Abstract: A tool for testing tubing, well casing, pipe or other flow conductors including longitudinally spaced sealers or packers which can be expanded to isolate a portion of the tubing string for subjecting the isolated portion to test pressure supplied to the isolated portion through flow controllers which include a fluid diffuser which prevents direct impingement of the testing fluid onto the inside coating on the tubing, thus preserving the integrity of the coating. The spaced sealers are expanded by piston and cylinder assemblies constructed and arranged so that the tool does not move when in operation, that is, it does not change in length in order to compress the sealers. The tool includes a head enabling it to be utilized inside the tubing or above the tubing and a foot or lower end provided with a swab which precludes testing fluid from going "downhole" and contaminating the "mud", thereby enabling the same testing fluid to be continuously reused.