extract transition_through

spec/spec_helper.rb

@@ -1,15 +1,13 @@
 # frozen_string_literal: true
 
+require 'transition_through'
 require 'verbose_migrations'
 require 'active_support'
 require 'active_record'
 require 'rails'
 require 'sqlite3'
 require 'logger'
 
-require 'rspec/mocks/standalone'
-require 'prism'
-
 ActiveRecord::Base.logger = ActiveSupport::TaggedLogging.new(
   ActiveSupport::Logger.new(STDOUT),
 )
@@ -21,95 +19,6 @@
 
 RSpec::Matchers.define_negated_matcher :not_change, :change
 
-module TransitionThrough
-  ##
-  # TransitionExpression walks a Prism AST until we find a transition expression, e.g.:
-  #
-  #   expect { ... }.to transition { ... }.through [...]
-  #
-  # Returns the transition state in the transition block.
-  class TransitionExpression < Prism::Visitor
-    Result = Data.define(:receiver, :method_name)
-
-    attr_reader :at, :result
-
-    def initialize(at:) = @at = at
-
-    def visit_call_node(node)
-      case node
-      in name: :transition, block: Prism::BlockNode(body: Prism::Node(body: [Prism::CallNode(receiver:, name: method_name)]), location:) if location.start_line == at
-        @result = Result.new(receiver:, method_name:)
-      else
-        super
-      end
-    end
-  end
-
-  class Matcher
-    include RSpec::Matchers, RSpec::Matchers::Composable, RSpec::Mocks::ExampleMethods
-
-    attr_reader :state_block
-
-    def initialize(state_block)
-      @state_block     = state_block
-      @expected_states = []
-      @actual_states   = []
-    end
-
-    def supports_block_expectations? = true
-    def matches?(expect_block)
-      path, start_line = state_block.source_location
-
-      # walk the ast until we find our transition expression
-      exp = TransitionExpression.new(at: start_line)
-      ast = Prism.parse_file(path)
-
-      ast.value.accept(exp)
-
-      # get the actual transitioning object from the state block's binding
-      receiver = state_block.binding.eval(exp.result.receiver.name.to_s)
-
-      # get the receivers method names for stubbing
-      setter = receiver.method(:"#{exp.result.method_name}=")
-      getter = receiver.method(exp.result.method_name)
-
-      # record initial state
-      @actual_states = [getter.call]
-
-      # stub the setter so that we can track state transitions
-      allow(receiver).to receive(setter.name) do |value|
-        @actual_states << value
-
-        setter.call(value)
-      end
-
-      # call the expect block
-      expect_block.call
-
-      # assert states match
-      @actual_states == @expected_states
-    end
-
-    def through(*values)
-      @expected_states = values.flatten(1)
-
-      self
-    end
-
-    def failure_message
-      "expected block to transition through #{@expected_states.inspect} but it transitioned through #{@actual_states.inspect}"
-    end
-
-    def failure_message_when_negated
-      "expected block not to transition through #{@expected_states.inspect} but it did"
-    end
-  end
-
-  module Methods
-    def transition(&block) = Matcher.new(block)
-  end
-end
-
 RSpec.configure do |config|
   config.include TransitionThrough::Methods
 

verbose_migrations.gemspec

@@ -19,6 +19,7 @@ Gem::Specification.new do |spec|
   spec.add_dependency 'rails', '>= 6.0'
 
   spec.add_development_dependency 'rspec-rails'
+  spec.add_development_dependency 'transition_through', '1.0.0.pre.beta.1'
   spec.add_development_dependency 'sqlite3', '~> 1.4'
   spec.add_development_dependency 'prism'
 end