DocumentClash document_clash =
   Autodesk.Navisworks.Api.Application.MainDocument.Clash
   as DocumentClash;

DocumentClash document_clash2 =
   Autodesk.Navisworks.Api.Application.MainDocument.GetClash();

void ClashIterateResults()
{
   DocumentClash document_clash =
      Autodesk.Navisworks.Api.Application.MainDocument.GetClash();

   foreach (ClashTest test in document_clash.TestsData.Tests)
   {
      RecurseChildren(test);
   }
}

// GroupItem is a base-class of ClashTest.  If we needed to access
// the test's properties, we could declare "group" as that ClashTest
// but then would not be able to use this method to recurse further into
// unrelated type ClashResultGroup and would need to write a
// separate method.
public static void RecurseChildren(GroupItem group)
{
   foreach (SavedItem child in group.Children)
   {
      /* If we only wanted to access first-level children
       * without reference to whether they were groups or results
       * then we could:
       *
       * // access groups and results via shared interface
       * IClashResult result = child as IClashResult;
       * 
       * operate on that and not recurse further. */

      // GroupItem is the base-class of ClashResultGroup which defines
      // group-like behaviour, if we needed to access ay ClashResultGroup properties
      // we could cast to that equivalently... 
      GroupItem child_group = child as GroupItem;

      // is this a group?
      if (child_group != null)
      {
         // operate on the group's children
         RecurseChildren(child_group);
      }
      else
      {
         // Not a group, so must be a result.
         ClashResult result = child as ClashResult;

         // act on result...
      }
   }
}

DocumentClash document_clash =
   Autodesk.Navisworks.Api.Application.MainDocument.GetClash();

// get an existing test
ClashTest test = document_clash.TestsData.Tests[0] as ClashTest;

// test read from document-part is read-only, create a copy
ClashTest new_test = test.CreateCopyWithoutChildren() as ClashTest;

// set up some selection settings for our test
ClashSelection sel_a = new ClashSelection();
ClashSelection sel_b = new ClashSelection();

// simplest case, put everything into SelectionA, test that against itself
// and clear SelectionB
sel_a.SelfIntersect = true;
sel_a.Selection.SelectAll();
sel_a.PrimitiveTypes = PrimitiveTypes.Triangles;
sel_b.SelfIntersect = false;
sel_b.Selection.Clear();

new_test.SelectionA.CopyFrom(sel_a);
new_test.SelectionB.CopyFrom(sel_b);

// let's also change the test-type
new_test.TestType = ClashTestType.Clearance;
// we'll need a tolerance for that, this is in the model-units of the loaded model
// (NOT the display-units)
new_test.Tolerance = 0.1;

// Now edit the test stored in the document using properties from our changed
// copy.  Note that _Edit_ sets properties on only the test and does not touch
// any child-results.  Edit is thus far more efficient for changing only one point
// in the hierarchy when there are many children.
document_clash.TestsData.TestsEditTestFromCopy(test, new_test);

DocumentClash document_clash =
   Autodesk.Navisworks.Api.Application.MainDocument.GetClash();

// get an existing test
ClashTest test = document_clash.TestsData.Tests[test_index] as ClashTest;

// test read from document-part is read-only, create a copy
ClashTest new_test = test.CreateCopy() as ClashTest;

// edit the properties, results and result-groups of the new_test

// Now replace the test stored in the document with the whole of
// our edited hierarchy.  This is efficient as a way of doing many
// edits in one operation.
document_clash.TestsData.TestsReplaceWithCopy(test_index, new_test);

DocumentClash document_clash =
   Autodesk.Navisworks.Api.Application.MainDocument.GetClash();

// get an existing test
ClashTest test = document_clash.TestsData.Tests[test_index] as ClashTest;
IClashResult result = test.Children[result_index] as IClashResult;

// Now edit the status of the result stored in the document.
// 
// Note that this method works the same on results or result-groups.
// In the latter case if the property is one derived from child-results,
// (see individual properties) it sets it on all child-results.  It is an error (for a result-group) to try and
// set a property derived from child-results when there are no children.
// 
// _Edit_ sets properties on only the result and does not touch
// any child-results.  Edit is thus far more efficient for changing only one point
// in the hierarchy when there are many children.
// 
// The paradigm used here is different from the "ReplaceEntireObject" approach of
// (for example) TestsEditTestFromCopy because of the complexity of treating
// groups and individual results correctly, and detecting all possible errors.
document_clash.TestsData.TestsEditResultStatus(result, ClashResultStatus.Approved);

DocumentClash document_clash =
   Autodesk.Navisworks.Api.Application.MainDocument.GetClash();

// get an existing test
ClashTest test = document_clash.TestsData.Tests[test_index] as ClashTest;

// run the test, repeats the run whether the test believes it is "Complete" or not
// new results may be added, existing "New" results marked "Active" and non-reproducible results removed.
document_clash.TestsData.TestsRunTest(test);