Module: DRYSpec::Helpers

Defined in:
lib/dryspec/helpers.rb

Instance Method Summary collapse

Instance Method Details

#for_subject(variable, &block) ⇒ Object

A shortcut for a combination of ‘context` and `subject`

Examples:

Multiple subjects from let variables


let(:foo) { 55 }
let(:bar) { 66 }

# Before
context 'subject: foo' do
  subject { foo }

  it { should eq(55) }
end

context 'subject: bar' do
  subject { bar }

  it { should eq(66) }
end

# After
for_subject(:foo) { it { should eq(55) } }
for_subject(:bar) { it { should eq(66) } }


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# File 'lib/dryspec/helpers.rb', line 127

def for_subject(variable, &block)
  context "subject: #{variable}" do
    subject { send(variable) }

    instance_eval(&block)
  end
end

#let_context(*args, &block) ⇒ Object

This allows us to simplify the case where we want to have a context which contains one or more ‘let` statements

Supports giving either a Hash or a String and a Hash as arguments In both cases the Hash will be used to define ‘let` statements When a String is specified that becomes the context description If String isn’t specified, Hash#inspect becomes the context description

Examples:

Defining a simple let variable

# Before
subject { a + 1 }
context('a is 1') do
  let(:a) { 1 }
  it { should eq 2 }
end

# After
subject { a + 1 }
let_context(a: 1) { it { should eq 2 } }

Giving a descriptive string

subject { a + 1 }
let_context('Negative number', a: -1) { it { should eq 0 } }

Multiple variables

subject { a + b }
let_context(a: 1, b: 2) { it { should eq 3 } }


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# File 'lib/dryspec/helpers.rb', line 30

def let_context(*args, &block)
  context_string, hash =
    case args.map(&:class)
    when [String, Hash] then ["#{args[0]} #{args[1]}", args[1]]
    when [Hash] then [args[0].inspect, args[0]]
    end

  context(context_string) do
    hash.each { |var, value| let(var) { value } }

    instance_eval(&block)
  end
end

#subject_should_not_raise(*args) ⇒ Object

Allows you to simply specify that the subject should not raise an exception. Takes no arguments or arguments of an exception class, a string, or both.

As with RSpec’s basic ‘not_to raise_error` matcher, if you give a specific error, other unexpected errors may be swallowed silently

Examples:

Subject does not raise an error

# Before
subject { 1 }
it 'should not raise an exception' do
  expect { subject }.not_to raise_error
end

# After
subject { 1 }
subject_should_not_raise


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# File 'lib/dryspec/helpers.rb', line 94

def subject_should_not_raise(*args)
  error, message = args
  it_string = "subject should not raise #{error}"
  it_string += " (#{message.inspect})" if message

  it it_string do
    expect { subject }.not_to raise_error error, message
  end
end

#subject_should_raise(*args) ⇒ Object

Allows you to simply specify that the subject should raise an exception Takes no arguments or arguments of an exception class, a string, or both.

As with RSpec’s basic ‘to raise_error` matcher, if you don’t give an error then the an unexpected error may cause your test to pass incorrectly

Examples:

Raising a string

# Before
subject { fail 'Test' }
it "should raise 'Test'" do
  expect { subject }.to raise_error 'Test'
end

# After
subject { fail 'Test' }
subject_should_raise 'Test'

Raising an exception class

subject { fail ArgumentError }
subject_should_raise ArgumentError

Raising an exception class and string

subject { fail ArgumentError, 'Test' }
subject_should_raise ArgumentError, 'Test'


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# File 'lib/dryspec/helpers.rb', line 68

def subject_should_raise(*args)
  error, message = args
  it_string = "subject should raise #{error}"
  it_string += " (#{message.inspect})" if message

  it it_string do
    expect { subject }.to raise_error error, message
  end
end