Preserve whitespace alignment in wrap_lines

Split on /(\s+)/ instead of /\s+/ so multi-space gaps in help text
(e.g. option alignment) are preserved when wrapping lines.

Author: st0012

lib/irb/command/base.rb

@@ -63,20 +63,17 @@ def wrap_lines(text, width)
             next [line] if line.length <= width
 
             indent = line[/\A\s*/]
-            words = line.strip.split(/\s+/)
+            parts = line.strip.split(/(\s+)/)
             result = []
             current = indent.dup
-            words.each do |word|
-              if current == indent
-                current << word
-              elsif current.length + 1 + word.length <= width
-                current << ' ' << word
-              else
-                result << current
-                current = indent.dup + word
+            parts.each do |part|
+              if current != indent && current.length + part.length > width
+                result << current.rstrip
+                current = indent.dup
               end
+              current << part unless current == indent && part.match?(/\A\s+\z/)
             end
-            result << current unless current == indent
+            result << current.rstrip unless current == indent
             result
           end
         end

test/irb/test_input_method.rb

@@ -244,5 +244,19 @@ def test_doc_dialog_content_wraps_long_lines
         assert_operator stripped.length, :<=, 30, "Line exceeds width: #{line.inspect}"
       end
     end
+
+    def test_wrap_lines_preserves_whitespace_alignment
+      text = <<~TEXT
+        -g [query]  Filter the output with a query.
+        -a [aa]     Foo bar
+      TEXT
+      lines = IRB::Command::Base.send(:wrap_lines, text, 30)
+      expected = <<~EXPECTED.chomp
+        -g [query]  Filter the output
+        with a query.
+        -a [aa]     Foo bar
+      EXPECTED
+      assert_equal expected, lines.join("\n")
+    end
   end
 end