make CheckGradientExhaustive fail for topless layers

Without this commit, it is possible to mistakenly call
CheckGradientExhaustive on a layer with no top blobs (i.e., a loss
layer), causing the gradient check to silently succeed while doing
nothing. With this commit, doing so will cause the test to fail.

diff --git a/src/caffe/test/test_gradient_check_util.hpp b/src/caffe/test/test_gradient_check_util.hpp
index 6ef76e2..1975886 100644 (file)
--- a/src/caffe/test/test_gradient_check_util.hpp
+++ b/src/caffe/test/test_gradient_check_util.hpp
@@ -135,6 +135,7 @@ template <typename Dtype>
 void GradientChecker<Dtype>::CheckGradientExhaustive(Layer<Dtype>* layer,
     vector<Blob<Dtype>*>* bottom, vector<Blob<Dtype>*>* top, int check_bottom) {
   layer->SetUp(*bottom, top);
+  CHECK_GT(top->size(), 0) << "Exhaustive mode requires at least one top blob.";
   // LOG(ERROR) << "Exhaustive Mode.";
   for (int i = 0; i < top->size(); ++i) {
     // LOG(ERROR) << "Exhaustive: blob " << i << " size " << top[i]->count();