rspec.md

   1 ---
   2 title: RSpec
   3 category: Ruby
   4 ---
   5
   6 ### Invoking tests
   7
   8 ```sh
   9 rake -T spec      # List spec tasks
  10
  11 rake spec         # Run all
  12
  13 rake spec/models/mymodel_spec.rb
  14 rake spec/models/mymodel_spec.rb:27
  15 ```
  16
  17 ## Writing tests
  18
  19 ```rb
  20 describe "A User (in general)" do
  21   include UserSpecHelper
  22
  23   subject { Person.new }
  24
  25   let(:admin) { Person.new(role: :admin) }
  26
  27   context "setter methods" do
  28     it "should do this" do
  29       pending "some other thing"
  30
  31       expect(subject.name).to eq 'x'
  32     end
  33   end
  34 end
  35 ```
  36
  37 ### Before/after
  38
  39 ```rb
  40 before :each do
  41   # before all tests
  42 end
  43
  44 before do
  45   # before this suite
  46 end
  47
  48 after do
  49   # after this suite
  50 end
  51 ```
  52
  53 ### Subjects
  54
  55 ```rb
  56 subject { CheckingAccount.new }
  57 it { is_expected.to be_empty }
  58
  59 # also names: subject(:account) { ... }
  60 ```
  61
  62 ## Expectations
  63
  64 ```rb
  65 target.should eq 1
  66 target.should_not eq 1
  67
  68 expect(target).to eq 1
  69 expect(target).not_to eq 1
  70 ```
  71
  72 ### Numeric
  73
  74 ```rb
  75 expect(5).to be < 6
  76 expect(5).to == 5
  77 expect(5).to equal value
  78 expect(5).to be_between(1, 10)
  79 expect(5).to be_within(0.05).of value
  80 ```
  81
  82 ### Compound expectations
  83
  84 ```rb
  85 expect(1).to (be < 2).or be > 5
  86 ```
  87
  88 Use `or`/`and` to string multiple matchers together. See: [Compound expectations](https://relishapp.com/rspec/rspec-expectations/docs/compound-expectations)
  89
  90 ### Comparison
  91
  92 ```rb
  93 expect(x).to be value
  94 expect(x).to satisfy { |arg| ... }
  95 expect(x).to match /regexp/
  96 ```
  97
  98 ### Predicate
  99
 100 ```rb
 101 expect(x).to be_zero    # FixNum#zero?
 102 expect(x).to be_empty   # Array#empty?
 103 expect(x).to have_key   # Hash#has_key?
 104 ```
 105
 106 ### Objects
 107
 108 ```rb
 109 expect(obj).to be_an_instance_of MyClass
 110 expect(obj).to be_a_kind_of MyClass
 111 expect(obj).to respond_to :save!
 112 ```
 113
 114 ### Control flow
 115
 116 ```rb
 117 expect { user.save! }.to raise_error
 118 expect { user.save! }.to raise_error(ExceptionName, /msg/)
 119 expect { user.save! }.to throw :symbol
 120 ```
 121
 122 ### Enumerables/arrays
 123
 124 ```rb
 125 expect(list).to include(<object>)
 126
 127 expect(list).to have(1).things
 128 expect(list).to have_at_least(2).things
 129 expect(list).to have_at_most(3).things
 130
 131 expect(list).to have(2).errors_on(:field)
 132 ```
 133
 134 ### Change
 135
 136 ```rb
 137 expect { thing.approve! }.to \
 138   change(thing, :status)
 139   .from(Status::AWAITING_APPROVAL)
 140   .to(Status::APPROVED)
 141
 142 expect { thing.destroy }.to \
 143   change(Thing, :count)
 144   .by(-1)
 145 ```
 146
 147 ## Doubles
 148
 149 ```rb
 150 book = double('book')
 151 book = instance_double('Book', pages: 250)
 152 ```
 153
 154 ### Method stubs
 155
 156 ```rb
 157 allow(die).to receive(:roll)
 158 allow(die).to receive(:roll) { 3 }
 159 allow_any_instance_of(Die).to receive(:roll)
 160
 161 expect(die).to receive(:roll)
 162   .with(1)
 163   .with(1, true)
 164   .with(boolean)
 165   .with(anything)
 166   .with(any_args)
 167   .with(1, any_args)
 168   .with(no_args)
 169   .with(hash_including(a: 1))
 170   .with(hash_excluding(a: 1))
 171   .with(array_including(:a, :b))
 172   .with(array_excluding(:a, :b))
 173   .with(instance_of(Fixnum))
 174   .with(kind_of(Numeric))
 175   .with(<matcher>)
 176
 177   .once
 178   .twice
 179   .exactly(n).times
 180   .at_least(:once)
 181   .at_least(:twice)
 182   .at_least(n).times
 183   .at_most(:once)
 184   .at_most(:twice)
 185   .at_most(n).times
 186 ```
 187
 188 https://relishapp.com/rspec/rspec-mocks/docs
 189
 190 ## Spec helpers
 191
 192 ```rb
 193 module UserSpecHelper
 194   def valid_user_attributes
 195     { :email => "joe@bloggs.com",
 196       :username => "joebloggs",
 197       :password => "abcdefg"}
 198   end
 199 end
 200 ```
 201
 202 ```rb
 203 describe User do
 204   include UserSpecHelper
 205
 206   ...
 207 end
 208 ```