How can test a pregnancy?
If you mean how to see if you are pregnant, then you could do a home pregnancy test which you have to pee on and it measures your hCG which is a hormone only found in pregnant women. You can also go your local doctor and ask for a blood test. There are two tests from the doctors; Quantitative Blood Test - which measures you exact amount of hCG or the Qualitative Blood Test - which gives you a basic yes or no answer to whether you are pregnant or not.
Pregnancy tests are around 97-99% accurate, but with a home pregnancy test, be sure to do 2-3 just to make sure.