Fix tester for nested-instance case

spec/helpers/repl_tester.rb

@@ -1,6 +1,7 @@
 # This is for super-high-level integration testing.
 
 require 'thread'
+require 'delegate'
 
 class ReplTester
   class Input
@@ -9,24 +10,28 @@ class ReplTester
     end
 
     def readline(prompt)
-      awaken_tester
+      @tester_mailbox.push prompt
       mailbox.pop
     end
 
     def mailbox
       Thread.current[:mailbox]
     end
+  end
 
-    def awaken_tester
-      @tester_mailbox.push nil
+  class Output < SimpleDelegator
+    def clear
+      __setobj__(StringIO.new)
     end
   end
 
   def self.start(options = {}, &block)
     Thread.current[:mailbox] = Queue.new
     instance = nil
+    input    = Input.new(Thread.current[:mailbox])
+    output   = Output.new(StringIO.new)
 
-    redirect_pry_io Input.new(Thread.current[:mailbox]), StringIO.new do
+    redirect_pry_io input, output do
       instance = new(options)
       instance.instance_eval(&block)
       instance.ensure_exit
@@ -37,7 +42,7 @@ class ReplTester
     end
   end
 
-  attr_accessor :thread, :mailbox
+  attr_accessor :thread, :mailbox, :last_prompt
 
   def initialize(options = {})
     @pry     = Pry.new(options)
@@ -61,12 +66,12 @@ class ReplTester
   def input(input)
     reset_output
     repl_mailbox.push input
-    mailbox.pop # wait until the instance either calls readline or ends
+    self.last_prompt = mailbox.pop
   end
 
   # Assert that the current prompt matches the given string or regex.
   def prompt(match)
-    match.should === @pry.select_prompt
+    match.should === last_prompt
   end
 
   # Assert that the most recent output (since the last time input was called)
@@ -93,7 +98,7 @@ class ReplTester
   private
 
   def reset_output
-    @pry.output = Pry.output = StringIO.new
+    Pry.output.clear
   end
 
   def repl_mailbox

spec/pry_repl_spec.rb

@@ -14,7 +14,7 @@ describe "The REPL" do
   end
 
   describe "eval_string and binding_stack" do
-    it "shouldn't break if we start a nested session" do
+    it "shouldn't break if we start a nested REPL" do
       ReplTester.start do
         input  'Pry::REPL.new(_pry_, :target => 10).start'
         output ''
@@ -31,6 +31,23 @@ describe "The REPL" do
       end
     end
 
+    it "shouldn't break if we start a nested instance" do
+      ReplTester.start do
+        input  'Pry.start(10)'
+        output ''
+        prompt /10.*> $/
+
+        input  'self'
+        output '=> 10'
+
+        input  nil # Ctrl-D
+        output '=> nil' # return value of Pry session
+
+        input  'self'
+        output '=> main'
+      end
+    end
+
     it "shouldn't break if we pop bindings in Ruby" do
       ReplTester.start do
         input  'cd 10'
@@ -59,7 +76,7 @@ describe "The REPL" do
       ReplTester.start(:commands => set) do
         input  'def x'
         output ''
-        prompt /\* $/
+        prompt /\*   $/
 
         input  'hello!'
         output '=> "hello"'