feat: add maxProperties object sampler support

src/samplers/object.js

@@ -33,5 +33,31 @@ export function sampleObject(schema, options = {}, spec, context) {
     res[`${String(propertyName)}1`] = traverse(schema.additionalProperties, options, spec, {depth: depth + 1 }).value;
     res[`${String(propertyName)}2`] = traverse(schema.additionalProperties, options, spec, {depth: depth + 1 }).value;
   }
+
+  // Strictly enforce maxProperties constraint
+  if (schema && typeof schema.properties === 'object' && schema.maxProperties !== undefined && Object.keys(res).length > schema.maxProperties) {
+    let filteredResult = {};
+    let propertiesAdded = 0;
+
+    // Always include required properties first, if present
+    const requiredProperties = (Array.isArray(schema.required) ? schema.required : []);
+    requiredProperties.forEach(propName => {
+        if (res[propName] !== undefined) {
+            filteredResult[propName] = res[propName];
+            propertiesAdded++;
+        }
+    });
+
+    // Add other properties until maxProperties is reached
+    Object.keys(res).forEach(propName => {
+        if (propertiesAdded < schema.maxProperties && !filteredResult.hasOwnProperty(propName)) {
+            filteredResult[propName] = res[propName];
+            propertiesAdded++;
+        }
+    });
+
+    res = filteredResult;
+  }
+
   return res;
 }

test/unit/object.spec.js

@@ -182,5 +182,28 @@ describe('sampleObject', () => {
       fooId: 'fb4274c7-4fcd-4035-8958-a680548957ff',
       barId: '3c966637-4898-4972-9a9d-baefa6cd6c89'
     });
-  })
+  });
+
+  it('respects maxProperties by including no more than 2 properties in the sampled object', () => {
+    // Define a schema with four properties and a maxProperties limit of two
+    const schema = {
+      type: 'object',
+      properties: {
+        name: { type: 'string' },
+        email: { type: 'string', format: 'email' },
+        age: { type: 'integer', minimum: 0 },
+        phone: { type: 'string' }
+      },
+      required: ['name', 'email'], // 'name' and 'email' are required
+      maxProperties: 2
+    };
+
+    const result = sampleObject(schema);
+
+    expect(Object.keys(result).length).to.be.at.most(2);
+
+    // Assert that if 'name' and 'email' are required, they are included
+    expect(result).to.have.property('name');
+    expect(result).to.have.property('email');
+  });
 });