feat(meta): add meta() data with function

src/Lazy.ts

@@ -33,6 +33,10 @@ export interface LazySpec {
   optional: boolean;
 }
 
+type SchemaMetadata = Record<string, unknown>;
+
+type SchemaMetadataMutator = (obj: SchemaMetadata) => SchemaMetadata;
+
 class Lazy<T, TContext = AnyObject, TFlags extends Flags = any>
   implements ISchema<T, TContext, TFlags, undefined>
 {
@@ -148,12 +152,19 @@ class Lazy<T, TContext = AnyObject, TFlags extends Flags = any>
       : { type: 'lazy', meta: this.spec.meta, label: undefined };
   }
 
-  meta(): Record<string, unknown> | undefined;
-  meta(obj: Record<string, unknown>): Lazy<T, TContext, TFlags>;
-  meta(...args: [Record<string, unknown>?]) {
+  meta(): SchemaMetadata | undefined;
+  meta(fn: SchemaMetadataMutator): Lazy<T, TContext, TFlags>;
+  meta(obj: SchemaMetadata): Lazy<T, TContext, TFlags>;
+  meta(...args: [(SchemaMetadata | SchemaMetadataMutator)?]) {
     if (args.length === 0) return this.spec.meta;
 
-    let next = this.clone();
+    if (typeof args[0] === 'function') {
+      const schemaMutator = args[0] as SchemaMetadataMutator;
+      const next = this.clone();
+      next.spec.meta = schemaMutator(next.spec.meta || {});
+      return next;
+    }
+    const next = this.clone();
     next.spec.meta = Object.assign(next.spec.meta || {}, args[0]);
     return next;
   }

src/schema.ts

@@ -56,6 +56,8 @@ export type SchemaMetadata = keyof CustomSchemaMetadata extends never
   ? Record<PropertyKey, any>
   : CustomSchemaMetadata;
 
+type SchemaMetadataMutator = (obj: SchemaMetadata) => SchemaMetadata;
+
 export type SchemaOptions<TType, TDefault> = {
   type: string;
   spec?: Partial<SchemaSpec<TDefault>>;
@@ -245,12 +247,22 @@ export default abstract class Schema<
   }
 
   meta(): SchemaMetadata | undefined;
+  meta(fn: SchemaMetadataMutator): this;
   meta(obj: SchemaMetadata): this;
-  meta(...args: [SchemaMetadata?]) {
+  meta(...args: [(SchemaMetadata | SchemaMetadataMutator)?]) {
     if (args.length === 0) return this.spec.meta;
 
-    let next = this.clone();
-    next.spec.meta = Object.assign(next.spec.meta || {}, args[0]);
+    if (typeof args[0] === 'function') {
+      const schemaMutator = args[0] as SchemaMetadataMutator;
+      const next = this.clone();
+      next.spec.meta = schemaMutator(next.spec.meta || {});
+      return next;
+    }
+    const next = this.clone();
+    next.spec.meta = Object.assign(
+      next.spec.meta || {},
+      args[0] as SchemaMetadata,
+    );
     return next;
   }
 

test/lazy.ts

@@ -54,5 +54,29 @@ describe('lazy', function () {
         added: true,
       });
     });
+
+    it('should add meta() data', () => {
+      const schema = lazy(mapper);
+
+      expect(schema.meta({ input: 'foo' }).meta({ foo: 'bar' }).meta()).toEqual(
+        {
+          input: 'foo',
+          foo: 'bar',
+        },
+      );
+    });
+
+    it('should add meta() data with function', () => {
+      const schema = lazy(mapper);
+
+      expect(
+        schema
+          .meta({ list: ['foo'] })
+          .meta((prev: any) => ({ list: [...prev.list, 'bar'] }))
+          .meta(),
+      ).toEqual({
+        list: ['foo', 'bar'],
+      });
+    });
   });
 });

test/mixed.ts

@@ -959,6 +959,17 @@ describe('Mixed Types ', () => {
     );
   });
 
+  it('should add meta() data with function', () => {
+    expect(
+      string()
+        .meta({ list: ['foo'] })
+        .meta((prev) => ({ list: [...prev.list, 'bar'] }))
+        .meta(),
+    ).toEqual({
+      list: ['foo', 'bar'],
+    });
+  });
+
   describe('schema.describe()', () => {
     let schema: ObjectSchema<any>;
     beforeEach(() => {