box-o-sand/RubyFun/koans/about_hashes.rb

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require File.expand_path(File.dirname(__FILE__) + '/edgecase')
class AboutHashes < EdgeCase::Koan
def test_creating_hashes
empty_hash = Hash.new
assert_equal __, empty_hash.class
assert_equal({}, empty_hash)
assert_equal __, empty_hash.size
end
def test_hash_literals
hash = { :one => "uno", :two => "dos" }
assert_equal __, hash.size
end
def test_accessing_hashes
hash = { :one => "uno", :two => "dos" }
assert_equal __, hash[:one]
assert_equal __, hash[:two]
assert_equal __, hash[:doesnt_exist]
end
def test_changing_hashes
hash = { :one => "uno", :two => "dos" }
hash[:one] = "eins"
expected = { :one => __, :two => "dos" }
assert_equal __, expected == hash
# Bonus Question: Why was "expected" broken out into a variable
# rather than used as a literal?
end
def test_hash_is_unordered
hash1 = { :one => "uno", :two => "dos" }
hash2 = { :two => "dos", :one => "uno" }
assert_equal __, hash1 == hash2
end
def test_hash_keys
hash = { :one => "uno", :two => "dos" }
assert_equal __, hash.keys.size
assert_equal __, hash.keys.include?(:one)
assert_equal __, hash.keys.include?(:two)
assert_equal __, hash.keys.class
end
def test_hash_values
hash = { :one => "uno", :two => "dos" }
assert_equal __, hash.values.size
assert_equal __, hash.values.include?("uno")
assert_equal __, hash.values.include?("dos")
assert_equal __, hash.values.class
end
def test_combining_hashes
hash = { "jim" => 53, "amy" => 20, "dan" => 23 }
new_hash = hash.merge({ "jim" => 54, "jenny" => 26 })
assert_equal __, hash != new_hash
expected = { "jim" => __, "amy" => 20, "dan" => 23, "jenny" => __ }
assert_equal __, expected == new_hash
end
end