Add a CI build for Node 20.

.github/workflows/ci.yml

@@ -15,8 +15,8 @@ jobs:
             OS: ubuntu-latest
           - NodeVersion: 18
             OS: ubuntu-latest
-          - NodeVersion: 16
-            OS: windows-latest
+          - NodeVersion: 20
+            OS: ubuntu-latest
           - NodeVersion: 18
             OS: windows-latest
     name: Node.js v${{ matrix.NodeVersion }} (${{ matrix.OS }})

common/changes/@microsoft/rush/node-20_2023-09-18-18-57.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@microsoft/rush",
+      "comment": "",
+      "type": "none"
+    }
+  ],
+  "packageName": "@microsoft/rush"
+}

common/changes/@rushstack/ts-command-line/node-20_2023-09-18-18-57.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@rushstack/ts-command-line",
+      "comment": "",
+      "type": "none"
+    }
+  ],
+  "packageName": "@rushstack/ts-command-line"
+}

libraries/rush-lib/src/cli/test/RushXCommandLine.test.ts

@@ -8,6 +8,7 @@ import { Utilities } from '../../utilities/Utilities';
 import { Rush } from '../../api/Rush';
 import { RushConfiguration } from '../../api/RushConfiguration';
 import { RushConfigurationProject } from '../../api/RushConfigurationProject';
+import { NodeJsCompatibility } from '../../logic/NodeJsCompatibility';
 
 import { RushXCommandLine } from '../RushXCommandLine';
 
@@ -74,6 +75,8 @@ describe(RushXCommandLine.name, () => {
 
     // Mock console log
     logMock = jest.spyOn(console, 'log');
+
+    jest.spyOn(NodeJsCompatibility, 'isLtsVersion', 'get').mockReturnValue(true);
   });
 
   afterEach(() => {

libraries/ts-command-line/src/test/CommandLineParameter.test.ts

@@ -366,9 +366,23 @@ describe(CommandLineParameter.name, () => {
       const args: string[] = ['hello-world'];
       process.env.ENV_COLOR = '[u';
 
-      await expect(
-        commandLineParser.executeWithoutErrorHandling(args)
-      ).rejects.toThrowErrorMatchingSnapshot();
+      // TODO: When Node 18 support is removed, switch this to use
+      // ```
+      // await expect(
+      //   commandLineParser.executeWithoutErrorHandling(args)
+      // ).rejects.toThrowErrorMatchingSnapshot();
+      // ```
+
+      let error: string | undefined;
+      try {
+        await commandLineParser.executeWithoutErrorHandling(args);
+      } catch (e) {
+        error = e.message;
+      }
+
+      expect(error).toMatch(
+        /^The \[u environment variable value looks like a JSON array but failed to parse: Unexpected token /
+      );
     });
 
     it('raises an error if env var value is json containing non-scalars', async () => {

rush.json

@@ -42,7 +42,8 @@
    * LTS schedule: https://nodejs.org/en/about/releases/
    * LTS versions: https://nodejs.org/en/download/releases/
    */
-  "nodeSupportedVersionRange": ">=16.13.0 <17.0.0 || >=18.15.0 <19.0.0",
+  "nodeSupportedVersionRange": ">=16.13.0 <17.0.0 || >=18.15.0 <19.0.0 || >=20.6.1 <21.0.0",
+  "suppressNodeLtsWarning": true, // TODO: Remove when Node 20 goes LTS
 
   /**
    * If the version check above fails, Rush will display a message showing the current