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Contents
require "insist/namespace"
require "insist/assert"
module Insist::Predicates
include Insist::Assert
PREDICATE_METHOD_RE = /\?$/
# Fails if the value does not respond to a method.
#
# insist { "hurray" }.respond_to?(:size)
def respond_to?(method)
assert(value.respond_to?(method),
"#{value.class} does not respond to the '#{method}' method")
end # def respond_to?
# Fails if the value.is_a?(klass) returns false.
#
# insist { "hurray" }.is_a?(Number)
def is_a?(klass)
assert(value.is_a?(klass), "#{value.class} is not a #{klass}")
end
# Pass through any 'foo?' style method calls to the 'value'
# and fail if the the return is false.
def method_missing(m, *args)
# If this is a predicate method (ends in question mark)
# call it on the value and assert truthiness.
if PREDICATE_METHOD_RE.match(m.to_s)
insist { value }.respond_to?(m)
# call the method, like .empty?, result must be truthy.
result = value.send(m, *args)
assert(result,
"#{value.class}{#{value.inspect}}##{m}(#{args.join(",")}) " \
"expected to return a truthy value, but returned #{result}")
return result
else
return super(m, *args)
end
end # def method_missing
end # module Insist::Predicates
Version data entries
67 entries across 63 versions & 18 rubygems