encode_test_driver: test for failure prior to encode

limits the amount of failure messages should e.g., a test file fail to
be opened

Change-Id: I0b30da0faa78cada23a226b577b3a48c74a896cd
diff --git a/test/encode_test_driver.cc b/test/encode_test_driver.cc
index be4ef9a..128436e 100644
--- a/test/encode_test_driver.cc
+++ b/test/encode_test_driver.cc
@@ -195,6 +195,7 @@
 
     video->Begin();
     encoder->InitEncoder(video);
+    ASSERT_FALSE(::testing::Test::HasFatalFailure());
 
     unsigned long dec_init_flags = 0;  // NOLINT
     // Use fragment decoder if encoder outputs partitions.