ctest --output-on-failure

appveyor.yml

@@ -15,4 +15,4 @@ before_build:
 build_script:
 - cmake --build . --config %CONFIGURATION%
 test_script:
-- ctest -V .
+- ctest --output-on-failure .

scripts/travis/cmake.sh

@@ -27,4 +27,4 @@ fi
 
 $CMAKE .
 $CMAKE --build .
-$CTEST -VV .
+$CTEST --output-on-failure .