void preProcess() { for (MockViewHolder vh : mViewHolders) { final int ind = mTestAdapter.mItems.indexOf(vh.mItem); assertEquals( "actual adapter position should match", ind, mAdapterHelper.applyPendingUpdatesToPosition(vh.mPosition)); } mAdapterHelper.preProcess(); for (int i = 0; i < mPreProcessClone.mItems.size(); i++) { TestAdapter.Item item = mPreProcessClone.mItems.get(i); final int preLayoutIndex = mPreLayoutItems.indexOf(item); final int endIndex = mTestAdapter.mItems.indexOf(item); if (preLayoutIndex != -1) { assertEquals( "find position offset should work properly for existing elements" + i + " at pre layout position " + preLayoutIndex + " and post layout position " + endIndex, endIndex, mAdapterHelper.findPositionOffset(preLayoutIndex)); } } // make sure visible view holders still have continuous positions final StringBuilder vhLogBuilder = new StringBuilder(); for (ViewHolder vh : mViewHolders) { vhLogBuilder.append("\n").append(vh.toString()); } if (mViewHolders.size() > 0) { final String vhLog = vhLogBuilder.toString(); final int start = mViewHolders.get(0).getLayoutPosition(); for (int i = 1; i < mViewHolders.size(); i++) { assertEquals( "view holder positions should be continious in pre-layout" + vhLog, start + i, mViewHolders.get(i).getLayoutPosition()); } } mAdapterHelper.consumePostponedUpdates(); // now assert these two adapters have identical data. mPreProcessClone.applyOps(mFirstPassUpdates, mTestAdapter); mPreProcessClone.applyOps(mSecondPassUpdates, mTestAdapter); assertAdaptersEqual(mTestAdapter, mPreProcessClone); }