[ruby/irb] Add a warning for when the history path doesn't exist

(https://github.com/ruby/irb/pull/852)

* Add a warning for when the history path doesn't exist

* warn when the directory does not exist

* added test for when the history_file does not exist

* Update lib/irb/history.rb

---------

9e6fa67212

Co-authored-by: Stan Lo <stan001212@gmail.com>

lib/irb/history.rb

@@ -59,6 +59,12 @@ module IRB
           append_history = true
         end
 
+        pathname = Pathname.new(history_file)
+        unless Dir.exist?(pathname.dirname)
+          warn "Warning: The directory to save IRB's history file does not exist. Please double check `IRB.conf[:HISTORY_FILE]`'s value."
+          return
+        end
+
         File.open(history_file, (append_history ? 'a' : 'w'), 0o600, encoding: IRB.conf[:LC_MESSAGES]&.encoding) do |f|
           hist = history.map{ |l| l.scrub.split("\n").join("\\\n") }
           unless append_history

test/irb/test_history.rb

@@ -167,6 +167,19 @@ module TestIRB
       $VERBOSE = verbose_bak
     end
 
+    def test_history_does_not_raise_when_history_file_directory_does_not_exist
+      backup_history_file = IRB.conf[:HISTORY_FILE]
+      IRB.conf[:SAVE_HISTORY] = 1
+      IRB.conf[:HISTORY_FILE] = "fake/fake/fake/history_file"
+      io = TestInputMethodWithRelineHistory.new
+
+      assert_nothing_raised do
+        io.save_history
+      end
+    ensure
+      IRB.conf[:HISTORY_FILE] = backup_history_file
+    end
+
     private
 
     def history_concurrent_use_for_input_method(input_method)