aboutsummaryrefslogtreecommitdiffstats
path: root/activesupport/lib/active_support/testing/assertions.rb
blob: 8c9ea2c0e8b0b1806933e8c109f4ea52dd5f451a (plain) (blame)
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
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
module ActiveSupport
  module Testing
    module Assertions
      UNTRACKED = Object.new # :nodoc:

      # Asserts that an expression is not truthy. Passes if <tt>object</tt> is
      # +nil+ or +false+. "Truthy" means "considered true in a conditional"
      # like <tt>if foo</tt>.
      #
      #   assert_not nil    # => true
      #   assert_not false  # => true
      #   assert_not 'foo'  # => Expected "foo" to be nil or false
      #
      # An error message can be specified.
      #
      #   assert_not foo, 'foo should be false'
      def assert_not(object, message = nil)
        message ||= "Expected #{mu_pp(object)} to be nil or false"
        assert !object, message
      end

      # Assertion that the block should not raise an exception.
      #
      # Passes if evaluated code in the yielded block raises no exception.
      #
      #   assert_nothing_raised do
      #     perform_service(param: 'no_exception')
      #   end
      def assert_nothing_raised
        yield
      end

      # Test numeric difference between the return value of an expression as a
      # result of what is evaluated in the yielded block.
      #
      #   assert_difference 'Article.count' do
      #     post :create, params: { article: {...} }
      #   end
      #
      # An arbitrary expression is passed in and evaluated.
      #
      #   assert_difference 'Article.last.comments(:reload).size' do
      #     post :create, params: { comment: {...} }
      #   end
      #
      # An arbitrary positive or negative difference can be specified.
      # The default is <tt>1</tt>.
      #
      #   assert_difference 'Article.count', -1 do
      #     post :delete, params: { id: ... }
      #   end
      #
      # An array of expressions can also be passed in and evaluated.
      #
      #   assert_difference [ 'Article.count', 'Post.count' ], 2 do
      #     post :create, params: { article: {...} }
      #   end
      #
      # A lambda or a list of lambdas can be passed in and evaluated:
      #
      #   assert_difference ->{ Article.count }, 2 do
      #     post :create, params: { article: {...} }
      #   end
      #
      #   assert_difference [->{ Article.count }, ->{ Post.count }], 2 do
      #     post :create, params: { article: {...} }
      #   end
      #
      # An error message can be specified.
      #
      #   assert_difference 'Article.count', -1, 'An Article should be destroyed' do
      #     post :delete, params: { id: ... }
      #   end
      def assert_difference(expression, difference = 1, message = nil, &block)
        expressions = Array(expression)

        exps = expressions.map { |e|
          e.respond_to?(:call) ? e : lambda { eval(e, block.binding) }
        }
        before = exps.map(&:call)

        retval = yield

        expressions.zip(exps).each_with_index do |(code, e), i|
          error  = "#{code.inspect} didn't change by #{difference}"
          error  = "#{message}.\n#{error}" if message
          assert_equal(before[i] + difference, e.call, error)
        end

        retval
      end

      # Assertion that the numeric result of evaluating an expression is not
      # changed before and after invoking the passed in block.
      #
      #   assert_no_difference 'Article.count' do
      #     post :create, params: { article: invalid_attributes }
      #   end
      #
      # An error message can be specified.
      #
      #   assert_no_difference 'Article.count', 'An Article should not be created' do
      #     post :create, params: { article: invalid_attributes }
      #   end
      def assert_no_difference(expression, message = nil, &block)
        assert_difference expression, 0, message, &block
      end

      # Assertion that the result of evaluating an expression is changed before
      # and after invoking the passed in block.
      #
      #   assert_changes 'Status.all_good?' do
      #     post :create, params: { status: { ok: false } }
      #   end
      #
      # You can pass the block as a string to be evaluated in the context of
      # the block. A lambda can be passed for the block as well.
      #
      #   assert_changes -> { Status.all_good? } do
      #     post :create, params: { status: { ok: false } }
      #   end
      #
      # The assertion is useful to test side effects. The passed block can be
      # anything that can be converted to string with #to_s.
      #
      #   assert_changes :@object do
      #     @object = 42
      #   end
      #
      # The keyword arguments :from and :to can be given to specify the
      # expected initial value and the expected value after the block was
      # executed.
      #
      #   assert_changes :@object, from: nil, to: :foo do
      #     @object = :foo
      #   end
      #
      # An error message can be specified.
      #
      #   assert_changes -> { Status.all_good? }, 'Expected the status to be bad' do
      #     post :create, params: { status: { incident: true } }
      #   end
      def assert_changes(expression, message = nil, from: UNTRACKED, to: UNTRACKED, &block)
        exp = expression.respond_to?(:call) ? expression : -> { eval(expression.to_s, block.binding) }

        before = exp.call
        retval = yield

        unless from == UNTRACKED
          error = "#{expression.inspect} isn't #{from.inspect}"
          error = "#{message}.\n#{error}" if message
          assert from === before, error
        end

        after = exp.call

        if to == UNTRACKED
          error = "#{expression.inspect} didn't changed"
          error = "#{message}.\n#{error}" if message
          assert_not_equal before, after, error
        else
          message = "#{expression.inspect} didn't change to #{to}"
          error = "#{message}.\n#{error}" if message
          assert to === after, error
        end

        retval
      end

      # Assertion that the result of evaluating an expression is changed before
      # and after invoking the passed in block.
      #
      #   assert_no_changes 'Status.all_good?' do
      #     post :create, params: { status: { ok: true } }
      #   end
      #
      # An error message can be specified.
      #
      #   assert_no_changes -> { Status.all_good? }, 'Expected the status to be good' do
      #     post :create, params: { status: { ok: false } }
      #   end
      def assert_no_changes(expression, message = nil, &block)
        exp = expression.respond_to?(:call) ? expression : -> { eval(expression.to_s, block.binding) }

        before = exp.call
        retval = yield
        after = exp.call

        error = "#{expression.inspect} did change to #{after}"
        error = "#{message}.\n#{error}" if message
        assert_equal before, after, error

        retval
      end
    end
  end
end