test: add Drop to fuzz test, add drop test cases

Makefile

@@ -16,10 +16,12 @@ test-unit: ## Run unit tests with coverage
 test-mutation: ## Run mutation tests with gremlins
 	gremlins unleash
 
+FUZZ_TIME ?= 30
+
 test-fuzz: ## Run all fuzz tests for 30s each
 	@for func in $$(grep -r --include='*_test.go' -oh 'func Fuzz\w*' . | sed 's/func //'); do \
 		echo "Fuzzing $$func..."; \
-		go test ./... -fuzz="^$$func$$" -fuzztime=30s; \
+		go test ./... -fuzz="^$$func$$" -fuzztime=$(FUZZ_TIME)s; \
 	done
 
 test: test-unit test-mutation test-fuzz ## Run all tests