add feedback from Momo

packages/aws-cdk-lib/region-info/lib/fact.ts

@@ -1,14 +1,16 @@
+import { AWS_REGIONS } from './aws-entities';
+
 /**
  * A database of regional information.
  */
 export class Fact {
   /**
    * @returns the list of names of AWS regions for which there is at least one registered fact. This
-   *          may not be an exhaustive list of all available AWS regions.
+   *          includes Regions defined in AWS_REGIONS plus custom defined regions.
    */
   public static get regions(): string[] {
     // Return by copy to ensure no modifications can be made to the undelying constant.
-    return Array.from(Object.keys(this.database));
+    return Array.from(AWS_REGIONS.concat(Object.keys(this.database)));
   }
 
   /**

packages/aws-cdk-lib/region-info/test/fact.test.ts

@@ -92,7 +92,7 @@ describe('register', () => {
 
   test('registering a fact with a new region adds the region', () => {
     // GIVEN
-    const region = 'us-unreleased-1';
+    const region = 'my-custom-region';
     const name = FactName.PARTITION;
     const value = 'nebraska';
 
@@ -101,7 +101,7 @@ describe('register', () => {
     expect(() => Fact.register({ region, name, value })).not.toThrowError();
 
     // THEN
-    expect(Fact.regions.includes('us-unreleased-1')).toBeTruthy();
+    expect(Fact.regions.includes('my-custom-region')).toBeTruthy();
     expect(Fact.find(region, name)).toBe('nebraska');
   });
 });