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 ### Comparison
  83
  84 ```rb
  85 expect(x).to be value
  86 expect(x).to satisfy { |arg| ... }
  87 expect(x).to match /regexp/
  88 ```
  89
  90 ### Predicate
  91
  92 ```rb
  93 expect(x).to be_zero    # FixNum#zero?
  94 expect(x).to be_empty   # Array#empty?
  95 expect(x).to have_key   # Hash#has_key?
  96 ```
  97
  98 ### Objects
  99
 100 ```rb
 101 expect(obj).to be_an_instance_of MyClass
 102 expect(obj).to be_a_kind_of MyClass
 103 expect(obj).to respond_to :save!
 104 ```
 105
 106 ### Control flow
 107
 108 ```rb
 109 expect { user.save! }.to raise_error
 110 expect { user.save! }.to raise_error(ExceptionName, /msg/)
 111 expect { user.save! }.to throw :symbol
 112 ```
 113
 114 ### Enumerables/arrays
 115
 116 ```rb
 117 expect(list).to include(<object>)
 118
 119 expect(list).to have(1).things
 120 expect(list).to have_at_least(2).things
 121 expect(list).to have_at_most(3).things
 122
 123 expect(list).to have(2).errors_on(:field)
 124 ```
 125
 126 ### Change
 127
 128 ```rb
 129 expect { thing.approve! }.to \
 130   change(thing, :status)
 131   .from(Status::AWAITING_APPROVAL)
 132   .to(Status::APPROVED)
 133
 134 expect { thing.destroy }.to \
 135   change(Thing, :count)
 136   .by(-1)
 137 ```
 138
 139 ## Doubles
 140
 141 ```rb
 142 book = double('book')
 143 book = instance_double('Book', pages: 250)
 144 ```
 145
 146 ### Method stubs
 147
 148 ```rb
 149 allow(die).to receive(:roll)
 150 allow(die).to receive(:roll) { 3 }
 151 allow_any_instance_of(Die).to receive(:roll)
 152
 153 expect(die).to receive(:roll)
 154   .with(1)
 155   .with(1, true)
 156   .with(boolean)
 157   .with(anything)
 158   .with(any_args)
 159   .with(1, any_args)
 160   .with(no_args)
 161   .with(hash_including(a: 1))
 162   .with(hash_excluding(a: 1))
 163   .with(array_including(:a, :b))
 164   .with(array_excluding(:a, :b))
 165   .with(instance_of(Fixnum))
 166   .with(kind_of(Numeric))
 167   .with(<matcher>)
 168
 169   .once
 170   .twice
 171   .exactly(n).times
 172   .at_least(:once)
 173   .at_least(:twice)
 174   .at_least(n).times
 175   .at_most(:once)
 176   .at_most(:twice)
 177   .at_most(n).times
 178 ```
 179
 180 https://relishapp.com/rspec/rspec-mocks/docs
 181
 182 ## Spec helpers
 183
 184 ```rb
 185 module UserSpecHelper
 186   def valid_user_attributes
 187     { :email => "joe@bloggs.com",
 188       :username => "joebloggs",
 189       :password => "abcdefg"}
 190   end
 191 end
 192 ```
 193
 194 ```rb
 195 describe User do
 196   include UserSpecHelper
 197
 198   ...
 199 end
 200 ```