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Project: RSpec Expectations 3.12

Publisher: RSpec

`throw_symbol` matcher

The throw_symbol matcher is used to specify that a block of code throws a symbol. The most
basic form passes if any symbol is thrown:

  expect { throw :foo }.to throw_symbol

You'll often want to specify that a particular symbol is thrown:

  expect { throw :foo }.to throw_symbol(:foo)

If you care about the additional argument given to throw, you can specify that as well:

  expect { throw :foo, 7 }.to throw_symbol(:foo, 7)
Scenarios
  1. basic usage
  2. specify thrown symbol
  3. specify thrown symbol and argument
basic usage
Given
a file named "throw_symbol_matcher_spec.rb" with: 
RSpec.describe "throw" do
  specify { expect { throw :foo    }.to     throw_symbol }
  specify { expect { throw :bar, 7 }.to     throw_symbol }
  specify { expect { 5 + 5         }.not_to throw_symbol }

  # deliberate failures
  specify { expect { throw :foo    }.not_to throw_symbol }
  specify { expect { throw :bar, 7 }.not_to throw_symbol }
  specify { expect { 5 + 5         }.to     throw_symbol }
end
When
I run rspec throw_symbol_matcher_spec.rb
Then
the output should contain all of these:
6 examples, 3 failures
expected no Symbol to be thrown, got :foo
expected no Symbol to be thrown, got :bar
expected a Symbol to be thrown, got nothing
specify thrown symbol
Given
a file named "throw_symbol_matcher_spec.rb" with: 
RSpec.describe "throw symbol" do
  specify { expect { throw :foo    }.to     throw_symbol(:foo) }
  specify { expect { throw :foo, 7 }.to     throw_symbol(:foo) }
  specify { expect { 5 + 5         }.not_to throw_symbol(:foo) }
  specify { expect { throw :bar    }.not_to throw_symbol(:foo) }

  # deliberate failures
  specify { expect { throw :foo    }.not_to throw_symbol(:foo) }
  specify { expect { throw :foo, 7 }.not_to throw_symbol(:foo) }
  specify { expect { 5 + 5         }.to     throw_symbol(:foo) }
  specify { expect { throw :bar    }.to     throw_symbol(:foo) }
end
When
I run rspec throw_symbol_matcher_spec.rb
Then
the output should contain all of these:
8 examples, 4 failures
expected :foo not to be thrown, got :foo
expected :foo not to be thrown, got :foo with 7
expected :foo to be thrown, got nothing
expected :foo to be thrown, got :bar
specify thrown symbol and argument
Given
a file named "throw_symbol_argument_matcher_spec.rb" with: 
RSpec.describe "throw symbol with argument" do
  specify { expect { throw :foo, 7 }.to     throw_symbol(:foo, 7) }
  specify { expect { throw :foo, 8 }.not_to throw_symbol(:foo, 7) }
  specify { expect { throw :bar, 7 }.not_to throw_symbol(:foo, 7) }
  specify { expect { throw :foo    }.not_to throw_symbol(:foo, 7) }

  # deliberate failures
  specify { expect { throw :foo, 7 }.not_to throw_symbol(:foo, 7) }
  specify { expect { throw :foo, 8 }.to     throw_symbol(:foo, 7) }
  specify { expect { throw :bar, 7 }.to     throw_symbol(:foo, 7) }
  specify { expect { throw :foo    }.to     throw_symbol(:foo, 7) }
end
When
I run rspec throw_symbol_argument_matcher_spec.rb
Then
the output should contain all of these:
8 examples, 4 failures
expected :foo with 7 not to be thrown, got :foo with 7
expected :foo with 7 to be thrown, got :foo with 8
expected :foo with 7 to be thrown, got :bar
expected :foo with 7 to be thrown, got :foo with no argument

Last published 3 months ago by Jon Rowe.