Testing a software for boolean expression evaluation

I am testing a software that accept boolean function as an input and calculate the value of that function for all possible values of variable in the function. Thus, I need to test the software on so many boolean expressions (thousands of expression that cover as much as possible of the input sample space). I need a way to automate generating these boolean expressions such as I get unique and complete set of expressions to test the different software functionalities when I use them as an input to my software. Your help is appreciated.