What is the test of reasonableness for a police officer to walk upon common grass in a side yard to investigate a loud party complaint?

[68 Cal.App.4th 45] " ' "[T]he test of reasonableness is dependent upon the totality of facts and circumstances involved in the context of each case [citations] and does not turn merely upon whether a physical trespass is manifested [citations]." ' " (People v. Thompson (1990) 221 Cal.App.3d 923, 942, 270 Cal.Rptr. 863.) Like the trial court, I cannot say, as a matter of law, that officers may not walk upon common grass in a side yard to investigate a "loud party" complaint.