From cac52fcf0269ffde248006577ec537c6d7b04792 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Leosvel=20P=C3=A9rez=20Espinosa?=
 <leosvel.perez.espinosa@gmail.com>
Date: Mon, 17 Feb 2025 17:05:07 +0100
Subject: [PATCH] fix(devkit): handle missing `include` and `exclude` in
 tsconfig options when updating tsconfig to support js

---
 .../update-ts-configs-to-js.spec.ts           | 90 +++++++++++++++++++
 .../src/generators/update-ts-configs-to-js.ts |  4 +-
 2 files changed, 92 insertions(+), 2 deletions(-)
 create mode 100644 packages/devkit/src/generators/update-ts-configs-to-js.spec.ts

diff --git a/packages/devkit/src/generators/update-ts-configs-to-js.spec.ts b/packages/devkit/src/generators/update-ts-configs-to-js.spec.ts
new file mode 100644
index 0000000000000..79db3af92b5ab
--- /dev/null
+++ b/packages/devkit/src/generators/update-ts-configs-to-js.spec.ts
@@ -0,0 +1,90 @@
+import type { Tree } from 'nx/src/generators/tree';
+import { updateTsConfigsToJs } from './update-ts-configs-to-js';
+import { createTreeWithEmptyWorkspace } from 'nx/src/generators/testing-utils/create-tree-with-empty-workspace';
+
+describe('updateTsConfigsToJs', () => {
+  let tree: Tree;
+
+  beforeEach(() => {
+    tree = createTreeWithEmptyWorkspace();
+  });
+
+  it('should set allowJs to true in tsconfig.json', () => {
+    tree.write('tsconfig.json', `{}`);
+    tree.write('tsconfig.lib.json', `{}`);
+
+    updateTsConfigsToJs(tree, { projectRoot: '.' });
+
+    expect(tree.read('tsconfig.json', 'utf-8')).toMatchInlineSnapshot(`
+      "{
+        "compilerOptions": {
+          "allowJs": true
+        }
+      }
+      "
+    `);
+  });
+
+  it.each`
+    tsconfig
+    ${'tsconfig.app.json'}
+    ${'tsconfig.lib.json'}
+  `(
+    'should add the relevant include and exclude to $tsconfig',
+    ({ tsconfig }) => {
+      tree.write('tsconfig.json', `{}`);
+      tree.write(
+        tsconfig,
+        JSON.stringify({
+          include: ['src/**/*.ts'],
+          exclude: ['src/**/*.spec.ts', 'src/**/*.test.ts'],
+        })
+      );
+
+      updateTsConfigsToJs(tree, { projectRoot: '.' });
+
+      expect(tree.read(tsconfig, 'utf-8')).toMatchInlineSnapshot(`
+        "{
+          "include": [
+            "src/**/*.ts",
+            "src/**/*.js"
+          ],
+          "exclude": [
+            "src/**/*.spec.ts",
+            "src/**/*.test.ts",
+            "src/**/*.spec.js",
+            "src/**/*.test.js"
+          ]
+        }
+        "
+      `);
+    }
+  );
+
+  it.each`
+    tsconfig
+    ${'tsconfig.app.json'}
+    ${'tsconfig.lib.json'}
+  `(
+    'should update $tsconfig with the relevant include and exclude when those properties are not defined',
+    ({ tsconfig }) => {
+      tree.write('tsconfig.json', `{}`);
+      tree.write(tsconfig, `{}`);
+
+      updateTsConfigsToJs(tree, { projectRoot: '.' });
+
+      expect(tree.read(tsconfig, 'utf-8')).toMatchInlineSnapshot(`
+        "{
+          "include": [
+            "src/**/*.js"
+          ],
+          "exclude": [
+            "src/**/*.spec.js",
+            "src/**/*.test.js"
+          ]
+        }
+        "
+      `);
+    }
+  );
+});
diff --git a/packages/devkit/src/generators/update-ts-configs-to-js.ts b/packages/devkit/src/generators/update-ts-configs-to-js.ts
index 310f592f78288..e89941459b0a8 100644
--- a/packages/devkit/src/generators/update-ts-configs-to-js.ts
+++ b/packages/devkit/src/generators/update-ts-configs-to-js.ts
@@ -31,9 +31,9 @@ export function updateTsConfigsToJs(
 
   if (updateConfigPath) {
     updateJson(tree, updateConfigPath, (json) => {
-      json.include = uniq([...json.include, 'src/**/*.js']);
+      json.include = uniq([...(json.include ?? []), 'src/**/*.js']);
       json.exclude = uniq([
-        ...json.exclude,
+        ...(json.exclude ?? []),
         'src/**/*.spec.js',
         'src/**/*.test.js',
       ]);