errors/equality/comparison.rb

tests/_examples/errors/equality/comparison.rb in the metorex repository.

# Two exceptions are equal when they share a class, a message, and a
# backtrace, so a copy equals its original.

one = ArgumentError.new
puts (one == one).to_s
puts (one == one.dup).to_s

puts (RuntimeError.new == RuntimeError.new).to_s
puts (TypeError.new("message") == TypeError.new("message")).to_s

# A different class, message, or backtrace makes them unequal.
puts (RuntimeError.new("message") == TypeError.new("message")).to_s
puts (RuntimeError.new("message") == RuntimeError.new("other")).to_s

traced = RuntimeError.new("message")
traced.set_backtrace(["a.rb:1"])
untraced = RuntimeError.new("message")
puts (traced == untraced).to_s

matching = RuntimeError.new("message")
matching.set_backtrace(["a.rb:1"])
puts (traced == matching).to_s

# Anything that is not an exception is never equal.
puts (ArgumentError.new == "").to_s
puts (ArgumentError.new != RuntimeError.new).to_s

Output:

true
true
true
true
false
false
false
true
false
true