Add tests

tests/lib/switch-selectors.js

@@ -42,3 +42,33 @@ tape("test switchesSelectors", function(t) {
 
   t.end()
 })
+
+tape("test switchesSelectors when number of elements don't match", function(t) {
+  var newTempDoc = document.implementation.createHTMLDocument()
+  var originalTempDoc = document.implementation.createHTMLDocument()
+
+  // a div container is used because swapping the containers
+  // will generate a new element, so things get weird
+  // using "body" generates a lot of testling cruft that I don't
+  // want so let's avoid that
+  var container = originalTempDoc.createElement("div")
+  container.innerHTML = "<p>Original text</p><span>No change</span>"
+  originalTempDoc.body.appendChild(container)
+
+  var container2 = newTempDoc.createElement("div")
+  container2.innerHTML = "<p>New text</p><p>More new text</p><span>New span</span>"
+  newTempDoc.body.appendChild(container2)
+
+  var switchSelectorsFn = switchesSelectors.bind(pjax,
+    {}, // switches
+    {}, // switchesOptions
+    ["p"], // selectors,
+    newTempDoc, // fromEl
+    originalTempDoc, // toEl,
+    {} // options
+  )
+
+  t.throws(switchSelectorsFn, null, "error was thrown properly since number of elements don't match")
+
+  t.end()
+})