diff --git a/packages/runtime-core/__tests__/rendererSuspense.spec.ts b/packages/runtime-core/__tests__/rendererSuspense.spec.ts
index 16953bee4..c5d2ad415 100644
--- a/packages/runtime-core/__tests__/rendererSuspense.spec.ts
+++ b/packages/runtime-core/__tests__/rendererSuspense.spec.ts
@@ -6,47 +6,50 @@ import {
   render,
   nodeOps,
   serializeInner,
-  nextTick
+  nextTick,
+  onMounted,
+  watch,
+  onUnmounted
 } from '@vue/runtime-test'
 
 describe('renderer: suspense', () => {
-  it('basic usage (nested + multiple deps)', async () => {
-    const msg = ref('hello')
-    const deps: Promise<any>[] = []
+  const deps: Promise<any>[] = []
 
-    const createAsyncComponent = (loader: () => Promise<ComponentOptions>) => ({
+  beforeEach(() => {
+    deps.length = 0
+  })
+
+  // a simple async factory for testing purposes only.
+  function createAsyncComponent<T extends ComponentOptions>(
+    comp: T,
+    delay: number = 0
+  ) {
+    return {
       async setup(props: any, { slots }: any) {
-        const p = loader()
+        const p: Promise<T> = new Promise(r => setTimeout(() => r(comp), delay))
         deps.push(p)
         const Inner = await p
         return () => h(Inner, props, slots)
       }
+    }
+  }
+
+  it('basic usage (nested + multiple deps)', async () => {
+    const msg = ref('hello')
+
+    const AsyncChild = createAsyncComponent({
+      setup(props: { msg: string }) {
+        return () => h('div', props.msg)
+      }
     })
 
-    const AsyncChild = createAsyncComponent(
-      () =>
-        new Promise(resolve => {
-          setTimeout(() => {
-            resolve({
-              setup(props: { msg: string }) {
-                return () => h('div', props.msg)
-              }
-            })
-          }, 0)
-        })
-    )
-
     const AsyncChild2 = createAsyncComponent(
-      () =>
-        new Promise(resolve => {
-          setTimeout(() => {
-            resolve({
-              setup(props: { msg: string }) {
-                return () => h('div', props.msg)
-              }
-            })
-          }, 10)
-        })
+      {
+        setup(props: { msg: string }) {
+          return () => h('div', props.msg)
+        }
+      },
+      10
     )
 
     const Mid = {
@@ -77,22 +80,11 @@ describe('renderer: suspense', () => {
   })
 
   test('fallback content', async () => {
-    const deps: Promise<any>[] = []
-
-    const Async = {
-      async setup() {
-        const p = new Promise(r => setTimeout(r, 1))
-        deps.push(p)
-        await p
-        // test resume for returning bindings
-        return {
-          msg: 'async'
-        }
-      },
-      render(this: any) {
-        return h('div', this.msg)
+    const Async = createAsyncComponent({
+      render() {
+        return h('div', 'async')
       }
-    }
+    })
 
     const Comp = {
       setup() {
@@ -113,16 +105,112 @@ describe('renderer: suspense', () => {
     expect(serializeInner(root)).toBe(`<div>async</div>`)
   })
 
-  test.todo('buffer mounted/updated hooks & watch callbacks')
+  test('onResolve', async () => {
+    const Async = createAsyncComponent({
+      render() {
+        return h('div', 'async')
+      }
+    })
 
-  test.todo('onResolve')
+    const onResolve = jest.fn()
 
+    const Comp = {
+      setup() {
+        return () =>
+          h(
+            Suspense,
+            {
+              onResolve
+            },
+            {
+              default: h(Async),
+              fallback: h('div', 'fallback')
+            }
+          )
+      }
+    }
+
+    const root = nodeOps.createElement('div')
+    render(h(Comp), root)
+    expect(serializeInner(root)).toBe(`<div>fallback</div>`)
+    expect(onResolve).not.toHaveBeenCalled()
+
+    await Promise.all(deps)
+    await nextTick()
+    expect(serializeInner(root)).toBe(`<div>async</div>`)
+    expect(onResolve).toHaveBeenCalled()
+  })
+
+  test('buffer mounted/updated hooks & watch callbacks', async () => {
+    const deps: Promise<any>[] = []
+    const calls: string[] = []
+    const toggle = ref(true)
+
+    const Async = {
+      async setup() {
+        const p = new Promise(r => setTimeout(r, 1))
+        deps.push(p)
+
+        watch(() => {
+          calls.push('watch callback')
+        })
+
+        onMounted(() => {
+          calls.push('mounted')
+        })
+
+        onUnmounted(() => {
+          calls.push('unmounted')
+        })
+
+        await p
+        // test resume for returning bindings
+        return {
+          msg: 'async'
+        }
+      },
+      render(this: any) {
+        return h('div', this.msg)
+      }
+    }
+
+    const Comp = {
+      setup() {
+        return () =>
+          h(Suspense, null, {
+            default: toggle.value ? h(Async) : null,
+            fallback: h('div', 'fallback')
+          })
+      }
+    }
+
+    const root = nodeOps.createElement('div')
+    render(h(Comp), root)
+    expect(serializeInner(root)).toBe(`<div>fallback</div>`)
+    expect(calls).toEqual([])
+
+    await Promise.all(deps)
+    await nextTick()
+    expect(serializeInner(root)).toBe(`<div>async</div>`)
+    expect(calls).toEqual([`watch callback`, `mounted`])
+
+    // effects inside an already resolved suspense should happen at normal timing
+    toggle.value = false
+    await nextTick()
+    expect(serializeInner(root)).toBe(`<!---->`)
+    expect(calls).toEqual([`watch callback`, `mounted`, 'unmounted'])
+  })
+
+  // should receive updated props/slots when resolved
   test.todo('content update before suspense resolve')
 
+  // mount/unmount hooks should not even fire
   test.todo('unmount before suspense resolve')
 
   test.todo('nested suspense')
 
+  test.todo('new async dep after resolve should cause suspense to restart')
+
   test.todo('error handling')
 
   test.todo('portal inside suspense')