add new render test to check that empty style tag is not injected, sl…

…ightly change render body assignment to not inject empty style tag if twind isn't utilised.

render.ts

@@ -18,6 +18,7 @@ export function render(c: Context, Component: VNode) {
 
   try {
     const { html, css } = extract(htmlString)
+    console.log(css.length)
     const startIdxOfHeadContent = html.indexOf(HEAD_TAG)
     const endIdxOfHeadContent = html.indexOf(
       `${HEAD_TAG.at(0)}/${HEAD_TAG.slice(1)}`,
@@ -32,7 +33,7 @@ export function render(c: Context, Component: VNode) {
         : ''
     c.res.body = html.replace(
       headContent,
-      `${headContent}<style>${css}</style>`,
+      `${headContent}${css.length > 0 ? `<style>${css}</style>` : ''}`,
     )
   } catch (_err) {
     if (c.dev) {

test/render.test.tsx

@@ -38,3 +38,33 @@ Deno.test('render', async () => {
     'text/html; charset=utf-8',
   )
 })
+
+Deno.test('No empty style tag is injected if no twind styles are utilised.', async () => {
+  const app = new cheetah()
+
+  const { render } = new Renderer()
+
+  function NonStyled() {
+    return (
+      <h3 id='styled'>
+        non-styled <code>h3</code> component
+      </h3>
+    )
+  }
+
+  app.get('/a', (c) => render(c, <NonStyled />))
+
+  const a = await app.fetch(new Request('http://localhost/a'))
+
+  const tx = await a.text()
+
+  const document = new DOMParser().parseFromString(
+    tx,
+    'text/html',
+  )
+  assert(document)
+  assertEquals(
+    [...document.getElementsByTagName('style')].length,
+    0,
+  )
+})