It was recently revealed that Israeli F-16 pilots were training against one or more MiG-29s, borrowed from an unnamed country, and operated by Israeli pilots. This sort of thing is useful for several reasons. First, several potential foes (Lebanon, Syria, Iran and Sudan) possess MiG-29s. So knowing more about how MiG-29s operate (by having Israeli pilots fly them), and perform in combat (by having Israeli F-16s conduct mock combat against them), is useful. This experience would be very useful if Israel ever carried out the long discussed (and allegedly planned) air strike on Iranian nuclear weapons research facilities.
The MiG-29 entered Russian service in 1983, as the answer to the American F-16. Some 1,600 MiG-29s have been produced so far, with about 900 of them exported. The 22 ton aircraft is roughly comparable to the F-16, but it depends a lot on which version of either aircraft you are talking about. Russia is making a lot of money upgrading MiG-29s. Not just adding new electronics, but also making the airframe more robust. The MiG-29 was originally rated at 2,500 total flight hours. At that time (early 80s), Russia expected MiG-29s to fly about a hundred or so hours a year. Russia is offering to spiff up the airframe so that the aircraft can fly up to 4,000 hours, with more life extensions upgrades promised (the F-16 is good for over 7,000 hours). This won't be easy, as the MiG-29 has a history of unreliability and premature breakdowns (both mechanical and electronic). Compared to Western aircraft, like the F-16, the MiG-29 is available for action about two thirds as much. While extending the life of the MiG-29 into the 2030s is theoretically possible, actually doing so will be real breakthrough in Russian aircraft capabilities. Some MiG-29 flaws may never be solved, like the engine producing too much visible smoke.
All things being equal, the MiG-29 should be the equal of a F-16 or F-15. But in all combat so far, the MiG-29s have had the inferior pilots, and have lost. The Israelis want to keep it that way.