What is the test for provocation to reduce a killing from murder to voluntary manslaughter?

Provocation, to the extent that it raises a reasonable doubt about either premeditation or deliberation, reduces murder from first to second degree. (People v. Thomas (1945) 25 Cal.2d 880, 903.)

Sufficient provocation may further reduce a killing from murder to voluntary manslaughter. In the context of this case, a killing is voluntary manslaughter, rather than murder, when it occurs upon a "sudden quarrel or heat of passion." ( 192, subd. (a).) Under such circumstances, the malice aforethought required for murder is negated. (People v. Carasi (2008) 44 Cal.4th 1263, 1306.) Voluntary manslaughter has two components: (1) the objective component, which is satisfied if the verbal or physical conduct of the victim would be sufficient to provoke an ordinary person of average disposition to act rashly or without due deliberation and reflection, and (2) the subjective component, which is satisfied if the killer is shown to have acted while under the actual influence of a strong passion induced by such provocation. (People v. Moye (2009) 47 Cal.4th 537, 549-550.)