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feat(linter): implement unicorn/no-negation-in-equality-check (#4034)

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Fixes https://github.com/oxc-project/oxc/issues/3869

Hey there, thought I'd give this a try as it's tagged "good first issue"
:) Let me know if there's anything that needs to change, I wasn't sure
about the rule category so left as TODO.
This commit is contained in:
Nissim Chekroun 2024-07-04 16:05:47 +01:00 committed by GitHub
parent 38e7351a91
commit bf04dee861
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3 changed files with 230 additions and 0 deletions
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2
crates/oxc_linter/src/rules.rs
View file

@ -260,6 +260,7 @@ mod unicorn {
pub mod no_lonely_if;
pub mod no_magic_array_flat_depth;
pub mod no_negated_condition;
pub mod no_negation_in_equality_check;
pub mod no_nested_ternary;
pub mod no_new_array;
pub mod no_new_buffer;
@ -619,6 +620,7 @@ oxc_macros::declare_all_lint_rules! {
unicorn::no_lonely_if,
unicorn::no_magic_array_flat_depth,
unicorn::no_negated_condition,
unicorn::no_negation_in_equality_check,
unicorn::no_nested_ternary,
unicorn::no_new_array,
unicorn::no_new_buffer,

135
crates/oxc_linter/src/rules/unicorn/no_negation_in_equality_check.rs Normal file
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@ -0,0 +1,135 @@
use oxc_ast::{ast::Expression, AstKind};
use oxc_diagnostics::OxcDiagnostic;
use oxc_macros::declare_oxc_lint;
use oxc_span::Span;
use oxc_syntax::operator::{BinaryOperator, UnaryOperator};
use crate::{context::LintContext, rule::Rule, AstNode};
fn no_negation_in_equality_check_diagnostic(
span0: Span,
current_operator: BinaryOperator,
suggested_operator: BinaryOperator,
) -> OxcDiagnostic {
OxcDiagnostic::warn(
"eslint-plugin-unicorn(no-negation-in-equality-check): Negated expression is not allowed in equality check.",
)
.with_help(format!("Remove the negation operator and use '{}' instead of '{}'.", suggested_operator.as_str(), current_operator.as_str()))
.with_label(span0)
}
#[derive(Debug, Default, Clone)]
pub struct NoNegationInEqualityCheck;
declare_oxc_lint!(
/// ### What it does
///
/// Disallow negated expressions on the left of (in)equality checks.
///
/// ### Why is this bad?
///
/// A negated expression on the left of an (in)equality check is likely a mistake from trying to negate the whole condition.
///
/// ### Example
/// ```javascript
/// // Bad
///
/// if (!foo === bar) {}
///
/// if (!foo !== bar) {}
///
/// // Good
///
/// if (foo !== bar) {}
///
/// if (!(foo === bar)) {}
/// ```
NoNegationInEqualityCheck,
correctness,
);
impl Rule for NoNegationInEqualityCheck {
fn run<'a>(&self, node: &AstNode<'a>, ctx: &LintContext<'a>) {
if let AstKind::BinaryExpression(binary_expr) = node.kind() {
let Expression::UnaryExpression(left_unary_expr) = &binary_expr.left else {
return;
};
if left_unary_expr.operator != UnaryOperator::LogicalNot {
return;
}
if let Expression::UnaryExpression(left_nested_unary_expr) = &left_unary_expr.argument {
if left_nested_unary_expr.operator == UnaryOperator::LogicalNot {
return;
}
}
if !binary_expr.operator.is_equality() {
return;
}
let Some(suggested_operator) = binary_expr.operator.equality_inverse_operator() else {
return;
};
ctx.diagnostic(no_negation_in_equality_check_diagnostic(
left_unary_expr.span,
binary_expr.operator,
suggested_operator,
));
}
}
}
#[test]
fn test() {
use crate::tester::Tester;
let pass = vec![
"!foo instanceof bar",
"+foo === bar",
"!(foo === bar)",
"!!foo === bar",
"!!!foo === bar",
"foo === !bar",
];
let fail = vec![
"!foo === bar",
"!foo !== bar",
"!foo == bar",
"!foo != bar",
"
function x() {
return!foo === bar;
}
",
"
function x() {
return!
foo === bar;
throw!
foo === bar;
}
",
"
foo
!(a) === b
",
"
foo
![a, b].join('') === c
",
"
foo
! [a, b].join('') === c
",
"
foo
!/* comment */[a, b].join('') === c
",
];
Tester::new(NoNegationInEqualityCheck::NAME, pass, fail).test_and_snapshot();
}

93
crates/oxc_linter/src/snapshots/no_negation_in_equality_check.snap Normal file
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@ -0,0 +1,93 @@
---
source: crates/oxc_linter/src/tester.rs
---
⚠ eslint-plugin-unicorn(no-negation-in-equality-check): Negated expression is not allowed in equality check.
╭─[no_negation_in_equality_check.tsx:1:1]
1 │ !foo === bar
· ────
╰────
help: Remove the negation operator and use '!==' instead of '==='.
⚠ eslint-plugin-unicorn(no-negation-in-equality-check): Negated expression is not allowed in equality check.
╭─[no_negation_in_equality_check.tsx:1:1]
1 │ !foo !== bar
· ────
╰────
help: Remove the negation operator and use '===' instead of '!=='.
⚠ eslint-plugin-unicorn(no-negation-in-equality-check): Negated expression is not allowed in equality check.
╭─[no_negation_in_equality_check.tsx:1:1]
1 │ !foo == bar
· ────
╰────
help: Remove the negation operator and use '!=' instead of '=='.
⚠ eslint-plugin-unicorn(no-negation-in-equality-check): Negated expression is not allowed in equality check.
╭─[no_negation_in_equality_check.tsx:1:1]
1 │ !foo != bar
· ────
╰────
help: Remove the negation operator and use '==' instead of '!='.
⚠ eslint-plugin-unicorn(no-negation-in-equality-check): Negated expression is not allowed in equality check.
╭─[no_negation_in_equality_check.tsx:3:14]
2 │ function x() {
3 │ return!foo === bar;
· ────
4 │ }
╰────
help: Remove the negation operator and use '!==' instead of '==='.
⚠ eslint-plugin-unicorn(no-negation-in-equality-check): Negated expression is not allowed in equality check.
╭─[no_negation_in_equality_check.tsx:3:14]
2 │ function x() {
3 │ ╭─▶ return!
4 │ ╰─▶ foo === bar;
5 │ throw!
╰────
help: Remove the negation operator and use '!==' instead of '==='.
⚠ eslint-plugin-unicorn(no-negation-in-equality-check): Negated expression is not allowed in equality check.
╭─[no_negation_in_equality_check.tsx:5:13]
4 │ foo === bar;
5 │ ╭─▶ throw!
6 │ ╰─▶ foo === bar;
7 │ }
╰────
help: Remove the negation operator and use '!==' instead of '==='.
⚠ eslint-plugin-unicorn(no-negation-in-equality-check): Negated expression is not allowed in equality check.
╭─[no_negation_in_equality_check.tsx:3:7]
2 │ foo
3 │ !(a) === b
· ────
4 │
╰────
help: Remove the negation operator and use '!==' instead of '==='.
⚠ eslint-plugin-unicorn(no-negation-in-equality-check): Negated expression is not allowed in equality check.
╭─[no_negation_in_equality_check.tsx:3:7]
2 │ foo
3 │ ![a, b].join('') === c
· ────────────────
4 │
╰────
help: Remove the negation operator and use '!==' instead of '==='.
⚠ eslint-plugin-unicorn(no-negation-in-equality-check): Negated expression is not allowed in equality check.
╭─[no_negation_in_equality_check.tsx:3:7]
2 │ foo
3 │ ! [a, b].join('') === c
· ─────────────────
4 │
╰────
help: Remove the negation operator and use '!==' instead of '==='.
⚠ eslint-plugin-unicorn(no-negation-in-equality-check): Negated expression is not allowed in equality check.
╭─[no_negation_in_equality_check.tsx:3:7]
2 │ foo
3 │ !/* comment */[a, b].join('') === c
· ─────────────────────────────
4 │
╰────
help: Remove the negation operator and use '!==' instead of '==='.