fix: resolve #2827 — CDK8s+: Support headless services without ports

Fixes #2827

Signed-off-by: tudragon154203 <76395825+tudragon154203@users.noreply.github.com>

Author: tudragon154203

test/cdk8s-plus-XX/test.service.ts

@@ -0,0 +1,40 @@
+import { App, Chart, Service, Testing } from '../../src';
+
+describe('service', () => {
+ test('allows headless service without ports', () => {
+    const app = new App();
+    const chart = new Chart(app, 'test');
+
+    new Service(chart, 'Service', {
+      clusterIP: 'None',
+      selector: {
+        app: 'foo',
+      },
+    });
+
+    const manifests = Testing.synth(chart);
+    const service = manifests.find((m) => m.kind === 'Service') as any;
+
+    expect(service).toMatchObject({
+      spec: {
+        clusterIP: 'None',
+      },
+    });
+    expect(service.spec.ports ?? []).toEqual([]);
+ });
+
+ test('requires a port for non-headless services', () => {
+    const app = new App();
+    const chart = new Chart(app, 'test');
+
+    expect(() => {
+      new Service(chart, 'Service', {
+        selector: {
+          app: 'foo',
+        },
+      });
+
+      Testing.synth(chart);
+    }).toThrow(/port/i);
+ });
+});