feat: make #remove_dependency available for gembytes scripts

Add the `Bundler::GemBytes::Actions.remove_dependency(gem_name)` method so it
is available to gembytes scripts.

lib/bundler/gem_bytes/actions.rb

@@ -30,6 +30,24 @@ def add_dependency(dependency_type, gem_name, version_constraint, force: false,
         ).call(source, path: gemspec)
         File.write(gemspec, updated_source)
       end
+
+      # Removes a dependency from the project's gemspec file
+      #
+      # @example
+      #   remove_dependency('rspec')
+      #
+      # @param gem_name [String] the name of the gem to add
+      # @param gemspec [String] the path to the gemspec file
+      #
+      # @return [void]
+      #
+      # @api public
+      #
+      def remove_dependency(gem_name, gemspec: Dir['*.gemspec'].first)
+        source = File.read(gemspec)
+        updated_source = Bundler::GemBytes::Gemspec::DeleteDependency.new(gem_name).call(source, path: gemspec)
+        File.write(gemspec, updated_source)
+      end
     end
   end
 end

lib/bundler/gem_bytes/gemspec.rb

@@ -7,4 +7,5 @@ module Gemspec; end
   end
 end
 
+require_relative 'gemspec/delete_dependency'
 require_relative 'gemspec/upsert_dependency'

lib/bundler/gem_bytes/gemspec/delete_dependency.rb

@@ -0,0 +1,216 @@
+# frozen_string_literal: true
+
+require 'parser/current'
+require 'rubocop-ast'
+require 'active_support/core_ext/object'
+
+module Bundler
+  module GemBytes
+    module Gemspec
+      # Delete a dependency in a gemspec file
+      #
+      # This class works by parsing the gemspec file into an AST and then walking the
+      # AST to find the Gem::Specification block (via #on_block). Once the block is
+      # found, AST within that block is walked to locate the dependency declarations
+      # (via #on_send). Any dependency declaration that matches the given gem name is
+      # collected into the found_dependencies array.
+      #
+      # Once the Gem::Specification block is fully processed, any dependencies on the
+      # given gem are deleted from the gemspec source.
+      #
+      # If the dependency is not found, the gemspec source is returned unmodified.
+      #
+      # @example
+      #   require 'bundler/gem_bytes'
+      #
+      #   delete_dependency = Bundler::GemBytes::Gemspec::DeleteDependency.new('test_tool')
+      #
+      #   gemspec_file = 'foo.gemspec'
+      #   gemspec = File.read(gemspec_file)
+      #   updated_gemspec = delete_dependency.call(gemspec, path: gemspec_file)
+      #   File.write(gemspec_file, updated_gemspec)
+      #
+      # @!attribute [r] gem_name
+      #   The name of the gem to add a dependency on (i.e. 'rubocop')
+      #   @return [String]
+      #   @api private
+      #
+      # @!attribute [r] receiver_name
+      #   The name of the receiver for the Gem::Specification block
+      #
+      #    i.e. 'spec' in `spec.add_dependency 'rubocop', '~> 1.0'`
+      #
+      #   @return [Symbol]
+      #   @api private
+      #
+      # @!attribute [r] found_gemspec_block
+      #   Whether the Gem::Specification block was found in the gemspec file
+      #
+      #   Only valid after calling `#call`.
+      #   @return [Boolean]
+      #   @api private
+      #
+      # @!attribute [r] found_dependencies
+      #   The dependencies found in the gemspec file
+      #
+      #   Only valid after calling `#call`.
+      #   @return [Array<Hash>]
+      #   @api private
+      #
+      # @api public
+      class DeleteDependency < Parser::TreeRewriter
+        # Create a new instance of a dependency upserter
+        # @example
+        #   command = Bundler::GemBytes::Gemspec::DeleteDependency.new('my_gem')
+        # @param gem_name [String] The name of the gem to add a dependency on
+        def initialize(gem_name)
+          super()
+
+          @gem_name = gem_name
+
+          @found_dependencies = []
+        end
+
+        # Returns the content of the gemspec file with the dependency deleted
+        #
+        # @param code [String] The content of the gemspec file
+        # @param path [String] This should be the path to the gemspspec file
+        #
+        #   path is used to generate error messages only
+        #
+        # @return [String] The updated gemspec content with the dependency deleted
+        #
+        # @raise [ArgumentError] if the Gem Specification block is not found in the given gemspec
+        #
+        # @example
+        #   code = File.read('project.gemspec')
+        #   command = Bundler::GemBytes::DeleteDependency.new('my_gem')
+        #   updated_code = command.call(code)
+        #   puts updated_code
+        #
+        def call(code, path: '(string)')
+          @found_gemspec_block = false
+          rewrite(*parse(code, path)).tap do |_result|
+            raise ArgumentError, 'Gem::Specification block not found' unless found_gemspec_block
+          end
+        end
+
+        attr_reader :gem_name, :receiver_name, :found_gemspec_block, :found_dependencies
+
+        # Handles block nodes within the AST to locate the Gem Specification block
+        #
+        # @param node [Parser::AST::Node] The block node within the AST
+        # @return [void]
+        # @api private
+        def on_block(node)
+          return if receiver_name # already processing the Gem Specification block
+
+          @found_gemspec_block = true
+          @receiver_name = gem_specification_pattern.match(node)
+
+          return unless receiver_name
+
+          super # process the children of this node to find the existing dependencies
+
+          delete_dependencies
+
+          @receiver_name = nil
+        end
+
+        # Handles `send` nodes within the AST to locate dependency calls
+        #
+        # If receiver_name is not present then we are not in a Gem Specification block.
+        #
+        # @param node [Parser::AST::Node] The `send` node to check for dependency patterns
+        # @return [void]
+        # @api private
+        def on_send(node)
+          return unless receiver_name.present?
+          return unless (match = dependency_pattern.match(node))
+
+          found_dependencies << { node:, match: }
+        end
+
+        private
+
+        # Parses the given code into an AST
+        # @param code [String] The code to parse
+        # @param path [String] The path to the file being parsed (used for error messages only)
+        # @return [Array<Parser::AST::Node, Parser::Source::Buffer>] The AST and buffer
+        # @api private
+        def parse(code, path)
+          buffer = Parser::Source::Buffer.new(path, source: code)
+          processed_source = RuboCop::AST::ProcessedSource.new(code, ruby_version, path)
+          unless processed_source.valid_syntax?
+            raise "Invalid syntax in #{path}\n#{processed_source.diagnostics.map(&:render).join("\n")}"
+          end
+
+          ast = processed_source.ast
+          [buffer, ast]
+        end
+
+        # Deletes any dependency on the given gem within the Gem::Specification block
+        # @param node [Parser::AST::Node] The block node within the AST
+        # @return [void]
+        # @api private
+        def delete_dependencies
+          found_dependencies.each do |found_dependency|
+            dependency_node = found_dependency[:node]
+            remove(range_including_leading_spaces(dependency_node))
+          end
+        end
+
+        # Returns the range of the dependency node including any leading spaces & newline
+        # @param node [Parser::AST::Node] The node
+        # @return [Parser::Source::Range] The range of the dependency node
+        # @api private
+        def range_including_leading_spaces(node)
+          leading_spaces = leading_whitespace_count(node)
+          range = node.loc.expression
+          range.with(begin_pos: range.begin_pos - leading_spaces - 1, end_pos: range.end_pos)
+        end
+
+        # Returns the # of leading whitespace chars in the source line before the node
+        # @param node [Parser::AST::Node] The node
+        # @return [Integer] The number of leading whitespace characters
+        # @api private
+        def leading_whitespace_count(node)
+          match_data = node.loc.expression.source_line.match(/^\s*/)
+          match_data ? match_data[0].size : 0
+        end
+
+        # Returns the Ruby version in use as a float (MAJOR.MINOR only)
+        # @return [Float] The Ruby version number, e.g., 3.0
+        # @api private
+        def ruby_version = RUBY_VERSION.match(/^(?<version>\d+\.\d+)/)['version'].to_f
+
+        # The pattern to match a dependency declaration in the AST
+        # @return [RuboCop::AST::NodePattern] The dependency pattern
+        # @api private
+        def dependency_pattern
+          # :nocov: JRuby give false positive for this line being uncovered by tests
+          @dependency_pattern ||=
+            RuboCop::AST::NodePattern.new(<<~PATTERN)
+              (send
+                { (send _ :#{receiver_name}) | (lvar :#{receiver_name}) }
+                ${ :add_dependency :add_runtime_dependency :add_development_dependency }
+                (str #{gem_name ? "$\"#{gem_name}\"" : '$_gem_name'})
+                <(str $_version_constraint) ...>
+              )
+            PATTERN
+          # :nocov:
+        end
+
+        # The pattern to match the Gem::Specification block in the AST
+        # @return [RuboCop::AST::NodePattern] The Gem::Specification pattern
+        # @api private
+        def gem_specification_pattern
+          @gem_specification_pattern ||=
+            RuboCop::AST::NodePattern.new(<<~PATTERN)
+              (block (send (const (const nil? :Gem) :Specification) :new)(args (arg $_)) ...)
+            PATTERN
+        end
+      end
+    end
+  end
+end

lib/bundler/gem_bytes/gemspec/upsert_dependency.rb

@@ -304,7 +304,7 @@ def dependency_type_method
           dependency_type == :development ? :add_development_dependency : :add_dependency
         end
 
-        # The patter to match a dependency declaration in the AST
+        # The pattern to match a dependency declaration in the AST
         # @return [RuboCop::AST::NodePattern] The dependency pattern
         # @api private
         def dependency_pattern

spec/features/add_dependency.feature

@@ -1,18 +1,20 @@
-Feature: Add or update a dependency to the project's gemspec
+Feature: Runs a gembytes script
 
-  Scenario: Add a dependency
+  Scenario: Add and remove a dependency
 
     Given a gem project named "foo" with the bundler-gem_bytes plugin installed
     And the project has a gemspec containing:
       """
       Gem::Specification.new do |spec|
         spec.name = 'foo'
         spec.version = '1.0'
+        spec.add_dependency 'bar', '>= 0.9'
       end
       """
     And a gem-bytes script "gem_bytes_script" containing:
       """
-      add_dependency :runtime, 'foo', '>= 1.0'
+      remove_dependency 'bar'
+      add_dependency :runtime, 'baz', '>= 1.0'
       """
     When I run "bundle gem-bytes gem_bytes_script"
     Then the command should have succeeded
@@ -21,7 +23,7 @@ Feature: Add or update a dependency to the project's gemspec
       Gem::Specification.new do |spec|
         spec.name = 'foo'
         spec.version = '1.0'
-        spec.add_dependency 'foo', '>= 1.0'
+        spec.add_dependency 'baz', '>= 1.0'
       end
       """
 

spec/lib/bundler/gem_bytes/actions_spec.rb

@@ -48,4 +48,36 @@
       end
     end
   end
+
+  describe '.remove_dependency' do
+    subject { instance.remove_dependency(gem_name) }
+
+    let(:gem_name) { 'rspec' }
+
+    it 'remove the dependency from the gemspec' do
+      # Make a temporary directory to work in
+      Dir.mktmpdir do |temp_dir|
+        Dir.chdir(temp_dir) do
+          # Create a new gemspec file
+          gemspec_file = 'my_gem.gemspec'
+          File.write(gemspec_file, <<~GEMSPEC)
+            Gem::Specification.new do |spec|
+              spec.name = 'my_gem'
+              spec.version = '0.1.0'
+              spec.add_development_dependency 'rspec', '~> 3.13'
+            end
+          GEMSPEC
+
+          # remove the dependency
+          instance.remove_dependency(gem_name)
+
+          # Read the gemspec file
+          gemspec_content = File.read(gemspec_file)
+
+          # Check that the dependency was removed
+          expect(gemspec_content).not_to include("spec.add_development_dependency 'rspec', '~> 3.13'")
+        end
+      end
+    end
+  end
 end