fix(react): infer constructor return type instead of void (#1037)

Author: pmarkert

.changeset/constructor-return-types.md

@@ -0,0 +1,5 @@
+---
+'@doc-kit/generator-react': patch
+---
+
+Constructors now render their own class as the return type instead of `void`

packages/react/src/jsx-ast/utils/__tests__/signature.test.mjs

@@ -6,239 +6,207 @@ import { generateSignature, getFullName } from '../signature.mjs';
 describe('generateSignature', () => {
   describe('function signatures', () => {
     it('formats union return types without spaces as spaced', () => {
-      const sig = generateSignature(
-        'foo',
-        {
-          params: [],
-          return: { type: 'string|number' },
-        },
-        ''
-      );
+      const sig = generateSignature('foo', {
+        params: [],
+        return: { type: 'string|number' },
+      });
 
       assert.strictEqual(sig, 'foo(): string | number');
     });
 
     it('preserves already spaced union return types', () => {
-      const sig = generateSignature(
-        'bar',
-        {
-          params: [],
-          return: { type: 'Promise<string> | undefined' },
-        },
-        ''
-      );
+      const sig = generateSignature('bar', {
+        params: [],
+        return: { type: 'Promise<string> | undefined' },
+      });
 
       assert.strictEqual(sig, 'bar(): Promise<string> | undefined');
     });
 
     it('omits return type when undefined', () => {
-      const sig = generateSignature(
-        'baz',
-        {
-          params: [],
-          return: undefined,
-        },
-        ''
-      );
+      const sig = generateSignature('baz', {
+        params: [],
+        return: undefined,
+      });
 
       assert.strictEqual(sig, 'baz(): void');
     });
 
     it('handles empty return type', () => {
+      const sig = generateSignature('test', {
+        params: [],
+        return: null,
+      });
+
+      assert.strictEqual(sig, 'test(): void');
+    });
+
+    it('prefixes a constructor and infers its return type', () => {
       const sig = generateSignature(
-        'test',
+        'Constructor',
         {
           params: [],
-          return: null,
+          return: undefined,
         },
-        ''
+        { type: 'ctor' }
       );
 
-      assert.strictEqual(sig, 'test(): void');
+      // Node's docs omit `Returns:` on constructors, but a constructor never
+      // returns `void` — it yields an instance of its own class.
+      assert.strictEqual(sig, 'new Constructor(): Constructor');
     });
 
-    it('includes prefix when provided', () => {
+    it('keeps an explicit return type on a constructor', () => {
       const sig = generateSignature(
         'Constructor',
         {
           params: [],
-          return: undefined,
+          return: { type: 'net.Socket' },
         },
-        'new '
+        { type: 'ctor' }
       );
 
-      assert.strictEqual(sig, 'new Constructor(): void');
+      assert.strictEqual(sig, 'new Constructor(): net.Socket');
     });
 
-    it('handles complex union types with multiple pipes', () => {
+    it('falls back when a return entry carries no type', () => {
       const sig = generateSignature(
-        'complexFunc',
+        'noType',
         {
           params: [],
-          return: { type: 'string|number|boolean|null' },
+          return: { type: undefined },
         },
-        ''
+        { type: 'method' }
       );
 
+      assert.strictEqual(sig, 'noType(): void');
+    });
+
+    it('handles complex union types with multiple pipes', () => {
+      const sig = generateSignature('complexFunc', {
+        params: [],
+        return: { type: 'string|number|boolean|null' },
+      });
+
       assert.strictEqual(
         sig,
         'complexFunc(): string | number | boolean | null'
       );
     });
 
     it('filters empty parts in union types', () => {
-      const sig = generateSignature(
-        'filterFunc',
-        {
-          params: [],
-          return: { type: 'string||number|' },
-        },
-        ''
-      );
+      const sig = generateSignature('filterFunc', {
+        params: [],
+        return: { type: 'string||number|' },
+      });
 
       assert.strictEqual(sig, 'filterFunc(): string | number');
     });
   });
 
   describe('parameters', () => {
     it('handles single parameter without optional flag or default', () => {
-      const sig = generateSignature(
-        'singleParam',
-        {
-          params: [{ name: 'value', optional: false }],
-          return: undefined,
-        },
-        ''
-      );
+      const sig = generateSignature('singleParam', {
+        params: [{ name: 'value', optional: false }],
+        return: undefined,
+      });
 
       assert.strictEqual(sig, 'singleParam(value): void');
     });
 
     it('handles multiple parameters', () => {
-      const sig = generateSignature(
-        'multiParam',
-        {
-          params: [
-            { name: 'first', optional: false },
-            { name: 'second', optional: false },
-          ],
-          return: undefined,
-        },
-        ''
-      );
+      const sig = generateSignature('multiParam', {
+        params: [
+          { name: 'first', optional: false },
+          { name: 'second', optional: false },
+        ],
+        return: undefined,
+      });
 
       assert.strictEqual(sig, 'multiParam(first, second): void');
     });
 
     it('marks optional parameters with question mark', () => {
-      const sig = generateSignature(
-        'optionalParam',
-        {
-          params: [
-            { name: 'required', optional: false },
-            { name: 'optional', optional: true },
-          ],
-          return: undefined,
-        },
-        ''
-      );
+      const sig = generateSignature('optionalParam', {
+        params: [
+          { name: 'required', optional: false },
+          { name: 'optional', optional: true },
+        ],
+        return: undefined,
+      });
 
       assert.strictEqual(sig, 'optionalParam(required, optional?): void');
     });
 
     it('marks parameters with defaults as optional', () => {
-      const sig = generateSignature(
-        'defaultParam',
-        {
-          params: [
-            { name: 'normal', optional: false },
-            { name: 'withDefault', optional: false, default: 'defaultValue' },
-          ],
-          return: undefined,
-        },
-        ''
-      );
+      const sig = generateSignature('defaultParam', {
+        params: [
+          { name: 'normal', optional: false },
+          { name: 'withDefault', optional: false, default: 'defaultValue' },
+        ],
+        return: undefined,
+      });
 
       assert.strictEqual(sig, 'defaultParam(normal, withDefault?): void');
     });
 
     it('handles parameters that are both optional and have defaults', () => {
-      const sig = generateSignature(
-        'bothOptionalAndDefault',
-        {
-          params: [{ name: 'param', optional: true, default: 'value' }],
-          return: undefined,
-        },
-        ''
-      );
+      const sig = generateSignature('bothOptionalAndDefault', {
+        params: [{ name: 'param', optional: true, default: 'value' }],
+        return: undefined,
+      });
 
       assert.strictEqual(sig, 'bothOptionalAndDefault(param?): void');
     });
 
     it('handles empty params array', () => {
-      const sig = generateSignature(
-        'noParams',
-        {
-          params: [],
-          return: { type: 'string' },
-        },
-        ''
-      );
+      const sig = generateSignature('noParams', {
+        params: [],
+        return: { type: 'string' },
+      });
 
       assert.strictEqual(sig, 'noParams(): string');
     });
 
     it('handles params without optional property', () => {
-      const sig = generateSignature(
-        'implicitOptional',
-        {
-          params: [{ name: 'param1' }, { name: 'param2', default: 'value' }],
-          return: undefined,
-        },
-        ''
-      );
+      const sig = generateSignature('implicitOptional', {
+        params: [{ name: 'param1' }, { name: 'param2', default: 'value' }],
+        return: undefined,
+      });
 
       assert.strictEqual(sig, 'implicitOptional(param1, param2?): void');
     });
   });
 
   describe('class signatures', () => {
     it('generates class signature with extends clause', () => {
-      const sig = generateSignature(
-        'MyClass',
-        {
-          params: [],
-          extends: { type: 'BaseClass' },
-        },
-        ''
-      );
+      const sig = generateSignature('MyClass', {
+        params: [],
+        extends: { type: 'BaseClass' },
+      });
 
       assert.strictEqual(sig, 'class MyClass extends BaseClass');
     });
 
-    it('generates class signature with extends and prefix', () => {
+    it('does not prefix a class signature', () => {
       const sig = generateSignature(
         'MyClass',
         {
           params: [],
           extends: { type: 'BaseClass' },
         },
-        'abstract '
+        { type: 'class' }
       );
 
-      assert.strictEqual(sig, 'class abstract MyClass extends BaseClass');
+      assert.strictEqual(sig, 'class MyClass extends BaseClass');
     });
 
     it('ignores params and return type for class with extends', () => {
-      const sig = generateSignature(
-        'MyClass',
-        {
-          params: [{ name: 'ignored', optional: false }],
-          return: { type: 'ignored' },
-          extends: { type: 'BaseClass' },
-        },
-        ''
-      );
+      const sig = generateSignature('MyClass', {
+        params: [{ name: 'ignored', optional: false }],
+        return: { type: 'ignored' },
+        extends: { type: 'BaseClass' },
+      });
 
       assert.strictEqual(sig, 'class MyClass extends BaseClass');
     });
@@ -250,7 +218,7 @@ describe('generateSignature', () => {
           params: [{ name: 'param', optional: false }],
           return: { type: 'MyClass' },
         },
-        'new '
+        { type: 'ctor' }
       );
 
       assert.strictEqual(sig, 'new MyClass(param): MyClass');
@@ -259,27 +227,19 @@ describe('generateSignature', () => {
 
   describe('edge cases', () => {
     it('handles null return type', () => {
-      const sig = generateSignature(
-        'nullReturn',
-        {
-          params: [],
-          return: null,
-        },
-        ''
-      );
+      const sig = generateSignature('nullReturn', {
+        params: [],
+        return: null,
+      });
 
       assert.strictEqual(sig, 'nullReturn(): void');
     });
 
     it('handles missing extends property', () => {
-      const sig = generateSignature(
-        'NoExtends',
-        {
-          params: [{ name: 'param' }],
-          return: { type: 'void' },
-        },
-        ''
-      );
+      const sig = generateSignature('NoExtends', {
+        params: [{ name: 'param' }],
+        return: { type: 'void' },
+      });
 
       assert.strictEqual(sig, 'NoExtends(param): void');
     });