This hasn't gotten attention in the way that the TPP and other trade agreements have gotten, nonetheless, there has indeed been a negotiation of a trade pact in Africa.
African nations sign largest free trade agreement since WTO
Of course, as with any trade pact, there are holdouts. Nigeria (having one of the largest economies on the continent) is being heavily criticized for being one of them. Perhaps they holdout because the pact is seen to favor small to medium-sized businesses and Nigeria's corporate conglomerates (they have more than any other country in Africa) don't stand to benefit directly.
Having said that, it seems somewhat bizarre that any African country would forgo the opportunity to trim and/or eliminate high tariffs between African countries when African states currently pay higher tariffs to export between other African countries than they do to export outside of the continent.
Again, though, Nigeria and likely, South Africa (another holdout), with their large number of multinationals probably saw no problem with this arrangement as it was unlikely to affect them directly. Still, that doesn't say much for their sense of unity and prosperity throughout the continent or their sense of forward-thinking in terms of the indirect benefits that they could get from their neighbors having more stable economies.