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Project: RSpec Expectations 2.10

Publisher: RSpec

operator matchers

RSpec provides a number of matchers that are based on Ruby's built-in
operators. These pretty much work like you expect. For example, each of these
pass:

7.should == 7
[1, 2, 3].should == [1, 2, 3]
"this is a string".should =~ /^this/
"this is a string".should_not =~ /^that/
String.should === "this is a string"

You can also use comparison operators combined with the "be" matcher like
this:

37.should be < 100
37.should be <= 38
37.should be >= 2
37.should be > 7

RSpec also provides a =~ matcher for arrays that disregards differences in
the ording between the actual and expected array. For example:

[1, 2, 3].should =~ [2, 3, 1] # pass
[:a, :c, :b].should =~ [:a, :c] # fail
Scenarios
  1. numeric operator matchers
  2. string operator matchers
  3. array operator matchers
numeric operator matchers
Given
a file named "numeric_operator_matchers_spec.rb" with: 
describe 18 do
  it { should == 18 }
  it { should be < 20 }
  it { should be > 15 }
  it { should be <= 19 }
  it { should be >= 17 }

  it { should_not == 28 }

  # deliberate failures
  it { should == 28 }
  it { should be < 15 }
  it { should be > 20 }
  it { should be <= 17 }
  it { should be >= 19 }

  it { should_not == 18 }
end
When
I run rspec numeric_operator_matchers_spec.rb
Then
the output should contain "12 examples, 6 failures"
And
the output should contain: 
     Failure/Error: it { should == 28 }
       expected: 28
            got: 18 (using ==)
And
the output should contain: 
     Failure/Error: it { should be < 15 }
       expected: < 15
            got:   18
And
the output should contain: 
     Failure/Error: it { should be > 20 }
       expected: > 20
            got:   18
And
the output should contain: 
     Failure/Error: it { should be <= 17 }
       expected: <= 17
            got:    18
And
the output should contain: 
     Failure/Error: it { should be >= 19 }
       expected: >= 19
            got:    18
And
the output should contain: 
     Failure/Error: it { should_not == 18 }
       expected not: == 18
                got:    18
string operator matchers
Given
a file named "string_operator_matchers_spec.rb" with: 
describe "Strawberry" do
  it { should == "Strawberry" }
  it { should be < "Tomato" }
  it { should be > "Apple" }
  it { should be <= "Turnip" }
  it { should be >= "Banana" }
  it { should =~ /berry/ }

  it { should_not == "Peach" }
  it { should_not =~ /apple/ }

  it "reports that it is a string using ===" do
    String.should === subject
  end

  # deliberate failures
  it { should == "Peach" }
  it { should be < "Cranberry" }
  it { should be > "Zuchini" }
  it { should be <= "Potato" }
  it { should be >= "Tomato" }
  it { should =~ /apple/ }

  it { should_not == "Strawberry" }
  it { should_not =~ /berry/ }

  it "fails a spec asserting that it is a symbol" do
    Symbol.should === subject
  end
end
When
I run rspec string_operator_matchers_spec.rb
Then
the output should contain "18 examples, 9 failures"
And
the output should contain: 
     Failure/Error: it { should == "Peach" }
       expected: "Peach"
            got: "Strawberry" (using ==)
And
the output should contain: 
     Failure/Error: it { should be < "Cranberry" }
       expected: < "Cranberry"
            got:   "Strawberry"
And
the output should contain: 
     Failure/Error: it { should be > "Zuchini" }
       expected: > "Zuchini"
            got:   "Strawberry"
And
the output should contain: 
     Failure/Error: it { should be <= "Potato" }
       expected: <= "Potato"
            got:    "Strawberry"
And
the output should contain: 
     Failure/Error: it { should be >= "Tomato" }
       expected: >= "Tomato"
            got:    "Strawberry"
And
the output should contain: 
     Failure/Error: it { should =~ /apple/ }
       expected: /apple/
            got: "Strawberry" (using =~)
And
the output should contain: 
     Failure/Error: it { should_not == "Strawberry" }
       expected not: == "Strawberry"
                got:    "Strawberry"
And
the output should contain: 
     Failure/Error: it { should_not =~ /berry/ }
       expected not: =~ /berry/
                got:    "Strawberry"
And
the output should contain: 
     Failure/Error: Symbol.should === subject
       expected: "Strawberry"
            got: Symbol (using ===)
array operator matchers
Given
a file named "array_operator_matchers_spec.rb" with: 
describe [1, 2, 3] do
  it { should == [1, 2, 3] }
  it { should_not == [1, 3, 2] }

  it { should =~ [1, 2, 3] }
  it { should =~ [1, 3, 2] }
  it { should =~ [2, 1, 3] }
  it { should =~ [2, 3, 1] }
  it { should =~ [3, 1, 2] }
  it { should =~ [3, 2, 1] }

  # deliberate failures
  it { should_not == [1, 2, 3] }
  it { should == [1, 3, 2] }
  it { should =~ [1, 2, 1] }
end
When
I run rspec array_operator_matchers_spec.rb
Then
the output should contain "11 examples, 3 failures"
And
the output should contain: 
     Failure/Error: it { should_not == [1, 2, 3] }
       expected not: == [1, 2, 3]
                got:    [1, 2, 3]
And
the output should contain: 
     Failure/Error: it { should == [1, 3, 2] }
       expected: [1, 3, 2]
            got: [1, 2, 3] (using ==)
And
the output should contain: 
     Failure/Error: it { should =~ [1, 2, 1] }
       expected collection contained:  [1, 1, 2]
       actual collection contained:    [1, 2, 3]
       the missing elements were:      [1]
       the extra elements were:        [3]

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