Must

add Object#must method to constrain its origin and conversions

Testing Methods

be : check whether object equals to the argument kind_of : check whether object is a kind of the argument coerced : check whether object can be coerced to the argument blank : check whether object is blank? exist : check whether object is not nil (NOTE: false is ok)

Logical Methods

not : logical NOT

Nop Methods

a : return self an : return self

These effect nothing but exist only for English grammar.

Basic Examples

# test its value exactly 1.must.be 1 # => 1

1,2,3].must.be [1,2,3

# => [1,2,3]

# exceptions 1.must.be [] # Must::Invalid exception 1.must.be([]) :ng # => :ng 1.must.be(1) :ng # => 1

# as default value name = params.must.not.be.blank{ “No name” }

# existing test 1.must.exist # => 1 nil.must.exist # Must::Invalid exception false.must.exist # => false

# test class : ensures that a class of the object is one of given arguments 1.must.be.kind_of(Integer) # => 1 1.must.be.kind_of(Integer, Array) # => 1

].must.be.kind_of(Integer, Array) # => [

1.must.be.kind_of(String, Array) # Must::Invalid: expected String/Array but got Fixnum

# coercing : looks like kind_of except converting its value if possible 1.must.be.coerced(Integer, String => proc{|val| val.to_i}) # => 1 “1”.must.be.coerced(Integer, String => proc{|val| val.to_i}) # => 1 “1”.must.be.coerced(Integer, String => :to_i) # => 1 (NOTE: inline Symbol means sending the method) “1”.must.be.coerced(Integer, Symbol, String => proc:to_i) # => :to_i (NOTE: use proc to return Symbol itself)

Actual Examples

normal code:

def set_reader(reader)
  if reader.is_a?(CSV::Reader)
    @reader = reader
  elsif file.is_a?(String)
    @reader = CSV::Reader.create(i)
  elsif file.is_a?(Pathname)
    @reader = CSV::Reader.create(reader.read)
  else
    raise 'invalid reader'
  end
end

refactor above code with must plugin

def set_reader(reader)
  @reader = reader.must.be.coerced(CSV::Reader, Pathname=>:read, String=>{|i| CSV::Reader.create(i)}) {raise 'invalid reader'}
end

Install

github.com/maiha/must

Author

maiha@wota.jp