Improve coverage through coverage tests.
Improve coverage through coverage tests.

nickerso/libcellml,cellml/libcellml,hsorby/libcellml,hsorby/libcellml,cellml/libcellml,nickerso/libcellml,MichaelClerx/libcellml,cellml/libcellml,hsorby/libcellml,MichaelClerx/libcellml,nickerso/libcellml,nickerso/libcellml,hsorby/libcellml,cellml/libcellml,MichaelClerx/libcellml