Fix a Time#- spec
Fix a Time#+ spec
Fix a Time#hash spec
Fix a Time#round spec
Fix a Time#dup spec
Fix Time.at specs
Fix a Time#_dump spec
Fix a sharing Time.{new,local,mktime,gm,utc} spec
Add a Time#- spec for String arguments
Add a Time#+ spec for String arguments
Add Numeric#step specs for String arguments
Fix Time#{+,-} and Numeric#step with float-corecible String