Add rubocop linter for Truncate (#2200)

.changeset/light-rockets-do.md

@@ -0,0 +1,7 @@
+---
+'@primer/view-components': minor
+---
+
+Add rubocop linter for `Truncate` component
+
+<!-- Changed components: _none_ -->

.erb-lint.yml

@@ -27,3 +27,5 @@ linters:
         Enabled: false
         Exclude:
           - app/components/primer/layout_component.html.erb
+      Primer/Migrations/TruncateComponent:
+        Enabled: true

lib/primer/view_components/linters.rb

@@ -1,3 +1,4 @@
 # frozen_string_literal: true
 
 Dir[File.join(__dir__, "linters", "*.rb")].sort.each { |file| require file }
+Dir[File.join(__dir__, "linters", "migrations", "*.rb")].sort.each { |file| require file }

lib/primer/view_components/linters/migrations/truncate_component.rb

@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Migrations
+      # Lint & autocorrect Truncate components
+      class TruncateComponent < RuboCop::Cop::Cop
+        INVALID_MESSAGE = <<~STR
+          `Primer::Truncate` is deprecated. Please use `Primer::Beta::Truncate` instead!
+        STR
+
+        def_node_matcher :truncate_component, <<~PATTERN
+          (send (const (const nil? :Primer) :Truncate) :new ...)
+        PATTERN
+
+        def_node_matcher :hash_with_inline_value?, <<~PATTERN
+          (hash ... (pair (sym :inline) (...)) ... )
+        PATTERN
+
+        def_node_matcher :truncate_with_tag?, <<~PATTERN
+          (hash ... (pair (sym :tag) (...)) ... )
+        PATTERN
+
+        def on_send(node)
+          return unless truncate_component(node)
+
+          add_offense(node, message: INVALID_MESSAGE)
+        end
+
+        def autocorrect(node)
+          return if hash_with_inline_value?(node.arguments.first)
+
+          lambda do |corrector|
+            if node.arguments.first.nil? == false
+              corrector.replace(node.children.first, "Primer::Beta::Truncate")
+              corrector.insert_after(node.arguments.first, ", tag: :div") unless truncate_with_tag?(node.arguments.first)
+            else
+              corrector.replace(node.loc.expression, "Primer::Beta::Truncate.new(tag: :div)")
+            end
+          end
+        end
+      end
+    end
+  end
+end

test/lib/rubocop/truncate_component_test.rb

@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+require "lib/cop_test_case"
+
+class ButtonMigrationTest < CopTestCase
+  def cop_class
+    ::RuboCop::Cop::Migrations::TruncateComponent
+  end
+
+  def test_no_warnings_on_beta_truncate
+    investigate(cop, <<~RUBY)
+      Primer::Beta::Truncate.new()
+    RUBY
+
+    assert_empty cop.offenses
+  end
+
+  def test_warn_on_truncate_no_args
+    investigate(cop, <<~RUBY)
+      Primer::Truncate.new()
+    RUBY
+
+    assert_equal 1, cop.offenses.count
+    assert_equal "Primer::Beta::Truncate.new(tag: :div)", cop.offenses.first.corrector.rewrite.strip
+  end
+
+  def test_warn_on_truncate_simple_arg
+    investigate(cop, <<~RUBY)
+      Primer::Truncate.new(0)
+    RUBY
+
+    assert_equal 1, cop.offenses.count
+    assert cop.offenses.first.corrector.present?
+
+    assert_equal "Primer::Beta::Truncate.new(0, tag: :div)", cop.offenses.first.corrector.rewrite.strip
+  end
+
+  def test_warn_no_fix_truncate_inline
+    investigate(cop, <<~RUBY)
+      Primer::Truncate.new(inline: true)
+    RUBY
+
+    assert_equal 1, cop.offenses.count
+    refute cop.offenses.first.corrector.present?
+  end
+
+  def test_do_not_add_tag_if_tag_is_present
+    investigate(cop, <<~RUBY)
+      Primer::Truncate.new(tag: :span)
+    RUBY
+
+    assert_equal 1, cop.offenses.count
+    assert cop.offenses.first.corrector.present?
+
+    assert_equal "Primer::Beta::Truncate.new(tag: :span)", cop.offenses.first.corrector.rewrite.strip
+  end
+end