Add Makefile for local testing (#327)

Makefile

@@ -0,0 +1,25 @@
+.PHONY: help
+help: ## Display this help.
+	@$(MAKE) help
+	@awk 'BEGIN {FS = ":.*##"; printf "\nUsage:\n  make \033[36m<target>\033[0m\n"} /^[a-zA-Z_0-9-]+:.*?##/ { printf "  \033[36m%-15s\033[0m %s\n", $$1, $$2 } /^##@/ { printf "\n\033[1m%s\033[0m\n", substr($$0, 5) } ' $(MAKEFILE_LIST)
+
+
+##@ Testing:
+
+.PHONY: clean-lingering-resources
+clean-lingering-resources:
+	@echo Cleanup potential leftovers…
+	@-kubectl delete csidrivers.storage.k8s.io csi.spiffe.io \
+		&>/dev/null || true
+	@-kubectl delete ns \
+		$$(kubectl get ns -o json | jq -r '.items[] | .metadata.name' | grep spire) \
+		&>/dev/null || true
+	@-kubectl delete validatingwebhookconfigurations.admissionregistration.k8s.io \
+		$$(kubectl get validatingwebhookconfigurations.admissionregistration.k8s.io -o json | jq -r '.items[] | .metadata.name' | grep spire) \
+		&>/dev/null || true
+
+.PHONY: test
+test: ## Run tests using Helm chart-testing (ensure to run on dedicated test cluster)
+	@echo Running tests…
+	@ct install --debug \
+		--charts charts/spire