fix(isolated-declarations): method following an abstract method gets dropped (#4024)

close: #4019

crates/oxc_ast/src/ast_impl/js.rs

@@ -1298,6 +1298,12 @@ impl MethodDefinitionKind {
     }
 }
 
+impl MethodDefinitionType {
+    pub fn is_abstract(&self) -> bool {
+        matches!(self, Self::TSAbstractMethodDefinition)
+    }
+}
+
 impl<'a> PrivateIdentifier<'a> {
     pub fn new(span: Span, name: Atom<'a>) -> Self {
         Self { span, name }

crates/oxc_isolated_declarations/src/class.rs

@@ -329,7 +329,7 @@ impl<'a> IsolatedDeclarations<'a> {
             match element {
                 ClassElement::StaticBlock(_) => {}
                 ClassElement::MethodDefinition(ref method) => {
-                    if method.value.body.is_none() {
+                    if !method.r#type.is_abstract() && method.value.body.is_none() {
                         is_function_overloads = true;
                     } else if is_function_overloads {
                         // Skip implementation of function overloads

crates/oxc_isolated_declarations/tests/fixtures/class.ts

@@ -6,4 +6,10 @@ export class Bar {
   public constructor(a: number = 0) {}
 }
 
-export class Zoo { foo<F>(f: F): F { return f } }
+export class Zoo { foo<F>(f: F): F { return f } }
+
+export abstract class Qux {
+  abstract foo(): void;
+  bar(): void {}
+  baz(): void {}
+}

crates/oxc_isolated_declarations/tests/snapshots/class.snap

@@ -13,3 +13,8 @@ export declare class Bar {
 export declare class Zoo {
 	foo<F>(f: F): F;
 }
+export declare abstract class Qux {
+	abstract foo(): void;
+	bar(): void;
+	baz(): void;
+}