[ruby/irb] Add ri an alias to the show_doc command

(ruby/irb#1054)

ruby/irb@52e77dd113

Author: st0012

lib/irb/default_commands.rb

@@ -218,7 +218,8 @@ def load_command(command)
     )
 
     _register_with_aliases(:irb_show_doc, Command::ShowDoc,
-      [:show_doc, NO_OVERRIDE]
+      [:show_doc, NO_OVERRIDE],
+      [:ri, NO_OVERRIDE]
     )
 
     _register_with_aliases(:irb_info, Command::IrbInfo)

test/irb/test_command.rb

@@ -4,6 +4,15 @@
 require_relative "helper"
 
 module TestIRB
+  # In case when RDoc becomes a bundled gem, we may not be able to load it when running tests
+  # in ruby/ruby
+  HAS_RDOC = begin
+    require "rdoc"
+    true
+  rescue LoadError
+    false
+  end
+
   class CommandTestCase < TestCase
     def setup
       @pwd = Dir.pwd
@@ -767,18 +776,33 @@ def test_ls_with_no_singleton_class
   end
 
   class ShowDocTest < CommandTestCase
-    def test_show_doc
-      out, err = execute_lines("show_doc String#gsub")
-
-      # the former is what we'd get without document content installed, like on CI
-      # the latter is what we may get locally
-      possible_rdoc_output = [/Nothing known about String#gsub/, /gsub\(pattern\)/]
-      assert_not_include err, "[Deprecation]"
-      assert(possible_rdoc_output.any? { |output| output.match?(out) }, "Expect the `show_doc` command to match one of the possible outputs. Got:\n#{out}")
-    ensure
-      # this is the only way to reset the redefined method without coupling the test with its implementation
-      EnvUtil.suppress_warning { load "irb/command/help.rb" }
-    end if defined?(RDoc)
+    if HAS_RDOC
+      def test_show_doc
+        out, err = execute_lines("show_doc String#gsub")
+
+        # the former is what we'd get without document content installed, like on CI
+        # the latter is what we may get locally
+        possible_rdoc_output = [/Nothing known about String#gsub/, /gsub\(pattern\)/]
+        assert_not_include err, "[Deprecation]"
+        assert(possible_rdoc_output.any? { |output| output.match?(out) }, "Expect the `show_doc` command to match one of the possible outputs. Got:\n#{out}")
+      ensure
+        # this is the only way to reset the redefined method without coupling the test with its implementation
+        EnvUtil.suppress_warning { load "irb/command/help.rb" }
+      end
+
+      def test_ri
+        out, err = execute_lines("ri String#gsub")
+
+        # the former is what we'd get without document content installed, like on CI
+        # the latter is what we may get locally
+        possible_rdoc_output = [/Nothing known about String#gsub/, /gsub\(pattern\)/]
+        assert_not_include err, "[Deprecation]"
+        assert(possible_rdoc_output.any? { |output| output.match?(out) }, "Expect the `ri` command to match one of the possible outputs. Got:\n#{out}")
+      ensure
+        # this is the only way to reset the redefined method without coupling the test with its implementation
+        EnvUtil.suppress_warning { load "irb/command/help.rb" }
+      end
+    end
 
     def test_show_doc_without_rdoc
       _, err = without_rdoc do