I completely  disagree.  The current test is much easier to understand.  1024M is much easier to read - and matches what the input is.  

Using "-eq $((1024 * 1024 * 1024))" proves my point.  What if we change the default size to 2048M - then we have to update this test to be "-eq $((1024 * 1024 * 1024 *2))" - how is that readable?  How does that correlate to the input?  By human readable I mean I look at the input i.e. 2048 and then I look at the test and see 2048 - not some equation that I have to calculate to ensure that it is the value that I think it is.

I am keeping this test as is.