feat(linter) eslint plugin unicorn: no zero fractions (#1464)

crates/oxc_linter/src/rules.rs

@@ -171,6 +171,7 @@ mod unicorn {
     pub mod no_useless_fallback_in_spread;
     pub mod no_useless_promise_resolve_reject;
     pub mod no_useless_switch_case;
+    pub mod no_zero_fractions;
     pub mod number_literal_case;
     pub mod prefer_add_event_listener;
     pub mod prefer_array_flat_map;
@@ -333,6 +334,7 @@ oxc_macros::declare_all_lint_rules! {
     unicorn::no_useless_fallback_in_spread,
     unicorn::no_useless_promise_resolve_reject,
     unicorn::no_useless_switch_case,
+    unicorn::no_zero_fractions,
     unicorn::number_literal_case,
     unicorn::prefer_add_event_listener,
     unicorn::prefer_array_flat_map,

crates/oxc_linter/src/rules/unicorn/no_zero_fractions.rs

@@ -0,0 +1,137 @@
+use oxc_ast::AstKind;
+use oxc_diagnostics::{
+    miette::{self, Diagnostic},
+    thiserror::Error,
+};
+use oxc_macros::declare_oxc_lint;
+use oxc_span::Span;
+
+use crate::{context::LintContext, rule::Rule, AstNode, Fix};
+
+#[derive(Debug, Error, Diagnostic)]
+enum NoZeroFractionsDiagnostic {
+    #[error("eslint-plugin-unicorn(no-zero-fractions): Don't use a zero fraction in the number.")]
+    #[diagnostic(severity(warning), help("Replace the number literal with `{1}`"))]
+    ZeroFraction(#[label] Span, String),
+    #[error("eslint-plugin-unicorn(no-zero-fractions): Don't use a dangling dot in the number.")]
+    #[diagnostic(severity(warning), help("Replace the number literal with `{1}`"))]
+    DanglingDot(#[label] Span, String),
+}
+
+#[derive(Debug, Default, Clone)]
+pub struct NoZeroFractions;
+
+declare_oxc_lint!(
+    /// ### What it does
+    ///
+    /// Prevents the use of zero fractions.
+    ///
+    /// ### Why is this bad?
+    ///
+    /// There is no difference in JavaScript between, for example, `1`, `1.0` and `1.`, so prefer the former for consistency and brevity.
+    ///
+    /// ### Example
+    /// ```javascript
+    /// // Bad
+    /// const foo = 1.0;
+    /// const foo = -1.0;
+    /// const foo = 123_456.000_000;
+    ///
+    /// // Good
+    /// const foo = 1;
+    /// const foo = -1;
+    /// const foo = 123456;
+    /// const foo = 1.1;
+    /// ```
+    NoZeroFractions,
+    style
+);
+
+impl Rule for NoZeroFractions {
+    fn run<'a>(&self, node: &AstNode<'a>, ctx: &LintContext<'a>) {
+        let AstKind::NumberLiteral(number_literal) = node.kind() else {
+            return;
+        };
+
+        let Some((fmt, is_dangling_dot)) = format_raw(number_literal.raw) else { return };
+        if fmt == number_literal.raw {
+            return;
+        };
+
+        ctx.diagnostic_with_fix(
+            if is_dangling_dot {
+                NoZeroFractionsDiagnostic::DanglingDot(number_literal.span, fmt.clone())
+            } else {
+                NoZeroFractionsDiagnostic::ZeroFraction(number_literal.span, fmt.clone())
+            },
+            || Fix::new(fmt, number_literal.span),
+        );
+    }
+}
+
+fn format_raw(raw: &str) -> Option<(String, bool)> {
+    let (before, after_and_dot) = raw.split_once('.')?;
+    let mut after_parts = after_and_dot.splitn(2, |c: char| !c.is_ascii_digit() && c != '_');
+    let dot_and_fractions = after_parts.next()?;
+    let after = after_parts.next().unwrap_or("");
+
+    let fixed_dot_and_fractions =
+        dot_and_fractions.trim_end_matches(|c: char| c == '0' || c == '.' || c == '_');
+    let formatted = format!(
+        "{}{}{}{}",
+        if before.is_empty() && fixed_dot_and_fractions.is_empty() { "0" } else { before },
+        if fixed_dot_and_fractions.is_empty() { "" } else { "." },
+        fixed_dot_and_fractions,
+        after
+    );
+
+    Some((formatted, dot_and_fractions.is_empty()))
+}
+
+#[test]
+fn test() {
+    use crate::tester::Tester;
+
+    let pass = vec![
+        r#"const foo = "123.1000""#,
+        r#"foo("123.1000")"#,
+        r"const foo = 1",
+        r"const foo = 1 + 2",
+        r"const foo = -1",
+        r"const foo = 123123123",
+        r"const foo = 1.1",
+        r"const foo = -1.1",
+        r"const foo = 123123123.4",
+        r"const foo = 1e3",
+        r"1 .toString()",
+    ];
+
+    let fail = vec![
+        r"const foo = 1.0",
+        r"const foo = 1.0 + 1",
+        r"foo(1.0 + 1)",
+        r"const foo = 1.00",
+        r"const foo = 1.00000",
+        r"const foo = -1.0",
+        r"const foo = 123123123.0",
+        r"const foo = 123.11100000000",
+        r"const foo = 1.",
+        r"const foo = +1.",
+        r"const foo = -1.",
+        r"const foo = 1.e10",
+        r"const foo = +1.e-10",
+        r"const foo = -1.e+10",
+        r"const foo = (1.).toString()",
+        r"1.00.toFixed(2)",
+        r"1.00 .toFixed(2)",
+        r"(1.00).toFixed(2)",
+        r"1.00?.toFixed(2)",
+        r"a = .0;",
+        r"a = .0.toString()",
+        r"function foo(){return.0}",
+        r"function foo(){return.0.toString()}",
+        r"function foo(){return.0+.1}",
+    ];
+
+    Tester::new_without_config(NoZeroFractions::NAME, pass, fail).test_and_snapshot();
+}

crates/oxc_linter/src/snapshots/no_zero_fractions.snap

@@ -0,0 +1,173 @@
+---
+source: crates/oxc_linter/src/tester.rs
+expression: no_zero_fractions
+---
+  ⚠ eslint-plugin-unicorn(no-zero-fractions): Don't use a zero fraction in the number.
+   ╭─[no_zero_fractions.tsx:1:1]
+ 1 │ const foo = 1.0
+   ·             ───
+   ╰────
+  help: Replace the number literal with `1`
+
+  ⚠ eslint-plugin-unicorn(no-zero-fractions): Don't use a zero fraction in the number.
+   ╭─[no_zero_fractions.tsx:1:1]
+ 1 │ const foo = 1.0 + 1
+   ·             ───
+   ╰────
+  help: Replace the number literal with `1`
+
+  ⚠ eslint-plugin-unicorn(no-zero-fractions): Don't use a zero fraction in the number.
+   ╭─[no_zero_fractions.tsx:1:1]
+ 1 │ foo(1.0 + 1)
+   ·     ───
+   ╰────
+  help: Replace the number literal with `1`
+
+  ⚠ eslint-plugin-unicorn(no-zero-fractions): Don't use a zero fraction in the number.
+   ╭─[no_zero_fractions.tsx:1:1]
+ 1 │ const foo = 1.00
+   ·             ────
+   ╰────
+  help: Replace the number literal with `1`
+
+  ⚠ eslint-plugin-unicorn(no-zero-fractions): Don't use a zero fraction in the number.
+   ╭─[no_zero_fractions.tsx:1:1]
+ 1 │ const foo = 1.00000
+   ·             ───────
+   ╰────
+  help: Replace the number literal with `1`
+
+  ⚠ eslint-plugin-unicorn(no-zero-fractions): Don't use a zero fraction in the number.
+   ╭─[no_zero_fractions.tsx:1:1]
+ 1 │ const foo = -1.0
+   ·              ───
+   ╰────
+  help: Replace the number literal with `1`
+
+  ⚠ eslint-plugin-unicorn(no-zero-fractions): Don't use a zero fraction in the number.
+   ╭─[no_zero_fractions.tsx:1:1]
+ 1 │ const foo = 123123123.0
+   ·             ───────────
+   ╰────
+  help: Replace the number literal with `123123123`
+
+  ⚠ eslint-plugin-unicorn(no-zero-fractions): Don't use a zero fraction in the number.
+   ╭─[no_zero_fractions.tsx:1:1]
+ 1 │ const foo = 123.11100000000
+   ·             ───────────────
+   ╰────
+  help: Replace the number literal with `123.111`
+
+  ⚠ eslint-plugin-unicorn(no-zero-fractions): Don't use a dangling dot in the number.
+   ╭─[no_zero_fractions.tsx:1:1]
+ 1 │ const foo = 1.
+   ·             ──
+   ╰────
+  help: Replace the number literal with `1`
+
+  ⚠ eslint-plugin-unicorn(no-zero-fractions): Don't use a dangling dot in the number.
+   ╭─[no_zero_fractions.tsx:1:1]
+ 1 │ const foo = +1.
+   ·              ──
+   ╰────
+  help: Replace the number literal with `1`
+
+  ⚠ eslint-plugin-unicorn(no-zero-fractions): Don't use a dangling dot in the number.
+   ╭─[no_zero_fractions.tsx:1:1]
+ 1 │ const foo = -1.
+   ·              ──
+   ╰────
+  help: Replace the number literal with `1`
+
+  ⚠ eslint-plugin-unicorn(no-zero-fractions): Don't use a dangling dot in the number.
+   ╭─[no_zero_fractions.tsx:1:1]
+ 1 │ const foo = 1.e10
+   ·             ─────
+   ╰────
+  help: Replace the number literal with `110`
+
+  ⚠ eslint-plugin-unicorn(no-zero-fractions): Don't use a dangling dot in the number.
+   ╭─[no_zero_fractions.tsx:1:1]
+ 1 │ const foo = +1.e-10
+   ·              ──────
+   ╰────
+  help: Replace the number literal with `1-10`
+
+  ⚠ eslint-plugin-unicorn(no-zero-fractions): Don't use a dangling dot in the number.
+   ╭─[no_zero_fractions.tsx:1:1]
+ 1 │ const foo = -1.e+10
+   ·              ──────
+   ╰────
+  help: Replace the number literal with `1+10`
+
+  ⚠ eslint-plugin-unicorn(no-zero-fractions): Don't use a dangling dot in the number.
+   ╭─[no_zero_fractions.tsx:1:1]
+ 1 │ const foo = (1.).toString()
+   ·              ──
+   ╰────
+  help: Replace the number literal with `1`
+
+  ⚠ eslint-plugin-unicorn(no-zero-fractions): Don't use a zero fraction in the number.
+   ╭─[no_zero_fractions.tsx:1:1]
+ 1 │ 1.00.toFixed(2)
+   · ────
+   ╰────
+  help: Replace the number literal with `1`
+
+  ⚠ eslint-plugin-unicorn(no-zero-fractions): Don't use a zero fraction in the number.
+   ╭─[no_zero_fractions.tsx:1:1]
+ 1 │ 1.00 .toFixed(2)
+   · ────
+   ╰────
+  help: Replace the number literal with `1`
+
+  ⚠ eslint-plugin-unicorn(no-zero-fractions): Don't use a zero fraction in the number.
+   ╭─[no_zero_fractions.tsx:1:1]
+ 1 │ (1.00).toFixed(2)
+   ·  ────
+   ╰────
+  help: Replace the number literal with `1`
+
+  ⚠ eslint-plugin-unicorn(no-zero-fractions): Don't use a zero fraction in the number.
+   ╭─[no_zero_fractions.tsx:1:1]
+ 1 │ 1.00?.toFixed(2)
+   · ────
+   ╰────
+  help: Replace the number literal with `1`
+
+  ⚠ eslint-plugin-unicorn(no-zero-fractions): Don't use a zero fraction in the number.
+   ╭─[no_zero_fractions.tsx:1:1]
+ 1 │ a = .0;
+   ·     ──
+   ╰────
+  help: Replace the number literal with `0`
+
+  ⚠ eslint-plugin-unicorn(no-zero-fractions): Don't use a zero fraction in the number.
+   ╭─[no_zero_fractions.tsx:1:1]
+ 1 │ a = .0.toString()
+   ·     ──
+   ╰────
+  help: Replace the number literal with `0`
+
+  ⚠ eslint-plugin-unicorn(no-zero-fractions): Don't use a zero fraction in the number.
+   ╭─[no_zero_fractions.tsx:1:1]
+ 1 │ function foo(){return.0}
+   ·                      ──
+   ╰────
+  help: Replace the number literal with `0`
+
+  ⚠ eslint-plugin-unicorn(no-zero-fractions): Don't use a zero fraction in the number.
+   ╭─[no_zero_fractions.tsx:1:1]
+ 1 │ function foo(){return.0.toString()}
+   ·                      ──
+   ╰────
+  help: Replace the number literal with `0`
+
+  ⚠ eslint-plugin-unicorn(no-zero-fractions): Don't use a zero fraction in the number.
+   ╭─[no_zero_fractions.tsx:1:1]
+ 1 │ function foo(){return.0+.1}
+   ·                      ──
+   ╰────
+  help: Replace the number literal with `0`
+
+