control_d_handler: don't mutate eval_string within the handler

This is a preparational step for #1824
(Enabling `# frozen_string_literal: true` in `~/.pryc` crashes most operations)

Alternative to https://github.com/pry/pry/pull/2030
(config: delete the `control_d_handler` option)

We had to jump a few hoops to change how the handler works. The problem is that
mutation is the default expected behaviour. Therefore, we had to change its
API. There's no need to pass `eval_string` because `pry_instance` already has it
as an attribute.

`config.control_d_handler` is a proxy proc, to preserve backwards compatibility
with users of old signature (one known user is Pry Byebug). The handler will
emit a warning if the old signature is used.

1 files changed, 21 insertions, 12 deletions

diff --git a/spec/control_d_handler_spec.rb b/spec/control_d_handler_spec.rb
index 5e21ccbe..030cefd6 100644
--- a/spec/control_d_handler_spec.rb
+++ b/spec/control_d_handler_spec.rb
@@ -1,48 +1,57 @@
 RSpec.describe Pry::ControlDHandler do
   context "when given eval string is non-empty" do
-    let(:eval_string) { 'hello' }
-    let(:pry_instance) { Pry.new }
+    let(:pry_instance) do
+      Pry.new.tap do |p|
+        p.eval_string = 'hello'
+      end
+    end
 
     it "clears input buffer" do
-      described_class.default(eval_string, pry_instance)
-      expect(eval_string).to be_empty
+      described_class.default(pry_instance)
+      expect(pry_instance.eval_string).to be_empty
     end
   end
 
   context "when given eval string is empty & pry instance has one binding" do
-    let(:eval_string) { '' }
-    let(:pry_instance) { Pry.new.tap { |p| p.binding_stack = [binding] } }
+    let(:pry_instance) do
+      Pry.new.tap do |p|
+        p.eval_string = ''
+        p.binding_stack = [binding]
+      end
+    end
 
     it "throws :breakout" do
-      expect { described_class.default(eval_string, pry_instance) }
+      expect { described_class.default(pry_instance) }
         .to throw_symbol(:breakout)
     end
 
     it "clears binding stack" do
-      expect { described_class.default(eval_string, pry_instance) }
+      expect { described_class.default(pry_instance) }
         .to throw_symbol
       expect(pry_instance.binding_stack).to be_empty
     end
   end
 
   context "when given eval string is empty & pry instance has 2+ bindings" do
-    let(:eval_string) { '' }
     let(:binding1) { binding }
     let(:binding2) { binding }
     let(:binding_stack) { [binding1, binding2] }
 
     let(:pry_instance) do
-      Pry.new.tap { |p| p.binding_stack = binding_stack }
+      Pry.new.tap do |p|
+        p.eval_string = ''
+        p.binding_stack = binding_stack
+      end
     end
 
     it "saves a dup of the current binding stack in the 'cd' command" do
-      described_class.default(eval_string, pry_instance)
+      described_class.default(pry_instance)
       cd_state = pry_instance.commands['cd'].state
       expect(cd_state.old_stack).to eq([binding1, binding2])
     end
 
     it "pops the binding off the stack" do
-      described_class.default(eval_string, pry_instance)
+      described_class.default(pry_instance)
       expect(pry_instance.binding_stack).to eq([binding1])
     end
   end