fix(linter): improve prefer_namespace_keyword rule (#4751)

fix: #4651
This commit enhances the `prefer_namespace_keyword` rule in the
TypeScript linter: Add support for detecting and fixing nested module
declarations (e.g., module A.B {})

- Introduce helper functions `is_nest_module`, `is_valid_module`, and
`is_invalid_module` to improve code readability and maintainability
- Refactor the main `run` function to use these new helper functions
- Update test cases to cover nested module scenarios
- Improve error reporting for nested modules

crates/oxc_linter/src/rules/typescript/prefer_namespace_keyword.rs

@@ -1,5 +1,5 @@
 use oxc_ast::{
-    ast::{TSModuleDeclarationKind, TSModuleDeclarationName},
+    ast::{TSModuleDeclaration, TSModuleDeclarationKind, TSModuleDeclarationName},
     AstKind,
 };
 use oxc_diagnostics::OxcDiagnostic;
@@ -34,13 +34,27 @@ declare_oxc_lint!(
     fix
 );
 
+fn is_nest_module(node: &AstNode, ctx: &LintContext<'_>) -> bool {
+    ctx.nodes()
+        .parent_node(node.id())
+        .map_or(false, |parent_node| is_valid_module_node(parent_node))
+}
+
+fn is_valid_module_node(node: &AstNode) -> bool {
+    matches!(node.kind(), AstKind::TSModuleDeclaration(module) if is_valid_module(module))
+}
+
+fn is_valid_module(module: &TSModuleDeclaration) -> bool {
+    !module.id.is_string_literal()
+        && matches!(module.id, TSModuleDeclarationName::Identifier(_))
+        && module.kind == TSModuleDeclarationKind::Module
+}
+
 impl Rule for PreferNamespaceKeyword {
     fn run<'a>(&self, node: &AstNode<'a>, ctx: &LintContext<'a>) {
         let AstKind::TSModuleDeclaration(module) = node.kind() else { return };
-        if module.id.is_string_literal()
-            || !matches!(module.id, TSModuleDeclarationName::Identifier(_))
-            || module.kind != TSModuleDeclarationKind::Module
-        {
+
+        if !is_valid_module(module) || is_nest_module(node, ctx) {
             return;
         }
 
@@ -74,32 +88,48 @@ fn test() {
 
     let fail = vec![
         "module foo {}",
+        "module A.B {}",
         "declare module foo {}",
         "
-			declare module foo {
-			  declare module bar {}
-			}
-			      ",
-        "declare global {
+        declare module foo {
+          declare module bar {}
+        }
+        ",
+        "
+        declare global {
             module foo {}
         }
         ",
     ];
 
     let fix = vec![
         ("module foo {}", "namespace foo {}", None),
+        ("module A.B {}", "namespace A.B {}", None),
+        (
+            "
+            module A {
+              module B {}
+            }
+            ",
+            "
+            namespace A {
+              namespace B {}
+            }
+            ",
+            None,
+        ),
         ("declare module foo {}", "declare namespace foo {}", None),
         (
             "
-			declare module foo {
-			  declare module bar {}
-			}
-			      ",
+            declare module foo {
+              declare module bar {}
+            }
+            ",
             "
-			declare namespace foo {
-			  declare namespace bar {}
-			}
-			      ",
+            declare namespace foo {
+              declare namespace bar {}
+            }
+            ",
             None,
         ),
     ];

crates/oxc_linter/src/snapshots/prefer_namespace_keyword.snap

@@ -8,6 +8,13 @@ source: crates/oxc_linter/src/tester.rs
    ╰────
   help: Replace `module` with `namespace`.
 
+  ⚠ typescript-eslint(prefer-namespace-keyword): Use 'namespace' instead of 'module' to declare custom TypeScript modules.
+   ╭─[prefer_namespace_keyword.tsx:1:1]
+ 1 │ module A.B {}
+   · ─────────────
+   ╰────
+  help: Replace `module` with `namespace`.
+
   ⚠ typescript-eslint(prefer-namespace-keyword): Use 'namespace' instead of 'module' to declare custom TypeScript modules.
    ╭─[prefer_namespace_keyword.tsx:1:1]
  1 │ declare module foo {}
@@ -16,29 +23,29 @@ source: crates/oxc_linter/src/tester.rs
   help: Replace `module` with `namespace`.
 
   ⚠ typescript-eslint(prefer-namespace-keyword): Use 'namespace' instead of 'module' to declare custom TypeScript modules.
-   ╭─[prefer_namespace_keyword.tsx:2:4]
+   ╭─[prefer_namespace_keyword.tsx:2:9]
  1 │     
- 2 │ ╭─▶             declare module foo {
- 3 │ │                 declare module bar {}
- 4 │ ╰─▶             }
- 5 │                       
+ 2 │ ╭─▶         declare module foo {
+ 3 │ │             declare module bar {}
+ 4 │ ╰─▶         }
+ 5 │             
    ╰────
   help: Replace `module` with `namespace`.
 
   ⚠ typescript-eslint(prefer-namespace-keyword): Use 'namespace' instead of 'module' to declare custom TypeScript modules.
-   ╭─[prefer_namespace_keyword.tsx:3:6]
- 2 │             declare module foo {
- 3 │               declare module bar {}
-   ·               ─────────────────────
- 4 │             }
+   ╭─[prefer_namespace_keyword.tsx:3:11]
+ 2 │         declare module foo {
+ 3 │           declare module bar {}
+   ·           ─────────────────────
+ 4 │         }
    ╰────
   help: Replace `module` with `namespace`.
 
   ⚠ typescript-eslint(prefer-namespace-keyword): Use 'namespace' instead of 'module' to declare custom TypeScript modules.
-   ╭─[prefer_namespace_keyword.tsx:2:13]
- 1 │ declare global {
- 2 │             module foo {}
+   ╭─[prefer_namespace_keyword.tsx:3:13]
+ 2 │         declare global {
+ 3 │             module foo {}
    ·             ─────────────
- 3 │         }
+ 4 │         }
    ╰────
   help: Replace `module` with `namespace`.