How to read programmatically TEST/SBWTCK pin state?

No.

teh TEST pin is a direct hardware switch that affects the digital port logic and cannot be read from the MSP. However, you may indirectly check it: turn one of the 4-wire GPIO pins into output and output 0, then read the input register whether it is 0. Then turn it into output high and read again. If output and input don't match in both occasions, then JTAG is active and the digital I/O won't reach the pin.
However, I'm not sure what happens when SBW is active and the TEST pin is used for SBWTCK rather than TEST functionality.