What is the test for determining whether a contract is a contract of sale of gasoline?

The court found that the contract of distributorship was not a contract of sale of respondent's gasoline but that pursuant to the letter agreement for distributorship, numerous contracts of sale of gasoline were made. Where only one agreement is mentioned in a complaint sounding in contract and that agreement is in writing and is designated by both parties as the sole basis of their relationship, 'the trial court was called upon to construe the written agreement according to its terms.' Cash v. Blackett, 87 Cal.App.2d 233, 236, 196 P.2d 585, 587. Since there was no agreement between the parties at bar other than that for the distributorship, the construction of that instrument disposes of the issues.