1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
|
require 'spec_helper'
describe 'null object impersonating another type' do
class Point
attr_reader :x, :y
end
subject(:null) { impersonation_class.new }
let(:impersonation_class) do
Naught.build do |b|
b.impersonate Point
end
end
it 'matches the impersonated type' do
expect(null).to be_a Point
end
it 'responds to methods from the impersonated type' do
expect(null.x).to be_nil
expect(null.y).to be_nil
end
it 'does not respond to unknown methods' do
expect { null.foo }.to raise_error(NoMethodError)
end
end
describe 'traceable null object' do
subject(:trace_null) do
null_object_and_line.first
end
let(:null_object_and_line) do
obj, line = trace_null_class.new, __LINE__ # rubocop:disable ParallelAssignment
[obj, line]
end
let(:instantiation_line) { null_object_and_line.last }
let(:trace_null_class) do
Naught.build(&:traceable)
end
it 'remembers the file it was instantiated from' do
expect(trace_null.__file__).to eq(__FILE__)
end
it 'remembers the line it was instantiated from' do
expect(trace_null.__line__).to eq(instantiation_line)
end
def make_null
trace_null_class.get(:caller => caller(1))
end
it 'can accept custom backtrace info' do
obj, line = make_null, __LINE__ # rubocop:disable ParallelAssignment
expect(obj.__line__).to eq(line)
end
end
describe 'customized null object' do
subject(:custom_null) { custom_null_class.new }
let(:custom_null_class) do
Naught.build do |b|
b.define_explicit_conversions
def to_path
'/dev/null'
end
def to_s
'NOTHING TO SEE HERE'
end
end
end
it 'responds to custom-defined methods' do
expect(custom_null.to_path).to eq('/dev/null')
end
it 'allows generated methods to be overridden' do
expect(custom_null.to_s).to eq('NOTHING TO SEE HERE')
end
end
TestNull = Naught.build
describe 'a named null object class' do
it 'has named ancestor modules' do
expect(TestNull.ancestors[0..2].collect(&:name)).to eq([
'TestNull',
'TestNull::Customizations',
'TestNull::GeneratedMethods',
])
end
end
|
