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no-useless-undefined: Ignore undefined use in compare functions #758

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merged 3 commits into from Jun 1, 2020
Merged

no-useless-undefined: Ignore undefined use in compare functions #758

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a2c457a
`no-useless-undefined`: Ignore `undefined` use in compare functions
fisker Jun 1, 2020
e18b633
Fix `===`
fisker Jun 1, 2020
6535e59
Style
fisker Jun 1, 2020
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41 changes: 41 additions & 0 deletions rules/no-useless-undefined.js
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Expand Up @@ -32,6 +32,43 @@ const assignmentPatternSelector = getSelector('AssignmentPattern', 'right');

const isUndefined = node => node && node.type === 'Identifier' && node.name === 'undefined';

const compareFunctionNames = new Set([
'is',
'equal',
'notEqual',
'strictEqual',
'notStrictEqual',
'propertyVal',
'notPropertyVal',
'not',
'include',
'property',
'toBe',
'toContain',
'toContainEqual',
'toEqual',
'same',
'notSame',
'strictSame',
'strictNotSame'
]);
const isCompareFunction = node => {
let name;

if (node.type === 'Identifier') {
name = node.name;
} else if (
node.type === 'MemberExpression' &&
node.computed === false &&
node.property &&
node.property.type === 'Identifier'
) {
name = node.property.name;
}

return compareFunctionNames.has(name);
};

const create = context => {
const listener = fix => node => {
context.report({
Expand Down Expand Up @@ -64,6 +101,10 @@ const create = context => {
(node, fixer) => fixer.removeRange([node.parent.left.range[1], node.range[1]])
),
CallExpression: node => {
if (isCompareFunction(node.callee)) {
return;
}

const argumentNodes = node.arguments;
const undefinedArguments = [];
for (let index = argumentNodes.length - 1; index >= 0; index--) {
Expand Down
23 changes: 22 additions & 1 deletion test/no-useless-undefined.js
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Expand Up @@ -31,7 +31,28 @@ ruleTester.run('no-useless-undefined', rule, {
'function foo({bar} = {}) {}',
'function foo(bar) {}',
// I guess nobody use this, but `yield* undefined;` is valid code, and `yield*;` is not
'function* foo() {yield* undefined;}'
'function* foo() {yield* undefined;}',

// Ignored
'if (Object.is(foo, undefined)){}',
't.is(foo, undefined)',
'assert.equal(foo, undefined, message)',
'assert.notEqual(foo, undefined, message)',
'assert.strictEqual(foo, undefined, message)',
'assert.notStrictEqual(foo, undefined, message)',
'assert.propertyVal(foo, "bar", undefined, message)',
'assert.notPropertyVal(foo, "bar", undefined, message)',
'expect(foo).not(undefined)',
'expect(foo).to.have.property("bar", undefined)',
'expect(foo).to.have.property("bar", undefined)',
'expect(foo).toBe(undefined)',
'expect(foo).toContain(undefined)',
'expect(foo).toContainEqual(undefined)',
'expect(foo).toEqual(undefined)',
't.same(foo, undefined)',
't.notSame(foo, undefined)',
't.strictSame(foo, undefined)',
't.strictNotSame(foo, undefined)'
],
invalid: [
{
Expand Down