): void {
if (isMemberAccessOfZero(node)) {
const object = node.object;
const filterExpression = parseIfArrayFilterExpression(object);
if (filterExpression) {
const filterExpressions = parseArrayFilterExpressions(object);
if (filterExpressions.length !== 0) {
context.report({
node,
messageId: 'preferFind',
Expand All @@ -271,9 +297,11 @@ export default createRule({
messageId: 'preferFindSuggestion',
fix: (fixer): TSESLint.RuleFix[] => {
return [
generateFixToReplaceFilterWithFind(
fixer,
filterExpression,
...filterExpressions.map(filterExpression =>
generateFixToReplaceFilterWithFind(
fixer,
filterExpression,
),
),
// Get rid of the [0].
generateFixToRemoveArrayElementAccess(
Expand Down
143 changes: 143 additions & 0 deletions packages/eslint-plugin/tests/rules/prefer-find.test.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -70,6 +70,12 @@ ruleTester.run('prefer-find', rule, {
`,
"[1, 2, 3].filter(x => x)[Symbol('0')];",
"[1, 2, 3].filter(x => x)[Symbol.for('0')];",
'(Math.random() < 0.5 ? [1, 2, 3].filter(x => true) : [1, 2, 3])[0];',
`
(Math.random() < 0.5
? [1, 2, 3].find(x => true)
: [1, 2, 3].filter(x => true))[0];
`,
],

invalid: [
Expand Down Expand Up @@ -584,5 +590,142 @@ arr.find(f, thisArg);
},
],
},
{
Copy link
Member

@JoshuaKGoldberg JoshuaKGoldberg Feb 23, 2024 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

[Testing] Just to be through, could you also add a test for a desired report with and within a ternary? Like the valid case above, but either with two .filters or with the [0] on the other side of the last )?

(Math.random() < 0.5
  ? [1, 2, 3].filter(x => false)
  : [1, 2, 3].filter(x => true))[0];
(Math.random() < 0.5
  ? [1, 2, 3].find(x => true)
  : [1, 2, 3].filter(x => true)[0]);

The cases lower down are a bit more complex. It's nice to have more straightforward ones to use as a reference too.

code: `
(Math.random() < 0.5
? [1, 2, 3].filter(x => false)
: [1, 2, 3].filter(x => true))[0];
`,
errors: [
{
line: 2,
messageId: 'preferFind',
suggestions: [
{
messageId: 'preferFindSuggestion',
output: `
(Math.random() < 0.5
? [1, 2, 3].find(x => false)
: [1, 2, 3].find(x => true));
`,
},
],
},
],
},
{
code: `
Math.random() < 0.5
? [1, 2, 3].find(x => true)
: [1, 2, 3].filter(x => true)[0];
`,
errors: [
{
line: 4,
messageId: 'preferFind',
suggestions: [
{
messageId: 'preferFindSuggestion',
output: `
Math.random() < 0.5
? [1, 2, 3].find(x => true)
: [1, 2, 3].find(x => true);
`,
},
],
},
],
},
{
code: `
declare const f: (arg0: unknown, arg1: number, arg2: Array<unknown>) => boolean,
g: (arg0: unknown) => boolean;
const nestedTernaries = (
Math.random() < 0.5
? Math.random() < 0.5
? [1, 2, 3].filter(f)
: []?.filter(x => 'shrug')
: [2, 3, 4]['filter'](g)
).at(0.2);
`,
errors: [
{
line: 4,
messageId: 'preferFind',
suggestions: [
{
messageId: 'preferFindSuggestion',
output: `
declare const f: (arg0: unknown, arg1: number, arg2: Array<unknown>) => boolean,
g: (arg0: unknown) => boolean;
const nestedTernaries = (
Math.random() < 0.5
? Math.random() < 0.5
? [1, 2, 3].find(f)
: []?.find(x => 'shrug')
: [2, 3, 4]["find"](g)
);
`,
},
],
},
],
},

{
code: `
declare const f: (arg0: unknown) => boolean, g: (arg0: unknown) => boolean;
const nestedTernariesWithSequenceExpression = (
Math.random() < 0.5
? ('sequence',
'expression',
Math.random() < 0.5 ? [1, 2, 3].filter(f) : []?.filter(x => 'shrug'))
: [2, 3, 4]['filter'](g)
).at(0.2);
`,
errors: [
{
line: 3,
messageId: 'preferFind',
suggestions: [
{
messageId: 'preferFindSuggestion',
output: `
declare const f: (arg0: unknown) => boolean, g: (arg0: unknown) => boolean;
const nestedTernariesWithSequenceExpression = (
Math.random() < 0.5
? ('sequence',
'expression',
Math.random() < 0.5 ? [1, 2, 3].find(f) : []?.find(x => 'shrug'))
: [2, 3, 4]["find"](g)
);
`,
},
],
},
],
},

{
code: `
declare const spreadArgs: [(x: unknown) => boolean];
[1, 2, 3].filter(...spreadArgs).at(0);
`,
errors: [
{
line: 3,
messageId: 'preferFind',
suggestions: [
{
messageId: 'preferFindSuggestion',
output: `
declare const spreadArgs: [(x: unknown) => boolean];
[1, 2, 3].find(...spreadArgs);
`,
},
],
},
],
},
],
});