feat(shape): added additionalProperties arg

Author: webdeveric

src/predicate/factory/shape.ts

@@ -1,4 +1,5 @@
 /* eslint-disable @typescript-eslint/ban-types */
+import { hasAdditionalProperties } from '../../hasAdditionalProperties.js';
 import { isAnyObject } from '../isAnyObject.js';
 
 import { literal } from './literal.js';
@@ -40,24 +41,26 @@ export type InferTypeFromShape<Shape extends ObjectShapeRecord<object>> = {
 
 export const shape = <Type extends object, Shape extends ObjectShapeRecord<Type> = ObjectShapeRecord<Type>>(
   objectShape: Shape,
+  additionalProperties = true,
 ): TypePredicateFn<Pretty<Type & InferTypeFromShape<Shape>>> => {
-  const entries: [key: string | symbol, predicate: TypePredicateFn<unknown>][] = Reflect.ownKeys(objectShape).map(
-    (key) => {
-      const value = Reflect.get(objectShape, key);
-
-      const predicate =
-        typeof value === 'function'
-          ? (value as TypePredicateFn<unknown>)
-          : value instanceof RegExp
-            ? matching(value)
-            : isAnyObject(value)
-              ? shape(value)
-              : literal(value);
-
-      return [key, predicate];
-    },
-  );
+  const knownProperties = Reflect.ownKeys(objectShape);
+  const entries: [key: string | symbol, predicate: TypePredicateFn<unknown>][] = knownProperties.map((key) => {
+    const value = Reflect.get(objectShape, key);
+
+    const predicate =
+      typeof value === 'function'
+        ? (value as TypePredicateFn<unknown>)
+        : value instanceof RegExp
+          ? matching(value)
+          : isAnyObject(value)
+            ? shape(value)
+            : literal(value);
+
+    return [key, predicate];
+  });
 
   return (input: unknown): input is Pretty<Type & InferTypeFromShape<Shape>> =>
-    isAnyObject(input) && entries.every(([key, predicate]) => predicate(Reflect.get(input, key)));
+    isAnyObject(input) &&
+    entries.every(([key, predicate]) => predicate(Reflect.get(input, key))) &&
+    (additionalProperties || !hasAdditionalProperties(input, knownProperties));
 };

test/predicate/factory/shape.test.ts

@@ -23,7 +23,9 @@ describe('shape()', () => {
 
   type User = {
     name: Name;
-    title: string;
+    job: {
+      title: string;
+    };
     role: Role;
     value: number;
     age?: number;
@@ -39,7 +41,9 @@ describe('shape()', () => {
 
   const userShape = {
     name: isName,
-    title: /software/i,
+    job: {
+      title: /\bsoftware\b/i,
+    },
     role: Role.User,
     value: range(0, 100),
     [valueSymbol]: range(0, 100_000),
@@ -53,19 +57,21 @@ describe('shape()', () => {
     tuple: ['PI', Math.PI],
   } satisfies UserShape;
 
-  const fn = shape(userShape);
-
   it('Returns a type predicate function', () => {
-    expect(fn).instanceOf(Function);
+    expect(shape(userShape)).instanceOf(Function);
   });
 
   it('Checks string and symbol properties', () => {
+    const fn = shape(userShape);
+
     expect(fn({})).toBeFalsy();
 
     expect(
       fn({
         name: 'Test Testerson',
-        title: 'Software Engineer',
+        job: {
+          title: 'Software Engineer',
+        },
         role: Role.User,
         value: 100,
         [valueSymbol]: 100_000,
@@ -78,7 +84,9 @@ describe('shape()', () => {
     expect(
       fn({
         name: 'Test Testerson',
-        title: 'Senior Software Engineer',
+        job: {
+          title: 'Senior Software Engineer',
+        },
         role: Role.User,
         value: 100,
         [valueSymbol]: 100_000,
@@ -91,4 +99,26 @@ describe('shape()', () => {
       }),
     ).toBeTruthy();
   });
+
+  it('Can check for additional properties', () => {
+    const fn = shape(
+      {
+        name: isString,
+      },
+      false,
+    );
+
+    expect(
+      fn({
+        name: 'Test Testerson',
+      }),
+    ).toBeTruthy();
+
+    expect(
+      fn({
+        name: 'Test Testerson',
+        extra: 'not allowed',
+      }),
+    ).toBeFalsy();
+  });
 });