That has schmitt trigger inputs so can't be tested just digitally. A simple go/no go approach would be to test each gate using something like,
You would also need to connect the supply pins.
You'll have to test each gate separately and all unused inputs (6 of them - not 8) should be connected to positive or ground. Might be easier to setup the circuit at one end and use flying leads to each gate to test.
In my circuit, all of those input pins are connected to a 10k resistor, and the other end of the 10k resistors connected to ground. Then you can use a pair of jumper wires (one end of each jumper connected to Vcc) to test each gate (one at a time) with all four truth table options.