You can test the computer to see if it fires the injectors, but doing any real testing requires a machine that cleans and flow tests them at the same time.
Having said that, here are some tips...
A Noid light available from Autozone, is one way to test the injector wiring.
I like to use an old injector with compressed air applied to the injector where the fuel rail would normally connect. I hook the whole thing up, apply compressed air to the injector and stick it in a paper cup of soapy water. When the engine cranks with the ignition switch on, if the injector fires, it makes bubbles. Cheap if you have the stuff laying around, and works good too.
There are two 10 pin connectors at the back of the upper manifold, one of them has all 8 injector connections. Pull them apart and check for damage. Each injector should ohm out at about 13 ohms +\- 1.5 ohms.
Remember that the computer supplies a ground path for the injectors. The power for the injectors comes through the ECC relay located on top of the computer. They have power to them any time the ignition is on. The computer turns on the ground and completes the circuit, making the injectors fire.
Their is nothing wrong with the computer or harness. I bought these injectiors used and I just wan to test them before I install them. What voltage energizes the injector coil?