From 51ec1d3e1852c44eb55111d1e43ca289c612bbdd Mon Sep 17 00:00:00 2001
From: Michael Sambol <sambol.michael@gmail.com>
Date: Wed, 11 Oct 2023 17:30:02 -0600
Subject: [PATCH 1/8] chore(region-info): update fact not found error message

---
 packages/aws-cdk-lib/region-info/lib/fact.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/aws-cdk-lib/region-info/lib/fact.ts b/packages/aws-cdk-lib/region-info/lib/fact.ts
index 366141721c693..1fdf17251beae 100644
--- a/packages/aws-cdk-lib/region-info/lib/fact.ts
+++ b/packages/aws-cdk-lib/region-info/lib/fact.ts
@@ -37,7 +37,7 @@ export class Fact {
     const foundFact = this.find(region, name);
 
     if (!foundFact) {
-      throw new Error(`No fact ${name} could be found for region: ${region} and name: ${name}`);
+      throw new Error(`No fact ${name} could be found for region: ${region} and name: ${name}. Regions is a fixed list and defined in aws-entities.ts as AWS_REGIONS.`);
     }
 
     return foundFact;

From 877334c28e292a64c4319c4ac628677aedbd07c1 Mon Sep 17 00:00:00 2001
From: Michael Sambol <sambol.michael@gmail.com>
Date: Thu, 12 Oct 2023 12:00:01 -0600
Subject: [PATCH 2/8] Add feedback from Luca

---
 packages/aws-cdk-lib/region-info/lib/fact.ts      |  6 ++----
 .../aws-cdk-lib/region-info/test/fact.test.ts     | 15 +++++++++++++++
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/packages/aws-cdk-lib/region-info/lib/fact.ts b/packages/aws-cdk-lib/region-info/lib/fact.ts
index 1fdf17251beae..eb75040bf4e82 100644
--- a/packages/aws-cdk-lib/region-info/lib/fact.ts
+++ b/packages/aws-cdk-lib/region-info/lib/fact.ts
@@ -1,5 +1,3 @@
-import { AWS_REGIONS } from './aws-entities';
-
 /**
  * A database of regional information.
  */
@@ -10,7 +8,7 @@ export class Fact {
    */
   public static get regions(): string[] {
     // Return by copy to ensure no modifications can be made to the undelying constant.
-    return Array.from(AWS_REGIONS);
+    return Array.from(Object.keys(this.database));
   }
 
   /**
@@ -37,7 +35,7 @@ export class Fact {
     const foundFact = this.find(region, name);
 
     if (!foundFact) {
-      throw new Error(`No fact ${name} could be found for region: ${region} and name: ${name}. Regions is a fixed list and defined in aws-entities.ts as AWS_REGIONS.`);
+      throw new Error(`No fact ${name} could be found for region: ${region} and name: ${name}.`);
     }
 
     return foundFact;
diff --git a/packages/aws-cdk-lib/region-info/test/fact.test.ts b/packages/aws-cdk-lib/region-info/test/fact.test.ts
index b3e3bab7fdab7..2e403f37cf7aa 100644
--- a/packages/aws-cdk-lib/region-info/test/fact.test.ts
+++ b/packages/aws-cdk-lib/region-info/test/fact.test.ts
@@ -89,4 +89,19 @@ describe('register', () => {
     // Cleanup
     Fact.unregister(region, name);
   });
+
+  test('registering a fact with a new region adds the region', () => {
+    // GIVEN
+    const region = 'us-unreleased-1';
+    const name = FactName.PARTITION;
+    const value = 'nebraska';
+
+    // WHEN
+    expect(Fact.find(region, name)).not.toBe(value);
+    expect(() => Fact.register({ region, name, value })).not.toThrowError();
+
+    // THEN
+    expect(Fact.regions.includes('us-unreleased-1')).toBeTruthy();
+    expect(Fact.find(region, name)).toBe('nebraska');
+  });
 });

From f2164c916affa0486ae58b764845410160d42fd6 Mon Sep 17 00:00:00 2001
From: Michael Sambol <sambol.michael@gmail.com>
Date: Thu, 12 Oct 2023 13:02:27 -0600
Subject: [PATCH 3/8] Add int test

---
 .../region-info/test/region-info.test.ts         | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/packages/aws-cdk-lib/region-info/test/region-info.test.ts b/packages/aws-cdk-lib/region-info/test/region-info.test.ts
index f014405a8b145..5d195634e956c 100644
--- a/packages/aws-cdk-lib/region-info/test/region-info.test.ts
+++ b/packages/aws-cdk-lib/region-info/test/region-info.test.ts
@@ -1,5 +1,5 @@
 import { APPCONFIG_LAMBDA_LAYER_ARNS, CLOUDWATCH_LAMBDA_INSIGHTS_ARNS } from '../build-tools/fact-tables';
-import { FactName, RegionInfo } from '../lib';
+import { Fact, FactName, RegionInfo } from '../lib';
 import { AWS_REGIONS, AWS_SERVICES } from '../lib/aws-entities';
 
 test('built-in data is correct', () => {
@@ -66,10 +66,22 @@ test('limitedRegionMap only returns information for certain regions', () => {
   expect(map2['cn-north-1']).toBeDefined();
 });
 
+test('registering a fact with a new region adds the region', () => {
+  const region = 'us-unreleased-1';
+  const name = FactName.PARTITION;
+  const value = 'nebraska';
+
+  expect(Fact.find(region, name)).not.toBe(value);
+  expect(() => Fact.register({ region, name, value })).not.toThrowError();
+
+  expect(Fact.regions.includes('us-unreleased-1')).toBeTruthy();
+  expect(Fact.find(region, name)).toBe('nebraska');
+});
+
 test.each([
   ['us-east-1', false],
   ['me-south-1', true],
   ['us-iso-west-1', false],
 ])('%p should be opt-in: %p', (region, expected) => {
   expect(RegionInfo.get(region).isOptInRegion).toEqual(expected);
-});
\ No newline at end of file
+});

From a127b92350469a55fdeb64480bbc9c279dbaf4b8 Mon Sep 17 00:00:00 2001
From: Michael Sambol <sambol.michael@gmail.com>
Date: Thu, 12 Oct 2023 13:06:17 -0600
Subject: [PATCH 4/8] thats not actually an int test

---
 .../aws-cdk-lib/region-info/test/region-info.test.ts | 12 ------------
 1 file changed, 12 deletions(-)

diff --git a/packages/aws-cdk-lib/region-info/test/region-info.test.ts b/packages/aws-cdk-lib/region-info/test/region-info.test.ts
index 5d195634e956c..76819bc0baf79 100644
--- a/packages/aws-cdk-lib/region-info/test/region-info.test.ts
+++ b/packages/aws-cdk-lib/region-info/test/region-info.test.ts
@@ -66,18 +66,6 @@ test('limitedRegionMap only returns information for certain regions', () => {
   expect(map2['cn-north-1']).toBeDefined();
 });
 
-test('registering a fact with a new region adds the region', () => {
-  const region = 'us-unreleased-1';
-  const name = FactName.PARTITION;
-  const value = 'nebraska';
-
-  expect(Fact.find(region, name)).not.toBe(value);
-  expect(() => Fact.register({ region, name, value })).not.toThrowError();
-
-  expect(Fact.regions.includes('us-unreleased-1')).toBeTruthy();
-  expect(Fact.find(region, name)).toBe('nebraska');
-});
-
 test.each([
   ['us-east-1', false],
   ['me-south-1', true],

From 17654c3a4e62c332dee68fcae559363370970290 Mon Sep 17 00:00:00 2001
From: Michael Sambol <sambol.michael@gmail.com>
Date: Mon, 23 Oct 2023 18:58:29 -0600
Subject: [PATCH 5/8] add feedback from Momo

---
 packages/aws-cdk-lib/region-info/lib/fact.ts       | 6 ++++--
 packages/aws-cdk-lib/region-info/test/fact.test.ts | 4 ++--
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/packages/aws-cdk-lib/region-info/lib/fact.ts b/packages/aws-cdk-lib/region-info/lib/fact.ts
index eb75040bf4e82..38df4573f31db 100644
--- a/packages/aws-cdk-lib/region-info/lib/fact.ts
+++ b/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)));
   }
 
   /**
diff --git a/packages/aws-cdk-lib/region-info/test/fact.test.ts b/packages/aws-cdk-lib/region-info/test/fact.test.ts
index 2e403f37cf7aa..46abed8a371b6 100644
--- a/packages/aws-cdk-lib/region-info/test/fact.test.ts
+++ b/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');
   });
 });

From 04e22bf04842f4494326b141ec3f943465ed096e Mon Sep 17 00:00:00 2001
From: Michael Sambol <sambol.michael@gmail.com>
Date: Mon, 23 Oct 2023 18:59:24 -0600
Subject: [PATCH 6/8] capital R

---
 packages/aws-cdk-lib/region-info/lib/fact.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/aws-cdk-lib/region-info/lib/fact.ts b/packages/aws-cdk-lib/region-info/lib/fact.ts
index 38df4573f31db..9671de701a5c8 100644
--- a/packages/aws-cdk-lib/region-info/lib/fact.ts
+++ b/packages/aws-cdk-lib/region-info/lib/fact.ts
@@ -5,7 +5,7 @@ import { AWS_REGIONS } from './aws-entities';
  */
 export class Fact {
   /**
-   * @returns the list of names of AWS regions for which there is at least one registered fact. This
+   * @returns the list of names of AWS Regions for which there is at least one registered fact. This
    *          includes Regions defined in AWS_REGIONS plus custom defined regions.
    */
   public static get regions(): string[] {

From 714db32f0e2117a718ac2c067bbeea929f52fef3 Mon Sep 17 00:00:00 2001
From: Michael Sambol <sambol.michael@gmail.com>
Date: Mon, 23 Oct 2023 19:00:08 -0600
Subject: [PATCH 7/8] remove Fact

---
 packages/aws-cdk-lib/region-info/test/region-info.test.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/aws-cdk-lib/region-info/test/region-info.test.ts b/packages/aws-cdk-lib/region-info/test/region-info.test.ts
index 76819bc0baf79..76130465d6567 100644
--- a/packages/aws-cdk-lib/region-info/test/region-info.test.ts
+++ b/packages/aws-cdk-lib/region-info/test/region-info.test.ts
@@ -1,5 +1,5 @@
 import { APPCONFIG_LAMBDA_LAYER_ARNS, CLOUDWATCH_LAMBDA_INSIGHTS_ARNS } from '../build-tools/fact-tables';
-import { Fact, FactName, RegionInfo } from '../lib';
+import { FactName, RegionInfo } from '../lib';
 import { AWS_REGIONS, AWS_SERVICES } from '../lib/aws-entities';
 
 test('built-in data is correct', () => {

From b5b907aa6baee5a479d672a86abc5eba71d1319c Mon Sep 17 00:00:00 2001
From: Michael Sambol <sambol.michael@gmail.com>
Date: Mon, 23 Oct 2023 19:19:52 -0600
Subject: [PATCH 8/8] make sure regions are unique

---
 packages/aws-cdk-lib/region-info/lib/fact.ts       | 4 ++--
 packages/aws-cdk-lib/region-info/test/fact.test.ts | 4 ++++
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/packages/aws-cdk-lib/region-info/lib/fact.ts b/packages/aws-cdk-lib/region-info/lib/fact.ts
index 9671de701a5c8..67bbe9ce42d52 100644
--- a/packages/aws-cdk-lib/region-info/lib/fact.ts
+++ b/packages/aws-cdk-lib/region-info/lib/fact.ts
@@ -9,8 +9,8 @@ export class Fact {
    *          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(AWS_REGIONS.concat(Object.keys(this.database)));
+    // Return the union of regions in AWS_REGIONS and custom defined regions.
+    return [...new Set([...AWS_REGIONS, ...Object.keys(this.database)])];
   }
 
   /**
diff --git a/packages/aws-cdk-lib/region-info/test/fact.test.ts b/packages/aws-cdk-lib/region-info/test/fact.test.ts
index 46abed8a371b6..a77e34bade5d1 100644
--- a/packages/aws-cdk-lib/region-info/test/fact.test.ts
+++ b/packages/aws-cdk-lib/region-info/test/fact.test.ts
@@ -104,4 +104,8 @@ describe('register', () => {
     expect(Fact.regions.includes('my-custom-region')).toBeTruthy();
     expect(Fact.find(region, name)).toBe('nebraska');
   });
+
+  test('regions does not return duplicate regions', () => {
+    expect(new Set(Fact.regions).size == Fact.regions.length).toBeTruthy();
+  });
 });