What assumptions are made in the theory of international trade for countries to benefit from it?

The theory of trade is based on the following assumptions

• The amount of labor and capital in two countries differ (difference in endowments)
• Technology is the same among countries (a long-term assumption)
• Assume two countries
• Assume two commodities e.g. cotton and coffee
• Assume labour is the only factor of production
• Assume that supply of labour is constant and fully employed
• Assume perfect mobility of factors of production within the country and immobile between countries
• No transport costs are involved
• Barter trade system exists
• Production of commodities is subject constant costs