From 31860438d4e49c5f41a83a44b78f5f4a4c7d795a Mon Sep 17 00:00:00 2001
From: Bart van den Ende <bartvandenende-wm@users.noreply.github.com>
Date: Tue, 1 Oct 2024 09:20:11 +0200
Subject: [PATCH 1/2] feat: Add support for new d.ts extension format when
 using TS moduleresolution 'bundler' or 'nodenext'

---
 apps/api-extractor/src/api/ExtractorConfig.ts |  7 +++--
 .../src/api/test/ExtractorConfig.test.ts      | 28 +++++++++++++++++++
 ...rtvandenende-wm-4899_2024-10-01-07-19.json | 10 +++++++
 3 files changed, 43 insertions(+), 2 deletions(-)
 create mode 100644 apps/api-extractor/src/api/test/ExtractorConfig.test.ts
 create mode 100644 common/changes/@rushstack/eslint-patch/bartvandenende-wm-4899_2024-10-01-07-19.json

diff --git a/apps/api-extractor/src/api/ExtractorConfig.ts b/apps/api-extractor/src/api/ExtractorConfig.ts
index 5f9a739c820..3bd42145232 100644
--- a/apps/api-extractor/src/api/ExtractorConfig.ts
+++ b/apps/api-extractor/src/api/ExtractorConfig.ts
@@ -257,8 +257,11 @@ export class ExtractorConfig {
     path.join(__dirname, '../schemas/api-extractor-defaults.json')
   );
 
-  /** Match all three flavors for type declaration files (.d.ts, .d.mts, .d.cts) */
-  private static readonly _declarationFileExtensionRegExp: RegExp = /\.d\.(c|m)?ts$/i;
+  /**
+   * Match all three flavors for type declaration files (.d.ts, .d.mts, .d.cts)
+   * including the new TS 5 bundle resolutions (.d.\{extension\}.ts, .d.\{extension\}.mts, .d.\{extension\}.cts)
+   **/
+  private static readonly _declarationFileExtensionRegExp: RegExp = /\.d(\.[a-z]+)?\.(c|m)?ts$/i;
 
   /** {@inheritDoc IConfigFile.projectFolder} */
   public readonly projectFolder: string;
diff --git a/apps/api-extractor/src/api/test/ExtractorConfig.test.ts b/apps/api-extractor/src/api/test/ExtractorConfig.test.ts
new file mode 100644
index 00000000000..fa821b5f890
--- /dev/null
+++ b/apps/api-extractor/src/api/test/ExtractorConfig.test.ts
@@ -0,0 +1,28 @@
+// Copyright (c) Microsoft Corporation. All rights reserved. Licensed under the MIT license.
+// See LICENSE in the project root for license information.
+
+import { ExtractorConfig } from '../ExtractorConfig';
+
+describe('ExtractorConfig', () => {
+  describe('hasDtsFileExtension', () => {
+    it.each([
+      ['test.ts', false],
+      ['test.cts', false],
+      ['test.mts', false],
+      ['test.d.ts', true],
+      ['test.d.mts', true],
+      ['test.d.cts', true],
+      ['test.css', false],
+      ['test.css.ts', false],
+      ['test.css.d.ts', true],
+      ['test.json', false],
+      ['test.json.ts', false],
+      ['test.d.css.ts', true],
+      ['test.json.d.ts', true],
+      ['test.d.json.ts', true]
+    ])('file "%s" has dts file extension equals "%s"', (file, expected) => {
+      const result = ExtractorConfig.hasDtsFileExtension(file);
+      expect(result).toEqual(expected);
+    });
+  });
+});
diff --git a/common/changes/@rushstack/eslint-patch/bartvandenende-wm-4899_2024-10-01-07-19.json b/common/changes/@rushstack/eslint-patch/bartvandenende-wm-4899_2024-10-01-07-19.json
new file mode 100644
index 00000000000..fdc04b30542
--- /dev/null
+++ b/common/changes/@rushstack/eslint-patch/bartvandenende-wm-4899_2024-10-01-07-19.json
@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@microsoft/api-extractor",
+      "comment": "Add support for new d.ts extension format when using TS moduleresolution 'bundler' or 'nodenext'",
+      "type": "patch"
+    }
+  ],
+  "packageName": "@microsoft/api-extractor"
+}
\ No newline at end of file

From b6c910eb4f323e34924a1c05f9eb2caee55353e7 Mon Sep 17 00:00:00 2001
From: Bart van den Ende <bartvandenende-wm@users.noreply.github.com>
Date: Tue, 1 Oct 2024 09:33:08 +0200
Subject: [PATCH 2/2] chore: improve ordering

---
 apps/api-extractor/src/api/test/ExtractorConfig.test.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/apps/api-extractor/src/api/test/ExtractorConfig.test.ts b/apps/api-extractor/src/api/test/ExtractorConfig.test.ts
index fa821b5f890..28b735289e4 100644
--- a/apps/api-extractor/src/api/test/ExtractorConfig.test.ts
+++ b/apps/api-extractor/src/api/test/ExtractorConfig.test.ts
@@ -15,9 +15,9 @@ describe('ExtractorConfig', () => {
       ['test.css', false],
       ['test.css.ts', false],
       ['test.css.d.ts', true],
+      ['test.d.css.ts', true],
       ['test.json', false],
       ['test.json.ts', false],
-      ['test.d.css.ts', true],
       ['test.json.d.ts', true],
       ['test.d.json.ts', true]
     ])('file "%s" has dts file extension equals "%s"', (file, expected) => {