Test your GFCI's Monthly
The GFCI outlets in your home should be checked monthly. The purpose of a GFCI is to protect you from electrical shock. They are usually in areas of the home where electrical current might come in contact with water, such as bathrooms, kitchens and outdoors.
A GFCI monitors the amount of current flowing from hot to neutral. If there is any imbalance, it trips the circuit, essentially cutting off the electricity for your safety.
To test your GFCI, push the reset button on the GFCI outlet to prepare for testing.
Plug a night light into the receptacle. The light should come on.
Push the test button. The light should turn off.
Push the reset button again. The light should come back on.
If the light didn't turn off when the test button was pushed then it is not providing you with adequate protection from an electrical shock and you should consult a licensed electrician.
You should always check the instructions for your particular GFCI to make sure that you are testing the unit properly.