[plugin_generator] move development dependencies from *.gemspec.erb…

… to `Gemfile.erb` (fastlane#21726)

* Make Gemfile a template and move dev dependencies to it, in plugin generator.

* Remove now-unnecessary rule exception on RuboCop.

* Update comments.

fastlane.gemspec

@@ -15,10 +15,6 @@ config['require'] = [
 config.delete('inherit_from')
 config.delete('CrossPlatform/ForkUsage')
 config.delete('Lint/IsStringUsage')
-# We declare development dependencies in the Gemspec file because we use dynamic values in its template
-config['Gemspec/DevelopmentDependencies'] = {
-  'Enabled' => false
-}
 
 File.write("#{lib}/fastlane/plugins/template/.rubocop.yml", YAML.dump(config))
 

fastlane/lib/fastlane/plugins/template/%gem_name%.gemspec.erb

@@ -21,15 +21,4 @@ Gem::Specification.new do |spec|
   # since this would cause a circular dependency
 
   # spec.add_dependency 'your-dependency', '~> 1.0.0'
-
-  spec.add_development_dependency('bundler')
-  spec.add_development_dependency('fastlane', '>= <%= Fastlane::VERSION %>')
-  spec.add_development_dependency('pry')
-  spec.add_development_dependency('rake')
-  spec.add_development_dependency('rspec')
-  spec.add_development_dependency('rspec_junit_formatter')
-  spec.add_development_dependency('rubocop', '<%= Fastlane::RUBOCOP_REQUIREMENT %>')
-  spec.add_development_dependency('rubocop-performance')
-  spec.add_development_dependency('rubocop-require_tools')
-  spec.add_development_dependency('simplecov')
 end

fastlane/lib/fastlane/plugins/template/Gemfile.erb

@@ -0,0 +1,27 @@
+source('https://rubygems.org')
+
+# Provides a consistent environment for Ruby projects by tracking and installing exact gem versions.
+gem 'bundler'
+# Automation tool for mobile developers.
+gem 'fastlane', '>= <%= Fastlane::VERSION %>'
+# Provides an interactive debugging environment for Ruby.
+gem 'pry'
+# A simple task automation tool.
+gem 'rake'
+# Behavior-driven testing tool for Ruby.
+gem 'rspec'
+# Formatter for RSpec to generate JUnit compatible reports.
+gem 'rspec_junit_formatter'
+# A Ruby static code analyzer and formatter.
+gem 'rubocop', '<%= Fastlane::RUBOCOP_REQUIREMENT %>'
+# A collection of RuboCop cops for performance optimizations.
+gem 'rubocop-performance'
+# A RuboCop extension focused on enforcing tools.
+gem 'rubocop-require_tools'
+# SimpleCov is a code coverage analysis tool for Ruby.
+gem 'simplecov'
+
+gemspec
+
+plugins_path = File.join(File.dirname(__FILE__), 'fastlane', 'Pluginfile')
+eval_gemfile(plugins_path) if File.exist?(plugins_path)

fastlane/spec/plugins_specs/plugin_generator_spec.rb

@@ -103,10 +103,21 @@
       gemfile_lines = File.read(gemfile).lines
 
       [
-        "source('https://rubygems.org')\n",
-        "gemspec\n"
+        "source('https://rubygems.org')",
+        "gem 'bundler'",
+        "gem 'fastlane', '>= #{Fastlane::VERSION}'",
+        "gem 'pry'",
+        "gem 'rake'",
+        "gem 'rspec'",
+        "gem 'rspec_junit_formatter'",
+        "gem 'rubocop', '#{Fastlane::RUBOCOP_REQUIREMENT}'",
+        "gem 'rubocop-performance'",
+        "gem 'rubocop-require_tools'",
+        "gem 'simplecov'",
+        "gemspec"
       ].each do |line|
-        expect(gemfile_lines).to include(line)
+        # Expect them to match approximately, e.g. using regex
+        expect(gemfile_lines).to include("#{line}\n")
       end
     end
 
@@ -224,18 +235,7 @@
         expect(gemspec.version).to eq(Gem::Version.new('0.1.0'))
         expect(gemspec.email).to eq(email)
         expect(gemspec.summary).to eq(summary)
-        expect(gemspec.development_dependencies).to contain_exactly(
-          Gem::Dependency.new("pry", Gem::Requirement.new([">= 0"]), :development),
-          Gem::Dependency.new("bundler", Gem::Requirement.new([">= 0"]), :development),
-          Gem::Dependency.new("rspec", Gem::Requirement.new([">= 0"]), :development),
-          Gem::Dependency.new("rspec_junit_formatter", Gem::Requirement.new([">= 0"]), :development),
-          Gem::Dependency.new("rake", Gem::Requirement.new([">= 0"]), :development),
-          Gem::Dependency.new("rubocop", Gem::Requirement.new([Fastlane::RUBOCOP_REQUIREMENT]), :development),
-          Gem::Dependency.new("rubocop-require_tools", Gem::Requirement.new([">= 0"]), :development),
-          Gem::Dependency.new("rubocop-performance", Gem::Requirement.new([">= 0"]), :development),
-          Gem::Dependency.new("simplecov", Gem::Requirement.new([">= 0"]), :development),
-          Gem::Dependency.new("fastlane", Gem::Requirement.new([">= #{Fastlane::VERSION}"]), :development)
-        )
+        expect(gemspec.development_dependencies).to eq([])
       end
     end