src/derails/passive_resistance/testing/assertions.rb
# frozen_string_literal: true

require "passive_resistance/core_ext/enumerable"

module PassiveResistance
  module Testing
    module Assertions
      UNTRACKED = Object.new # :nodoc:

      # Asserts that an expression is not truthy. Passes if +object+ is +nil+ or
      # +false+. "Truthy" means "considered true in a conditional" like <tt>if
      # foo</tt>.
      #
      #   assert_not nil    # => true
      #   assert_not false  # => true
      #   assert_not 'foo'  # => Expected "foo" to be nil or false
      #
      # An error message can be specified.
      #
      #   assert_not foo, 'foo should be false'
      def assert_not(object, message = nil)
        message ||= -> { "Expected #{mu_pp(object)} to be nil or false" }
        assert !object, message
      end

      # Asserts that a block raises one of +exp+. This is an enhancement of the
      # standard Minitest assertion method with the ability to test error
      # messages.
      #
      #   assert_raises(ArgumentError, match: /incorrect param/i) do
      #     perform_service(param: 'exception')
      #   end
      #
      def assert_raises(*exp, match: nil, &block)
        error = super(*exp, &block)
        assert_match(match, error.message) if match
        error
      end
      alias :assert_raise :assert_raises

      # Assertion that the block should not raise an exception.
      #
      # Passes if evaluated code in the yielded block raises no exception.
      #
      #   assert_nothing_raised do
      #     perform_service(param: 'no_exception')
      #   end
      def assert_nothing_raised
        yield.tap { assert(true) }
      rescue => error
        raise Minitest::UnexpectedError.new(error)
      end

      # Test numeric difference between the return value of an expression as a
      # result of what is evaluated in the yielded block.
      #
      #   assert_difference 'Article.count' do
      #     post :create, params: { article: {...} }
      #   end
      #
      # An arbitrary expression is passed in and evaluated.
      #
      #   assert_difference 'Article.last.comments(:reload).size' do
      #     post :create, params: { comment: {...} }
      #   end
      #
      # An arbitrary positive or negative difference can be specified.
      # The default is +1+.
      #
      #   assert_difference 'Article.count', -1 do
      #     post :delete, params: { id: ... }
      #   end
      #
      # An array of expressions can be passed in and evaluated.
      #
      #   assert_difference [ 'Article.count', 'Post.count' ], 2 do
      #     post :create, params: { article: {...} }
      #   end
      #
      # A hash of expressions/numeric differences can be passed in and evaluated.
      #
      #   assert_difference({ 'Article.count' => 1, 'Notification.count' => 2 }) do
      #     post :create, params: { article: {...} }
      #   end
      #
      # A lambda, a list of lambdas or a hash of lambdas/numeric differences can be passed in and evaluated:
      #
      #   assert_difference ->{ Article.count }, 2 do
      #     post :create, params: { article: {...} }
      #   end
      #
      #   assert_difference [->{ Article.count }, ->{ Post.count }], 2 do
      #     post :create, params: { article: {...} }
      #   end
      #
      #   assert_difference ->{ Article.count } => 1, ->{ Notification.count } => 2 do
      #     post :create, params: { article: {...} }
      #   end
      #
      # An error message can be specified.
      #
      #   assert_difference 'Article.count', -1, 'An Article should be destroyed' do
      #     post :delete, params: { id: ... }
      #   end
      def assert_difference(expression, *args, &block)
        expressions =
          if expression.is_a?(Hash)
            message = args[0]
            expression
          else
            difference = args[0] || 1
            message = args[1]
            Array(expression).index_with(difference)
          end

        exps = expressions.keys.map { |e|
          e.respond_to?(:call) ? e : lambda { eval(e, block.binding) }
        }
        before = exps.map(&:call)

        retval = _assert_nothing_raised_or_warn("assert_difference", &block)

        expressions.zip(exps, before) do |(code, diff), exp, before_value|
          actual = exp.call
          rich_message = -> do
            code_string = code.respond_to?(:call) ? _callable_to_source_string(code) : code
            error = "`#{code_string}` didn't change by #{diff}, but by #{actual - before_value}"
            error = "#{message}.\n#{error}" if message
            error
          end
          assert_equal(before_value + diff, actual, rich_message)
        end

        retval
      end

      # Assertion that the numeric result of evaluating an expression is not
      # changed before and after invoking the passed in block.
      #
      #   assert_no_difference 'Article.count' do
      #     post :create, params: { article: invalid_attributes }
      #   end
      #
      # A lambda can be passed in and evaluated.
      #
      #   assert_no_difference -> { Article.count } do
      #     post :create, params: { article: invalid_attributes }
      #   end
      #
      # An error message can be specified.
      #
      #   assert_no_difference 'Article.count', 'An Article should not be created' do
      #     post :create, params: { article: invalid_attributes }
      #   end
      #
      # An array of expressions can also be passed in and evaluated.
      #
      #   assert_no_difference [ 'Article.count', -> { Post.count } ] do
      #     post :create, params: { article: invalid_attributes }
      #   end
      def assert_no_difference(expression, message = nil, &block)
        assert_difference expression, 0, message, &block
      end

      # Assertion that the result of evaluating an expression is changed before
      # and after invoking the passed in block.
      #
      #   assert_changes 'Status.all_good?' do
      #     post :create, params: { status: { ok: false } }
      #   end
      #
      # You can pass the block as a string to be evaluated in the context of
      # the block. A lambda can be passed for the block as well.
      #
      #   assert_changes -> { Status.all_good? } do
      #     post :create, params: { status: { ok: false } }
      #   end
      #
      # The assertion is useful to test side effects. The passed block can be
      # anything that can be converted to string with #to_s.
      #
      #   assert_changes :@object do
      #     @object = 42
      #   end
      #
      # The keyword arguments +:from+ and +:to+ can be given to specify the
      # expected initial value and the expected value after the block was
      # executed. The comparison is done using case equality (===), which means
      # you can specify patterns or classes:
      #
      #   # Exact value match
      #   assert_changes :@object, from: nil, to: :foo do
      #     @object = :foo
      #   end
      #
      #   # Case equality
      #   assert_changes -> { user.token }, to: /\w{32}/ do
      #     user.generate_token
      #   end
      #
      #   # Type check
      #   assert_changes -> { current_error }, from: nil, to: RuntimeError do
      #     raise "Oops"
      #   end
      #
      # An error message can be specified.
      #
      #   assert_changes -> { Status.all_good? }, 'Expected the status to be bad' do
      #     post :create, params: { status: { incident: true } }
      #   end
      def assert_changes(expression, message = nil, from: UNTRACKED, to: UNTRACKED, &block)
        exp = expression.respond_to?(:call) ? expression : -> { eval(expression.to_s, block.binding) }

        before = exp.call
        retval = _assert_nothing_raised_or_warn("assert_changes", &block)

        unless from == UNTRACKED
          rich_message = -> do
            error = "Expected change from #{from.inspect}, got #{before.inspect}"
            error = "#{message}.\n#{error}" if message
            error
          end
          assert from === before, rich_message
        end

        after = exp.call

        rich_message = -> do
          code_string = expression.respond_to?(:call) ? _callable_to_source_string(expression) : expression
          error = "`#{code_string}` didn't change"
          error = "#{error}. It was already #{to.inspect}" if before == to
          error = "#{message}.\n#{error}" if message
          error
        end
        refute_equal before, after, rich_message

        unless to == UNTRACKED
          rich_message = -> do
            error = "Expected change to #{to.inspect}, got #{after.inspect}\n"
            error = "#{message}.\n#{error}" if message
            error
          end
          assert to === after, rich_message
        end

        retval
      end

      # Assertion that the result of evaluating an expression is not changed before
      # and after invoking the passed in block.
      #
      #   assert_no_changes 'Status.all_good?' do
      #     post :create, params: { status: { ok: true } }
      #   end
      #
      # Provide the optional keyword argument +:from+ to specify the expected
      # initial value. The comparison is done using case equality (===), which means
      # you can specify patterns or classes:
      #
      #   # Exact value match
      #   assert_no_changes -> { Status.all_good? }, from: true do
      #     post :create, params: { status: { ok: true } }
      #   end
      #
      #   # Case equality
      #   assert_no_changes -> { user.token }, from: /\w{32}/ do
      #     user.touch
      #   end
      #
      #   # Type check
      #   assert_no_changes -> { current_error }, from: RuntimeError do
      #     retry_operation
      #   end
      #
      # An error message can be specified.
      #
      #   assert_no_changes -> { Status.all_good? }, 'Expected the status to be good' do
      #     post :create, params: { status: { ok: false } }
      #   end
      def assert_no_changes(expression, message = nil, from: UNTRACKED, &block)
        exp = expression.respond_to?(:call) ? expression : -> { eval(expression.to_s, block.binding) }

        before = exp.call
        retval = _assert_nothing_raised_or_warn("assert_no_changes", &block)

        unless from == UNTRACKED
          rich_message = -> do
            error = "Expected initial value of #{from.inspect}, got #{before.inspect}"
            error = "#{message}.\n#{error}" if message
            error
          end
          assert from === before, rich_message
        end

        after = exp.call

        rich_message = -> do
          code_string = expression.respond_to?(:call) ? _callable_to_source_string(expression) : expression
          error = "`#{code_string}` changed"
          error = "#{message}.\n#{error}" if message
          error
        end

        if before.nil?
          assert_nil after, rich_message
        else
          assert_equal before, after, rich_message
        end

        retval
      end

      private
        def _assert_nothing_raised_or_warn(assertion, &block)
          assert_nothing_raised(&block)
        rescue Minitest::UnexpectedError => e
          if tagged_logger && tagged_logger.warn?
            warning = <<~MSG
              #{self.class} - #{name}: #{e.error.class} raised.
              If you expected this exception, use `assert_raises` as near to the code that raises as possible.
              Other block based assertions (e.g. `#{assertion}`) can be used, as long as `assert_raises` is inside their block.
            MSG
            tagged_logger.warn warning
          end

          raise
        end

        def _callable_to_source_string(callable)
          if defined?(RubyVM::InstructionSequence) && callable.is_a?(Proc)
            iseq = RubyVM::InstructionSequence.of(callable)
            source =
              if iseq.script_lines
                iseq.script_lines.join("\n")
              elsif File.readable?(iseq.absolute_path)
                File.read(iseq.absolute_path)
              end

            return callable unless source

            location = iseq.to_a[4][:code_location]
            return callable unless location

            lines = source.lines[(location[0] - 1)..(location[2] - 1)]
            lines[-1] = lines[-1].byteslice(...location[3])
            lines[0] = lines[0].byteslice(location[1]...)
            source = lines.join.strip

            # We ignore procs defined with do/end as they are likely multi-line anyway.
            if source.start_with?("{")
              source.delete_suffix!("}")
              source.delete_prefix!("{")
              source.strip!
              # It won't read nice if the callable contains multiple
              # lines, and it should be a rare occurrence anyway.
              # Same if it takes arguments.
              if !source.include?("\n") && !source.start_with?("|")
                return source
              end
            end
          end

          callable
        end
    end
  end
end
