117 lines
2.9 KiB
Ruby
117 lines
2.9 KiB
Ruby
require File.expand_path(File.dirname(__FILE__) + '/neo')
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class AboutHashes < Neo::Koan
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def test_creating_hashes
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empty_hash = Hash.new
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assert_equal Hash, empty_hash.class
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assert_equal({}, empty_hash)
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assert_equal 0, empty_hash.size
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end
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def test_hash_literals
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hash = { :one => "uno", :two => "dos" }
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assert_equal 2, hash.size
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end
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def test_accessing_hashes
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hash = { :one => "uno", :two => "dos" }
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assert_equal "uno", hash[:one]
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assert_equal "dos", hash[:two]
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assert_equal nil, hash[:doesnt_exist]
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end
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def test_accessing_hashes_with_fetch
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hash = { :one => "uno" }
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assert_equal "uno", hash.fetch(:one)
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assert_raise(KeyError) do
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hash.fetch(:doesnt_exist)
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end
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# THINK ABOUT IT:
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#
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# Why might you want to use #fetch instead of #[] when accessing hash keys?
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end
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def test_changing_hashes
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hash = { :one => "uno", :two => "dos" }
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hash[:one] = "eins"
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expected = { :one => "eins", :two => "dos" }
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assert_equal expected, hash
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# Bonus Question: Why was "expected" broken out into a variable
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# rather than used as a literal?
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end
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def test_hash_is_unordered
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hash1 = { :one => "uno", :two => "dos" }
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hash2 = { :two => "dos", :one => "uno" }
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assert_equal true, hash1 == hash2
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end
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def test_hash_keys
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hash = { :one => "uno", :two => "dos" }
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assert_equal 2, hash.keys.size
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assert_equal true, hash.keys.include?(:one)
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assert_equal true, hash.keys.include?(:two)
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assert_equal Array, hash.keys.class
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end
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def test_hash_values
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hash = { :one => "uno", :two => "dos" }
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assert_equal 2, hash.values.size
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assert_equal true, hash.values.include?("uno")
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assert_equal true, hash.values.include?("dos")
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assert_equal Array, hash.values.class
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end
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def test_combining_hashes
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hash = { "jim" => 53, "amy" => 20, "dan" => 23 }
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new_hash = hash.merge({ "jim" => 54, "jenny" => 26 })
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assert_equal true, hash != new_hash
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expected = { "jim" => 54, "amy" => 20, "dan" => 23, "jenny" => 26 }
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assert_equal true, expected == new_hash
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end
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def test_default_value
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hash1 = Hash.new
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hash1[:one] = 1
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assert_equal 1, hash1[:one]
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assert_equal nil, hash1[:two]
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hash2 = Hash.new("dos")
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hash2[:one] = 1
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assert_equal 1, hash2[:one]
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assert_equal "dos", hash2[:two]
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end
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def test_default_value_is_the_same_object
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hash = Hash.new([])
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hash[:one] << "uno"
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hash[:two] << "dos"
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assert_equal ["uno", "dos"], hash[:one]
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assert_equal ["uno", "dos"], hash[:two]
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assert_equal ["uno", "dos"], hash[:three]
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assert_equal true, hash[:one].object_id == hash[:two].object_id
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end
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def test_default_value_with_block
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hash = Hash.new {|hash, key| hash[key] = [] }
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hash[:one] << "uno"
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hash[:two] << "dos"
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assert_equal ["uno"], hash[:one]
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assert_equal ["dos"], hash[:two]
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assert_equal [], hash[:three]
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end
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end
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