What is the test for a judge to grant adjournment in a criminal case?

In Barrette v. The Queen, 1976 CanLII 180 (SCC), [1977] 2 S.C.R. 121, Pigeon J., writing for the majority of the court, stated at p. 125: It is true that a decision on an application for adjournment is in the judge’s discretion. It is, however, a judicial discretion so that his decision may be reviewed on appeal if it is based on reasons which are not well founded in law. This right of review is especially wide when the consequence of the exercise of discretion is that someone is deprived of his rights, whether in criminal or in civil proceedings. At a glance, I have found in the last few years no less than half a dozen judgments in civil proceedings where a decision depriving a litigant of an important right was reversed on account of insufficient reasons given. . . .This being so in civil proceedings, there is all the more reason to so regard a discretionary decision in criminal proceedings, the effect whereof is to deprive the accused of his right to obtain the assistance of counsel and to summon witnesses in his defence. . . .