Is aids test reliable ?

Lets say I give the female partner a test prior to having sex. If the test is clean, does that guarantee that the person did not catch it, say, a week ago. Does not aids virus hide for month before showing up. So does that mean that the test that shows clean does not mean she is clean since she may have gotten it a week ago if she had sex and I did not know about...and the machine did not pick it up.
Or aids has to be detected if it is going to transfer to another person and so if it is not detected from the week ago sex that it won't pass to another person...inother words it has to be a full blown aids before it passes to another person?

No it is not reliable. The test itself is not reliable, it says so on the form that you sign, read it, it says it on there. Also the test would not be reliable in the case of having contracted just before having gotten the test, I know that most viruses take a while to show up, HIV shoul be no different.

HIV antibodies will usually show up in tests within 3 months of the day the person gets infected, but in extremely rare cases, it can take up to 6 months for the antibodies to show up on tests. Tests are very reliable if done after the appropriate amount of time.
As soon as a person is infected with HIV, they are capable of infecting others. It does not have to be detectable in a person for the person to be able to transmit it. It does not have to be full-blown AIDS to be transmitted. (A person's diagnosis changes from HIV+ to full blown AIDS when their CD4 cell count drops to 200 or below.)
One problem with HIV is that because there are often no symptoms soon after infection, people may transmit HIV to others before they know that they themselves are infected, either because they were tested too soon, or because they were never tested.

HIV can take over a year to be detectable in some people, but usually is detectable in 3 months in most people...So keep worrying

Only if you took a swim in a pool that was closed.