add lifecycle test

Author: rixo

packages/svelte-hmr-spec/test/lifecycle.spec.js

@@ -0,0 +1,61 @@
+const { page } = require('test-hmr/commands')
+
+describe('lifecycle', () => {
+  testHmr`
+    # onMount
+
+    ${function*() {
+      for (const fn of ['mounted', 'unmounted']) {
+        this[fn] = sinon.fake()
+        yield page.exposeFunction(fn, this[fn])
+      }
+    }}
+
+    --- App.svelte ---
+
+    <script>
+      import { onMount } from 'svelte'
+
+      onMount(() => {
+        mounted()
+        return () => {
+          unmounted()
+        }
+      })
+    </script>
+
+    ::0 foo
+    ::1 bar
+    ::2 baz
+
+    * * *
+
+    ::0::
+
+      foo
+
+      ${function*() {
+        expect(this.mounted).to.have.been.calledOnce
+        expect(this.unmounted).to.not.have.been.called
+      }}
+
+    ::1::
+
+      bar
+
+      ${function*() {
+        expect(this.mounted).to.have.been.calledTwice
+        expect(this.unmounted).to.have.been.calledOnce
+      }}
+      
+    ::2::
+
+      baz
+
+      ${function*() {
+        expect(this.mounted).to.have.been.calledThrice
+        expect(this.unmounted).to.have.been.calledTwice
+      }}
+      
+  `
+})