feat(openTab): Make passing in a URL optional

- Defaults to about:blank

actions/open-tab/README.md

@@ -1,5 +1,5 @@
-# `openTab(browser, url, options)`
-Opens a url in a new tab and waits for it to fully load
+# `openTab(browser, url?, options?)`
+Opens new tab, optionally navigating to a URL and waiting for it to fully load
 
 ## Example
 ```js
@@ -22,7 +22,7 @@ run()
 
 ## Parameters
 * `browser` ([Browser](../../interface#browser-object))
-* `url` (string)
+* `url` (optional string)
 * `options = {}` (object)
   * `timeout` (number): Number of milliseconds to wait for the page to load
     before throwing an error
@@ -31,7 +31,9 @@ run()
 * `tab` ([Promise<Tab>](../../interface#tab-object))
 
 ## Details
-`openTab` waits until the page is fully loaded and has not made a network
-request for `500ms`. Note that WebSocket connections are ignored. By default,
-`openTab` will wait at most 5 seconds and then throw an error. Set a custom
-timeout by passing in the `timeout` option.
+When not given any arguments, `openTab` defaults to `about:blank`.
+
+When given a URL, `openTab` waits until the page is fully loaded and has not
+made a network request for `500ms`. Note that WebSocket connections are ignored.
+By default, `openTab` will wait at most 5 seconds and then throw an error. Set a
+custom timeout by passing in the `timeout` option.

actions/open-tab/index.js

@@ -5,7 +5,9 @@ export default async function ({puppeteer: {browser}}, url, options) {
   const page = await browser.newPage()
   const tab = makeTab(browser, page)
 
-  await (options ? navigate(tab, url, options) : navigate(tab, url))
+  if (url) {
+    await (options ? navigate(tab, url, options) : navigate(tab, url))
+  }
 
   return tab
 }

actions/open-tab/index.test.js

@@ -45,6 +45,15 @@ test('allowing the navigation timeout to be set', async (t) => {
   }
 })
 
+test('opening empty tabs', async (t) => {
+  const {browser} = t.context
+
+  const tab = await openTab(browser)
+  t.is((await browser.puppeteer.browser.pages()).length, 1)
+
+  t.is(tab.puppeteer.page.url(), 'about:blank')
+})
+
 test('collecting console messages', async (t) => {
   const {browser, directory} = t.context