What is the legal test for disclosing the name of an informant in a criminal case?

If an informant is a material witness in a criminal case, the prosecution must disclose his or her name or suffer dismissal of the charges against the defendant. (People v. Lawley (2002) 27 Cal.4th 102, 159.) "An informant is a material witness if there appears, from the evidence presented, a reasonable possibility that he or she could give evidence on the issue of guilt that might exonerate the defendant." (Ibid.) It is defendant's burden to adduce "'"'some evidence'"' on this score." (Ibid.) Appellant did not meet this standard.