What is the test for reducing the class of first degree murder from murder to manslaughter?

"Where an intentional and unlawful killing occurs 'upon a sudden quarrel or heat of passion' ( 192, subd. (a)), the malice aforethought required for murder is negated, and the offense is reduced to voluntary manslaughtera lesser included offense of murder. [Citation.] Such heat of passion exists only where 'the killer's reason was actually obscured as the result of a strong passion aroused by a "provocation" sufficient to cause an " 'ordinary [person] of average disposition . . . to act rashly or without due deliberation and reflection, and from this passion rather than from judgment.' " ' [Citation.] To satisfy this test, the victim must taunt the defendant or otherwise initiate the provocation." (People v. Carasi (2008) 44 Cal.4th 1263, 1306.)

"In a related vein, the ' "existence of provocation which is not 'adequate' to reduce the class of the offense [from murder to manslaughter] may nevertheless raise a reasonable doubt that the defendant formed the intent to kill upon, and carried it out after, deliberation and premeditation" 'an inquiry relevant to determining whether the offense is premeditated murder in the first degree, or unpremeditated murder in the second degree. [Citations.] First degree willful, deliberate, and premeditated murder involves a cold, calculated judgment, including one arrived at quickly [citation], and is evidenced by planning activity, a motive to kill, or an exacting manner of death. [Citation.] Such state of mind 'is manifestly inconsistent with having acted under the heat of passion-even if that state of mind was achieved after a considerable period of provocatory conduct.' " (People v. Carasi, supra, 44 Cal.4th at p. 1306.)

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"The test of whether provocation or heat of passion can negate malice so as to mitigate murder to voluntary manslaughter is objective. . . . 'The test of whether provocation or heat of passion can negate deliberation and premeditation so as to reduce first degree murder to second degree murder, on the other hand, is subjective. [Citations.]' 'If this were not so, the provocation would be a defense to murder and would be sufficient to reduce the crime to manslaughter.' " (People v. Padilla (2002) 103 Cal.App.4th 675, 678.)