Turbomachinery for oil and gas EPC projects are shop tested to minimize the plant start-up risks and assure a trouble-free operation. However the extent of testing of turbomachinery vary with each project, though the minimum requirements dictated by the international codes and standards shall be met. In fact testing activities for turbomachinery are expensive, and specifying additional tests on top of the minimum requirements; which are narrated in this paper for major turbomachinery, need to be technically and commercially justified. Defining the extent of testing depends on several key factors which are listed and illustrated in this article. The Owner; in collaboration with the Contractor, is responsible to approve the required tests for a certain equipment based on critical analysis and a trade-off between risk, cost and schedule. However manufacturers' testing capacities do not always meet the testing requirements, this needs to be considered when specifying tests, else a test bed upgrade is necessary if the Owner is ready to contribute to the cost. This article surfs through the topic of shop testing for turbomachinery presenting best practices and lessons learnt from recent oil & gas EPC projects.