Ovulation can be tested for by a variety of methods. The reliability of the tests varies greatly. There are tests on the market such as those that look for salt crystals in the salvia, that are totally unreliable and their use is discouraged. Testing the elasticity of the mucous produced by the cervix can give some information to women who have practiced this a lot that they are around the time of ovulation, but this varies from woman to woman. Temperature charts and hormone testing are the best available measures of ovulation.
Temperature charts
Basal body temperature charts are probably the simplest method of confirming that ovulation has occurred. The hormone Progesterone is produced in the second half of the menstrual cycle after ovulation. Progesterone leads to an increase of body temperature by about 0.5 degrees Celsius. The temperature chart is obtained by graphing over the course of a month, your temperature taken first thing in the morning before you get out of bed. If ovulation has occurred you will usually see the temperature go up in the second half of your menstrual cycle. This is fine if you have a fairly regular menstrual cycle but is much more difficult if cycles are not predictable. One important shortcoming of this method of determining ovulation is that it can only be used retrospectively and is of little assistance in predicting when ovulation will occur. Hence it is not helpful in timing sex. Click here for a link to a printable version of basal body temperature chart (source: parenthood.com)
Hormone testing
There are two reliable hormone methods of predicting and confirming ovulation. They are often used in combination in fertility clinics.
The first involves testing for the hormone Luteinising Hormone (LH) which is elevated 24 to 48 hours prior to ovulation. It is most accurately measured by serial blood tests. LH can, also be reliably measured by a morning urine test. There are a number of commercially available test kits on the market available for purchase at pharmacists and supermarkets (Clearplan and Ovusticks being examples). Generally a line or spot on the test kit will change colour if LH is detected in elevated amounts. This is the only method that can be used to predict ovulation. When a surge is seen in your LH level you should have intercourse within the next 24 hours.
Testing for the hormone Progesterone is an extremely accurate means of proving that ovulation has occurred. It is more accurate than LH testing as sometimes the LH level can go up, but ovulation does not properly develop. A single blood test on days 20 to 23 of the cycle is required for those women with regular 28 to 30 day menstrual cycles. For those with longer cycles, a test done 7 days prior to the expected next menstrual period will usually confirm that ovulation has occurred. When there is an irregular menstrual cycle, serial Progesterone tests performed every 5 days can be used to see if ovulation has occurred.