diff --git a/tests/unit/30_core_1.bats b/tests/unit/30_core_1.bats
index 3811b8a1c..dad84f1ab 100644
--- a/tests/unit/30_core_1.bats
+++ b/tests/unit/30_core_1.bats
@@ -186,3 +186,42 @@ EOF
   echo "status: $status"
   assert_output "3001/udp 3000/tcp 3003"
 }
+
+@test "(core) image type detection (herokuish default user)" {
+  export DOKKU_ROOT
+  deploy_app
+  source "$PLUGIN_CORE_AVAILABLE_PATH/common/functions"
+  source "$PLUGIN_CORE_AVAILABLE_PATH/config/functions"
+
+  run is_image_herokuish_based "dokku/$TEST_APP" "$TEST_APP"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+}
+
+@test "(core) image type detection (herokuish custom user)" {
+  export DOKKU_ROOT
+  deploy_app
+  CID=$(< "$DOKKU_ROOT/$TEST_APP/CONTAINER.web.1")
+  docker commit --change "ENV USER postgres" "$CID" "dokku/${TEST_APP}:latest"
+  dokku config:set --no-restart "$TEST_APP" DOKKU_APP_USER=postgres
+  source "$PLUGIN_CORE_AVAILABLE_PATH/common/functions"
+  source "$PLUGIN_CORE_AVAILABLE_PATH/config/functions"
+
+  run is_image_herokuish_based "dokku/$TEST_APP" "$TEST_APP"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+}
+
+@test "(core) image type detection (dockerfile)" {
+  export DOKKU_ROOT
+  deploy_app dockerfile
+  source "$PLUGIN_CORE_AVAILABLE_PATH/common/functions"
+  source "$PLUGIN_CORE_AVAILABLE_PATH/config/functions"
+
+  run is_image_herokuish_based "dokku/$TEST_APP" "$TEST_APP"
+  echo "output: $output"
+  echo "status: $status"
+  assert_failure
+}
diff --git a/tests/unit/test_helper.bash b/tests/unit/test_helper.bash
index 7381ed9d1..71e002da1 100644
--- a/tests/unit/test_helper.bash
+++ b/tests/unit/test_helper.bash
@@ -2,6 +2,7 @@
 
 # constants
 DOKKU_ROOT=${DOKKU_ROOT:=~dokku}
+DOCKER_BIN=${DOCKER_BIN:="docker"}
 DOKKU_LIB_ROOT=${DOKKU_LIB_PATH:="/var/lib/dokku"}
 PLUGIN_PATH=${PLUGIN_PATH:="$DOKKU_LIB_ROOT/plugins"}
 PLUGIN_AVAILABLE_PATH=${PLUGIN_AVAILABLE_PATH:="$PLUGIN_PATH/available"}