The weight_syndrome_graph method of Decoder objects previously did not have an explicit test. This allowed a problem with the retworkx migration to remain undetected (see #565 ).
A test has now been added (as well as refactoring to make testing easier).
A change to the weight calculation method was also made to improve accuracy.
Summary
The weight_syndrome_graph method of Decoder objects previously did not have an explicit test. This allowed a problem with the retworkx migration to remain undetected (see #565 ).
Fixes #565