It is told often that only compounds having a methyl ketone and corresponding alcohols show positive iodoform test.
I tried to sketch a mechanism to show that 1-phenyl-1-keto-but-2-ene also gives iodoform test. However I haven't found any source that confirms that 1-phenyl-1-keto-but-2-ene shows iodoform test. Please check if there is any mistake in the mechanism:
This mechanism is very similar to the classical iodoform reaction mechanism.