feat(linter) eslint-plugin-unicorn no-static-only-class (#1161)

crates/oxc_linter/src/rules.rs

@@ -149,6 +149,7 @@ mod unicorn {
     pub mod no_invalid_remove_event_listener;
     pub mod no_new_array;
     pub mod no_object_as_default_parameter;
+    pub mod no_static_only_class;
     pub mod no_thenable;
     pub mod no_unnecessary_await;
     pub mod prefer_array_flat_map;
@@ -278,6 +279,7 @@ oxc_macros::declare_all_lint_rules! {
     unicorn::no_invalid_remove_event_listener,
     unicorn::no_new_array,
     unicorn::no_object_as_default_parameter,
+    unicorn::no_static_only_class,
     unicorn::no_thenable,
     unicorn::no_unnecessary_await,
     unicorn::prefer_array_flat_map,

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

@@ -0,0 +1,156 @@
+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};
+
+#[derive(Debug, Error, Diagnostic)]
+#[error(
+    "eslint-plugin-unicorn(no-static-only-class): Disallow classes that only have static members."
+)]
+#[diagnostic(
+    severity(warning),
+    help("A class with only static members could just be an object instead.")
+)]
+struct NoStaticOnlyClassDiagnostic(#[label] pub Span);
+
+#[derive(Debug, Default, Clone)]
+pub struct NoStaticOnlyClass;
+
+declare_oxc_lint!(
+    /// ### What it does
+    ///
+    /// Disallow classes that only have static members.
+    ///
+    /// ### Why is this bad?
+    ///
+    /// A class with only static members could just be an object instead.
+    ///
+    ///
+    /// ### Example
+    /// ```javascript
+    /// // Bad
+    /// class A {
+    ///     static a() {}
+    /// }
+    ///
+    /// // Good
+    /// class A {
+    ///     static a() {}
+    ///
+    ///     constructor() {}
+    /// }
+    /// ```
+    NoStaticOnlyClass,
+    pedantic
+);
+
+impl Rule for NoStaticOnlyClass {
+    fn run<'a>(&self, node: &AstNode<'a>, ctx: &LintContext<'a>) {
+        let AstKind::Class(class) = node.kind() else { return };
+
+        if class.super_class.is_some() {
+            return;
+        }
+        if class.decorators.len() > 0 {
+            return;
+        }
+        if class.body.body.len() == 0 {
+            return;
+        }
+        if class.body.body.iter().any(|node| {
+            match node {
+                oxc_ast::ast::ClassElement::MethodDefinition(v) => {
+                    if v.accessibility.is_some() {
+                        return true;
+                    }
+                }
+                oxc_ast::ast::ClassElement::PropertyDefinition(v) => {
+                    if v.accessibility.is_some() || v.readonly || v.declare {
+                        return true;
+                    }
+                }
+                oxc_ast::ast::ClassElement::TSAbstractMethodDefinition(v) => {
+                    if v.method_definition.accessibility.is_some() {
+                        return true;
+                    }
+                }
+                oxc_ast::ast::ClassElement::TSAbstractPropertyDefinition(v) => {
+                    if v.property_definition.accessibility.is_some() {
+                        return true;
+                    }
+                }
+                oxc_ast::ast::ClassElement::AccessorProperty(_)
+                | oxc_ast::ast::ClassElement::StaticBlock(_)
+                | oxc_ast::ast::ClassElement::TSIndexSignature(_) => {}
+            }
+
+            if node.r#static() {
+                if let Some(k) = node.property_key() {
+                    return k.is_private_identifier();
+                }
+                return false;
+            }
+            true
+        }) {
+            return;
+        }
+
+        ctx.diagnostic(NoStaticOnlyClassDiagnostic(class.span));
+    }
+}
+
+#[test]
+fn test() {
+    use crate::tester::Tester;
+
+    let pass = vec![
+        r#"class A {}"#,
+        r#"const A = class {}"#,
+        r#"class A extends B { static a() {}; }"#,
+        r#"const A = class extends B { static a() {}; }"#,
+        r#"class A { a() {} }"#,
+        r#"class A { constructor() {} }"#,
+        r#"class A { get a() {} }"#,
+        r#"class A { set a(value) {} }"#,
+        r#"class A3 { static #a() {}; }"#,
+        r#"class A3 { static #a = 1; }"#,
+        r#"const A3 = class { static #a() {}; }"#,
+        r#"const A3 = class { static #a = 1; }"#,
+        r#"class A2 { static {}; }"#,
+        r#"class A { static #a() {}; }"#,
+        r#"class A { static #a = 1; }"#,
+        r#"const A = class { static #a() {}; }"#,
+        r#"const A = class { static #a = 1; }"#,
+        r#"@decorator class A { static  a = 1; }"#,
+        r#"class A { static public a = 1; }"#,
+        r#"class A { static private a = 1; }"#,
+        r#"class A { static readonly a = 1; }"#,
+        r#"class A { static declare a = 1; }"#,
+        r#"class A { static {}; }"#,
+        r#"class A2 { static #a() {}; }"#,
+        r#"class A2 { static #a = 1; }"#,
+        r#"const A2 = class { static #a() {}; }"#,
+        r#"const A2 = class { static #a = 1; }"#,
+        r#"class A2 { static {}; }"#,
+    ];
+
+    let fail = vec![
+        r#"class A { static a() {}; }"#,
+        r#"class A { static a() {} }"#,
+        r#"const A = class A { static a() {}; }"#,
+        r#"const A = class { static a() {}; }"#,
+        r#"class A { static constructor() {}; }"#,
+        r#"export default class A { static a() {}; }"#,
+        r#"export default class { static a() {}; }"#,
+        r#"export class A { static a() {}; }"#,
+        r#"class A {static [this.a] = 1}"#,
+        r#"class A { static a() {} }"#,
+    ];
+
+    Tester::new_without_config(NoStaticOnlyClass::NAME, pass, fail).test_and_snapshot();
+}

crates/oxc_linter/src/snapshots/no_static_only_class.snap

@@ -0,0 +1,75 @@
+---
+source: crates/oxc_linter/src/tester.rs
+expression: no_static_only_class
+---
+  ⚠ eslint-plugin-unicorn(no-static-only-class): Disallow classes that only have static members.
+   ╭─[no_static_only_class.tsx:1:1]
+ 1 │ class A { static a() {}; }
+   · ──────────────────────────
+   ╰────
+  help: A class with only static members could just be an object instead.
+
+  ⚠ eslint-plugin-unicorn(no-static-only-class): Disallow classes that only have static members.
+   ╭─[no_static_only_class.tsx:1:1]
+ 1 │ class A { static a() {} }
+   · ─────────────────────────
+   ╰────
+  help: A class with only static members could just be an object instead.
+
+  ⚠ eslint-plugin-unicorn(no-static-only-class): Disallow classes that only have static members.
+   ╭─[no_static_only_class.tsx:1:1]
+ 1 │ const A = class A { static a() {}; }
+   ·           ──────────────────────────
+   ╰────
+  help: A class with only static members could just be an object instead.
+
+  ⚠ eslint-plugin-unicorn(no-static-only-class): Disallow classes that only have static members.
+   ╭─[no_static_only_class.tsx:1:1]
+ 1 │ const A = class { static a() {}; }
+   ·           ────────────────────────
+   ╰────
+  help: A class with only static members could just be an object instead.
+
+  ⚠ eslint-plugin-unicorn(no-static-only-class): Disallow classes that only have static members.
+   ╭─[no_static_only_class.tsx:1:1]
+ 1 │ class A { static constructor() {}; }
+   · ────────────────────────────────────
+   ╰────
+  help: A class with only static members could just be an object instead.
+
+  ⚠ eslint-plugin-unicorn(no-static-only-class): Disallow classes that only have static members.
+   ╭─[no_static_only_class.tsx:1:1]
+ 1 │ export default class A { static a() {}; }
+   ·                ──────────────────────────
+   ╰────
+  help: A class with only static members could just be an object instead.
+
+  ⚠ eslint-plugin-unicorn(no-static-only-class): Disallow classes that only have static members.
+   ╭─[no_static_only_class.tsx:1:1]
+ 1 │ export default class { static a() {}; }
+   ·                ────────────────────────
+   ╰────
+  help: A class with only static members could just be an object instead.
+
+  ⚠ eslint-plugin-unicorn(no-static-only-class): Disallow classes that only have static members.
+   ╭─[no_static_only_class.tsx:1:1]
+ 1 │ export class A { static a() {}; }
+   ·        ──────────────────────────
+   ╰────
+  help: A class with only static members could just be an object instead.
+
+  ⚠ eslint-plugin-unicorn(no-static-only-class): Disallow classes that only have static members.
+   ╭─[no_static_only_class.tsx:1:1]
+ 1 │ class A {static [this.a] = 1}
+   · ─────────────────────────────
+   ╰────
+  help: A class with only static members could just be an object instead.
+
+  ⚠ eslint-plugin-unicorn(no-static-only-class): Disallow classes that only have static members.
+   ╭─[no_static_only_class.tsx:1:1]
+ 1 │ class A { static a() {} }
+   · ─────────────────────────
+   ╰────
+  help: A class with only static members could just be an object instead.
+
+