Add avifalphapremtest

diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 765880a..11d1173 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -75,6 +75,11 @@
     target_include_directories(avifallocationtest PRIVATE ${GTEST_INCLUDE_DIRS})
     add_test(NAME avifallocationtest COMMAND avifallocationtest)
 
+    add_executable(avifalphapremtest gtest/avifalphapremtest.cc)
+    target_link_libraries(avifalphapremtest aviftest_helpers ${GTEST_BOTH_LIBRARIES})
+    target_include_directories(avifalphapremtest PRIVATE ${GTEST_INCLUDE_DIRS})
+    add_test(NAME avifalphapremtest COMMAND avifalphapremtest)
+
     add_executable(avifchangesettingtest gtest/avifchangesettingtest.cc)
     target_link_libraries(avifchangesettingtest aviftest_helpers ${GTEST_BOTH_LIBRARIES})
     target_include_directories(avifchangesettingtest PRIVATE ${GTEST_INCLUDE_DIRS})