This is a very thorough test. Good job. One thing I wonder about is that through this test the relative_peak_threshold is changed from 0 to 0.15 to the default 0.5. I imagine the threshold is changed so that the assert passes?

I sometimes read tests to help me script my own code. When reading this test I remain puzzled as to what is a good relative_peak_threshold value to set. I think we should avoid this.

When you do not use the default value, a small comment would help as to why this choice was made. 

Are we convinced 0.5 is the best default? Could we point to a table or a full comparison in some appendix or somewhere for people to see. Reproducing the many tests and simulations we have done for ISMRM but that are not in abstracts?