Purchase of inventory cost $1000, Intial testing cost $25 Carriage inward $100 Rebate $50 What is cost of inventory?

Inventory cost includes all direct costs and the answer is+-=

All above costs are relevant cost, except for initial testing cost. Initial testing cost may be relevant if it is a quality assurance cost and it is directly proportional to the acquisition of the inventory i.e. if the procurement of inventory increases (in terms of quantity) subsequently the testing cost will be increased.

However, if initial testing is a one time cost and is not related to subsequent procurement, then it will be considered as a sunk cost and shall be charged as an indirect cost.

all expenses including except the testing cost 

From Historical Cost (Financial Accounting) it will include all costs associated to produce the inventory.  However looking at Management Accounting perspective initial testing cost can be disregarded as it is a sunk cost.

Calculating inventory cost doesn't include the testing cost.So the cost would be.

Inventory cost will be USD/-

testing cost will be included as well,asset definition include and cover this as well.$