fix bug where core-based preact vdom injections wouldnt work

Author: arshaw

packages/core/src/content-inject/ContentInjector.ts

@@ -1,4 +1,4 @@
-import { createElement, ComponentChild, JSX, Ref } from '../preact.js'
+import { createElement, ComponentChild, JSX, Ref, isValidElement } from '../preact.js'
 import { CustomContentGenerator } from '../common/render-hook.js'
 import { BaseComponent, setRef } from '../vdom-util.js'
 import { guid } from '../util/misc.js'
@@ -63,8 +63,12 @@ export class ContentInjector<RenderProps> extends BaseComponent<ContentInjectorP
           attrs.dangerouslySetInnerHTML = { __html: customGeneratorRes.html }
         } else if (isObject && ('domNodes' in customGeneratorRes)) {
           queuedDomNodes = Array.prototype.slice.call(customGeneratorRes.domNodes)
-        } else if (!isObject && typeof customGeneratorRes !== 'function') {
-          // primitive value (like string or number)
+        } else if (
+          isObject
+            ? isValidElement(customGeneratorRes) // vdom node
+            : typeof customGeneratorRes !== 'function' // primitive value (like string or number)
+        ) {
+          // use in vdom
           innerContent = customGeneratorRes
         } else {
           // an exotic object for handleCustomRendering

tests/src/event-render/event-render-hooks.ts

@@ -11,6 +11,23 @@ describe('eventContent', () => {
     ],
   })
 
+  it('can inject vdom nodes', () => {
+    let calendar = initCalendar({
+      eventContent(info, createElement) {
+        return (
+          createElement('span', {}, [ // TODO: document how to use Fragment
+            createElement('b', {}, info.timeText),
+            createElement('i', {}, info.event.title),
+          ])
+        )
+      },
+    })
+    let dayGridWrapper = new DayGridViewWrapper(calendar).dayGrid
+    let eventEl = dayGridWrapper.getEventEls()[0]
+    expect(eventEl.querySelector('b').innerHTML).toBe('1a')
+    expect(eventEl.querySelector('i').innerHTML).toBe('my event')
+  })
+
   it('can inject html content', () => {
     let calendar = initCalendar({
       eventContent(info) {