Fix #392 - Spark.isolate prints stack trace

Isolates would print a stack trace upon re-render
if their DOM nodes had been manually removed from
the DOM without called Spark.finalize.

packages/spark/spark.js

@@ -543,6 +543,19 @@ var pathForRange = function (r) {
 // `range` is a region of `document`. Modify it in-place so that it
 // matches the result of Spark.render(htmlFunc), preserving landmarks.
 Spark.renderToRange = function (range, htmlFunc) {
+  // `range` may be out-of-document and we don't check here.
+  // XXX should we?
+  //
+  // Explicit finalization of ranges (done within Spark or by a call to
+  // Spark.finalize) prevents us from being called in the first place.
+  // The newly rendered material will be checked to see if it's in the
+  // document by scheduleOnscreenSetUp's scheduled setup.
+  // However, if range is not valid, bail out now before running
+  // htmlFunc.
+  var startNode = range.firstNode();
+  if (! startNode || ! startNode.parentNode)
+    return;
+
   var renderer = new Spark._Renderer();
 
   // Call 'func' for each landmark in 'range'. Pass two arguments to

packages/spark/spark_tests.js

@@ -3821,4 +3821,31 @@ Tinytest.add("spark - legacy preserve names", function (test) {
   Meteor.flush();
 });
 
+Tinytest.add("spark - update defunct range", function (test) {
+  // Test that Spark doesn't freak out if it tries to update
+  // a LiveRange on nodes that have been taken out of the document.
+  //
+  // See https://github.com/meteor/meteor/issues/392.
+
+  var R = ReactiveVar("foo");
+
+  var div = OnscreenDiv(Spark.render(function () {
+    return "<p>" + Spark.isolate(function() {
+      return R.get();
+    }) + "</p>";
+  }));
+
+  test.equal(div.html(), "<p>foo</p>");
+  R.set("bar");
+  Meteor.flush();
+  test.equal(R.numListeners(), 1);
+  test.equal(div.html(), "<p>bar</p>");
+  test.equal(div.node().firstChild.nodeName, "P");
+  div.node().firstChild.innerHTML = '';
+  R.set("baz");
+  Meteor.flush(); // should throw no errors
+  // will be 1 if our isolate func was run.
+  test.equal(R.numListeners(), 0);
+});
+
 })();