Tidy up makefile rules for KUBEBUILDER_ASSETS

Author: mdbooth

Makefile

@@ -133,14 +133,15 @@ ifdef KUBEBUILDER_ASSETS_DIR
 	setup_envtest_extra_args += --bin-dir $(KUBEBUILDER_ASSETS_DIR)
 endif
 
+.PHONY: kubebuilder_assets
+kubebuilder_assets: $(SETUP_ENVTEST)
+	@echo Fetching assets for $(KUBEBUILDER_ENVTEST_KUBERNETES_VERSION)
+	$(eval KUBEBUILDER_ASSETS ?= $(shell $(SETUP_ENVTEST) use --use-env -p path $(setup_envtest_extra_args) $(KUBEBUILDER_ENVTEST_KUBERNETES_VERSION)))
+
 .PHONY: test
 TEST_PATHS ?= ./...
-test: $(SETUP_ENVTEST) ## Run tests
-	set -xeuf -o pipefail; \
-	if [ -z "$(KUBEBUILDER_ASSETS)" ]; then \
-		KUBEBUILDER_ASSETS=`$(SETUP_ENVTEST) use --use-env -p path $(setup_envtest_extra_args) $(KUBEBUILDER_ENVTEST_KUBERNETES_VERSION)`; \
-	fi; \
-	KUBEBUILDER_ASSETS="$$KUBEBUILDER_ASSETS" go test -v $(TEST_PATHS) $(TEST_ARGS)
+test: kubebuilder_assets
+	KUBEBUILDER_ASSETS="$(KUBEBUILDER_ASSETS)" go test -v $(TEST_PATHS) $(TEST_ARGS)
 
 E2E_TEMPLATES_DIR=test/e2e/data/infrastructure-openstack
 E2E_KUSTOMIZE_DIR=test/e2e/data/kustomize