Ruby 名称错误 - 未初始化的常量
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Ruby Name Error - Uninitialized constant
提问by septerr
I am doing exercisesand am
getting NameError:Unitialized Constant MyUnitTests::Roomwhen running test_ex47.rb.
我正在做练习并且NameError:Unitialized Constant MyUnitTests::Room在运行 test_ex47.rb时得到了。
test_ex47.rb:
test_ex47.rb:
require 'test/unit'
require_relative '../lib/ex47'
class MyUnitTests < Test::Unit::TestCase
def test_room()
gold = Room.new("Gold Room", """This room has gold in it you can grab. There's a doo to the north.""")
assert_equal(gold.name, "GoldRoom")
assert_equal(gold.paths, {})
end
def test_room_paths()
center = Room.new("Center", "Test room in the center.")
north = Room.new("North", "Test room in the north.")
south = Room.new("South", "Test room in the south.")
center.add_paths({:north => north, :south => south})
assert_equal(center.go(:north), north)
assert_equal(center.go(:south), south)
end
def test_map()
start = Room.new("Start", "You can go west and down a hole.")
west = Room.new("Trees", "There are trees here, you can go east.")
down = Room.new("Dungeon", "It's dark down here, you can go up.")
start.add_paths({:west => west, :down => down})
west.add_paths({:east => start})
down.add_paths({:up => start})
assert_equal(start.go(:west), west)
assert_equal(start.go(:west).go(:east), start)
assert_equal(start.go(down).go(up), start)
end
end
ex47.rb is located in the lib folder and looks like:
ex47.rb 位于 lib 文件夹中，如下所示：
class Room
aatr_accessor :name, :description, :paths
def initialize(name, description)
@name = name
@description = description
@paths = {}
end
def go(direction)
@paths[direction]
end
def add_paths(paths)
@paths.update(paths)
end
end
Error:
错误：
Finished tests in 0.000872s, 3440.3670 tests/s, 0.0000 assertions/s.
1) Error:
test_map(MyUnitTests):
NameError: uninitialized constant MyUnitTests::Room
test_ex47.rb:22:in `test_map'
2) Error:
test_room(MyUnitTests):
NameError: uninitialized constant MyUnitTests::Room
test_ex47.rb:6:in `test_room'
3) Error:
test_room_paths(MyUnitTests):
NameError: uninitialized constant MyUnitTests::Room
test_ex47.rb:12:in `test_room_paths'
3 tests, 0 assertions, 0 failures, 3 errors, 0 skips]
回答by Samwhoo
The problem here is that you are creating a Room object inside the MyUnitTests class on line 3. Ruby thinks you want to use a class called MyUnitTest::Room, which doesn't exist. You need to use an absolute class reference, like so:
这里的问题是您在第 3 行的 MyUnitTests 类中创建了一个 Room 对象。Ruby 认为您想使用一个名为 MyUnitTest::Room 的类，但它并不存在。您需要使用绝对类引用，如下所示：
class MyUnitTests < Test::Unit::TestCase
def test_room()
gold = ::Room.new("Gold Room", """This room has gold in it you can grab. There's a doo to the north.""")
assert_equal(gold.name, "GoldRoom")
assert_equal(gold.paths, {})
end
Notice the :: before Room.new on line 3 there? That tells Ruby that you want to create a Room object from the top level name space :)
注意到第 3 行的 Room.new 之前的 :: 了吗？这告诉 Ruby 你想从顶级命名空间创建一个 Room 对象:)
I hope that answers your question.
我希望这能回答你的问题。
EDIT: You'll also need to change your other references to the Room class to ::Room. Sorry, I thought only the top one was a problem because of the indentation. A closer look reveals that the rest need the :: as well.
编辑：您还需要将对 Room 类的其他引用更改为 ::Room。抱歉，由于缩进，我认为只有顶部有问题。仔细观察就会发现，其余的也需要 ::。
