= Gemspec

== Gemspec/DuplicatedAssignment

|===
| Enabled by default | Safe | Supports autocorrection | VersionAdded | VersionChanged

| Enabled
| Yes
| No
| 0.52
| -
|===

An attribute assignment method calls should be listed only once
in a gemspec.

Assigning to an attribute with the same name using `spec.foo =` will be
an unintended usage. On the other hand, duplication of methods such
as `spec.requirements`, `spec.add_runtime_dependency`, and others are
permitted because it is the intended use of appending values.

=== Examples

[source,ruby]
----
# bad
Gem::Specification.new do |spec|
  spec.name = 'rubocop'
  spec.name = 'rubocop2'
end

# good
Gem::Specification.new do |spec|
  spec.name = 'rubocop'
end

# good
Gem::Specification.new do |spec|
  spec.requirements << 'libmagick, v6.0'
  spec.requirements << 'A good graphics card'
end

# good
Gem::Specification.new do |spec|
  spec.add_runtime_dependency('parallel', '~> 1.10')
  spec.add_runtime_dependency('parser', '>= 2.3.3.1', '< 3.0')
end
----

=== Configurable attributes

|===
| Name | Default value | Configurable values

| Include
| `+**/*.gemspec+`
| Array
|===

== Gemspec/OrderedDependencies

|===
| Enabled by default | Safe | Supports autocorrection | VersionAdded | VersionChanged

| Enabled
| Yes
| Yes
| 0.51
| -
|===

Dependencies in the gemspec should be alphabetically sorted.

=== Examples

[source,ruby]
----
# bad
spec.add_dependency 'rubocop'
spec.add_dependency 'rspec'

# good
spec.add_dependency 'rspec'
spec.add_dependency 'rubocop'

# good
spec.add_dependency 'rubocop'

spec.add_dependency 'rspec'

# bad
spec.add_development_dependency 'rubocop'
spec.add_development_dependency 'rspec'

# good
spec.add_development_dependency 'rspec'
spec.add_development_dependency 'rubocop'

# good
spec.add_development_dependency 'rubocop'

spec.add_development_dependency 'rspec'

# bad
spec.add_runtime_dependency 'rubocop'
spec.add_runtime_dependency 'rspec'

# good
spec.add_runtime_dependency 'rspec'
spec.add_runtime_dependency 'rubocop'

# good
spec.add_runtime_dependency 'rubocop'

spec.add_runtime_dependency 'rspec'

# good only if TreatCommentsAsGroupSeparators is true
# For code quality
spec.add_dependency 'rubocop'
# For tests
spec.add_dependency 'rspec'
----

=== Configurable attributes

|===
| Name | Default value | Configurable values

| TreatCommentsAsGroupSeparators
| `true`
| Boolean

| ConsiderPunctuation
| `false`
| Boolean

| Include
| `+**/*.gemspec+`
| Array
|===

== Gemspec/RequiredRubyVersion

|===
| Enabled by default | Safe | Supports autocorrection | VersionAdded | VersionChanged

| Enabled
| Yes
| No
| 0.52
| 0.89
|===

Checks that `required_ruby_version` of gemspec is specified and
equal to `TargetRubyVersion` of .rubocop.yml.
Thereby, RuboCop to perform static analysis working on the version
required by gemspec.

=== Examples

[source,ruby]
----
# When `TargetRubyVersion` of .rubocop.yml is `2.5`.

# bad
Gem::Specification.new do |spec|
  # no `required_ruby_version` specified
end

# bad
Gem::Specification.new do |spec|
  spec.required_ruby_version = '>= 2.4.0'
end

# bad
Gem::Specification.new do |spec|
  spec.required_ruby_version = '>= 2.6.0'
end

# good
Gem::Specification.new do |spec|
  spec.required_ruby_version = '>= 2.5.0'
end

# good
Gem::Specification.new do |spec|
  spec.required_ruby_version = '>= 2.5'
end

# good
Gem::Specification.new do |spec|
  spec.required_ruby_version = ['>= 2.5.0', '< 2.7.0']
end

# good
Gem::Specification.new do |spec|
  spec.required_ruby_version = '~> 2.5'
end
----

=== Configurable attributes

|===
| Name | Default value | Configurable values

| Include
| `+**/*.gemspec+`
| Array
|===

== Gemspec/RubyVersionGlobalsUsage

|===
| Enabled by default | Safe | Supports autocorrection | VersionAdded | VersionChanged

| Enabled
| Yes
| No
| 0.72
| -
|===

Checks that `RUBY_VERSION` constant is not used in gemspec.
Using `RUBY_VERSION` is dangerous because value of the
constant is determined by `rake release`.
It's possible to have dependency based on ruby version used
to execute `rake release` and not user's ruby version.

=== Examples

[source,ruby]
----
# bad
Gem::Specification.new do |spec|
  if RUBY_VERSION >= '2.5'
    spec.add_runtime_dependency 'gem_a'
  else
    spec.add_runtime_dependency 'gem_b'
  end
end

# good
Gem::Specification.new do |spec|
  spec.add_runtime_dependency 'gem_a'
end
----

=== Configurable attributes

|===
| Name | Default value | Configurable values

| Include
| `+**/*.gemspec+`
| Array
|===

=== References

* https://rubystyle.guide#no-ruby-version-in-the-gemspec
