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
|
Feature: `change` matcher
The `change` matcher is used to specify that a block of code changes some mutable state.
You can specify what will change using either of two forms:
* `expect { do_something }.to change(object, :attribute)`
* `expect { do_something }.to change { object.attribute }`
You can further qualify the change by chaining `from` and/or `to` or one of `by`, `by_at_most`,
`by_at_least`.
Background:
Given a file named "lib/counter.rb" with:
"""ruby
class Counter
class << self
def increment
@count ||= 0
@count += 1
end
def count
@count ||= 0
end
end
end
"""
@skip-when-ripper-unsupported
Scenario: Expect change
Given a file named "spec/example_spec.rb" with:
"""ruby
require "counter"
RSpec.describe Counter, "#increment" do
it "should increment the count" do
expect { Counter.increment }.to change { Counter.count }.from(0).to(1)
end
# deliberate failure
it "should increment the count by 2" do
expect { Counter.increment }.to change { Counter.count }.by(2)
end
end
"""
When I run `rspec spec/example_spec.rb`
Then the output should contain "1 failure"
Then the output should contain "expected `Counter.count` to have changed by 2, but was changed by 1"
@skip-when-ripper-unsupported
Scenario: Expect no change
Given a file named "spec/example_spec.rb" with:
"""ruby
require "counter"
RSpec.describe Counter, "#increment" do
it "should not increment the count by 1 (using not_to)" do
expect { Counter.increment }.not_to change { Counter.count }
end
it "should not increment the count by 1 (using to_not)" do
expect { Counter.increment }.to_not change { Counter.count }
end
end
"""
When I run `rspec spec/example_spec.rb`
Then the output should contain "2 failures"
Then the output should contain "expected `Counter.count` not to have changed, but did change from 1 to 2"
|
