Abstract: In common with conventional testing tools for this purpose, the present tool incorporates a central mandrel carrying a pair of vertically spaced packers which are expandable by fluid pressure, which mandrel forms a longitudinal bore having an outlet communicating with the annular space between the packers. In contradistinction to the prior tools, the bow spring and slips suspending assembly of the prior tools has been eliminated. Instead, the packers themselves are relied on to suspend or fix the tool in the tubing. To achieve this end, a novel valve assembly has been provided to control the admittance and bleeding off of pressurized fluid into the annular space. The valve assembly is adapted to first admit pressurized fluid into the annular space to set the packers and pressure test the tubing wall between the packers at relatively high pressure, for example 5000 psi.