Merge pull request #395 from RobinDaugherty/fix/393-pry-uninitialized…

…-constant

Fix Pry `uninitialized constant` exception

lib/better_errors/error_page.rb

@@ -45,9 +45,9 @@ def do_eval(opts)
         return { error: "REPL unavailable in this stack frame" }
       end
 
-      @repls[index] ||= get_repl(index, binding)
+      @repls[index] ||= REPL.provider.new(binding, exception)
 
-      send_input(index, code)
+      eval_and_respond(index, code)
     end
 
     def backtrace_frames
@@ -111,19 +111,7 @@ def inspect_value(obj)
       "<span class='unsupported'>(exception was raised in inspect)</span>"
     end
 
-    def get_repl(index, binding)
-      REPL.provider.new(binding).tap do |repl|
-        if repl.is_a?(REPL::Pry)
-          pry = repl.instance_variable_get(:@pry)
-          pry.instance_variable_set(
-            :@last_exception,
-            ::Pry::LastException.new(@exception.exception)
-          )
-        end
-      end
-    end
-
-    def send_input(index, code)
+    def eval_and_respond(index, code)
       result, prompt, prefilled_input = @repls[index].send_input(code)
 
       {

lib/better_errors/repl.rb

@@ -21,7 +21,9 @@ def self.detect
     end
 
     def self.test_provider(provider)
-      require provider[:impl]
+      # We must load this file instead of `require`ing it, since during our tests we want the file
+      # to be reloaded. In practice, this will only be called once, so `require` is not necessary.
+      load "#{provider[:impl]}.rb"
       true
     rescue LoadError
       false

lib/better_errors/repl/basic.rb

@@ -1,7 +1,7 @@
 module BetterErrors
   module REPL
     class Basic
-      def initialize(binding)
+      def initialize(binding, _exception)
         @binding = binding
       end
 

lib/better_errors/repl/pry.rb

@@ -36,17 +36,23 @@ def print(*args)
         end
       end
 
-      def initialize(binding)
+      def initialize(binding, exception)
         @fiber = Fiber.new do
           @pry.repl binding
         end
         @input = BetterErrors::REPL::Pry::Input.new
         @output = BetterErrors::REPL::Pry::Output.new
         @pry = ::Pry.new input: @input, output: @output
         @pry.hooks.clear_all if defined?(@pry.hooks.clear_all)
+        store_last_exception exception
         @fiber.resume
       end
 
+      def store_last_exception(exception)
+        return unless defined? ::Pry::LastException
+        @pry.instance_variable_set(:@last_exception, ::Pry::LastException.new(exception.exception))
+      end
+
       def send_input(str)
         local ::Pry.config, color: false, pager: false do
           @fiber.resume "#{str}\n"

spec/better_errors/error_page_spec.rb

@@ -88,5 +88,62 @@ def initialize(message = nil)
         expect(error_page.exception_message).not_to match(/\A\n\n/)
       end
     end
+
+    describe '#do_eval' do
+      let(:exception) { empty_binding.eval("raise") rescue $! }
+      subject(:do_eval) { error_page.do_eval("index" => 0, "source" => command) }
+      let(:command) { 'EvalTester.stuff_was_done(:yep)' }
+      before do
+        stub_const('EvalTester', eval_tester)
+      end
+      let(:eval_tester) { double('EvalTester', stuff_was_done: 'response') }
+
+      context 'with Pry disabled' do
+        it "evaluates the code" do
+          do_eval
+          expect(eval_tester).to have_received(:stuff_was_done).with(:yep)
+        end
+
+        it 'returns a hash of the code and its result' do
+          expect(do_eval).to include(
+            highlighted_input: /stuff_was_done/,
+            prefilled_input: '',
+            prompt: '>>',
+            result: "=> \"response\"\n",
+          )
+        end
+      end
+
+      context 'with Pry enabled' do
+        before do
+          BetterErrors.use_pry!
+          # Cause the provider to be unselected, so that it will be re-detected.
+          BetterErrors::REPL.provider = nil
+        end
+        after do
+          BetterErrors::REPL::PROVIDERS.shift
+          BetterErrors::REPL.provider = nil
+
+          # Ensure the Pry REPL file has not been included. If this is not done,
+          # the constant leaks into other examples.
+          BetterErrors::REPL.send(:remove_const, :Pry)
+        end
+
+        it "evaluates the code" do
+          BetterErrors::REPL.provider
+          do_eval
+          expect(eval_tester).to have_received(:stuff_was_done).with(:yep)
+        end
+
+        it 'returns a hash of the code and its result' do
+          expect(do_eval).to include(
+            highlighted_input: /stuff_was_done/,
+            prefilled_input: '',
+            prompt: '>>',
+            result: "=> \"response\"\n",
+          )
+        end
+      end
+    end
   end
 end

spec/better_errors/repl/basic_spec.rb

@@ -10,7 +10,9 @@ module REPL
         binding
       }
 
-      let(:repl) { Basic.new fresh_binding }
+      let!(:exception) { raise ZeroDivisionError, "you divided by zero you silly goose!" rescue $! }
+
+      let(:repl) { Basic.new(fresh_binding, exception) }
 
       it_behaves_like "a REPL provider"
     end

spec/better_errors/repl/pry_spec.rb

@@ -1,17 +1,29 @@
 require "spec_helper"
 require "pry"
-require "better_errors/repl/pry"
 require "better_errors/repl/shared_examples"
 
 module BetterErrors
   module REPL
     describe Pry do
+      before(:all) do
+        load "better_errors/repl/pry.rb"
+      end
+      after(:all) do
+        # Ensure the Pry REPL file has not been included. If this is not done,
+        # the constant leaks into other examples.
+        # In practice, this constant is only defined if `use_pry!` is called and then the
+        # REPL is used, causing BetterErrors::REPL to require the file.
+        BetterErrors::REPL.send(:remove_const, :Pry)
+      end
+
       let(:fresh_binding) {
         local_a = 123
         binding
       }
 
-      let(:repl) { Pry.new fresh_binding }
+      let!(:exception) { raise ZeroDivisionError, "you divided by zero you silly goose!" rescue $! }
+
+      let(:repl) { Pry.new(fresh_binding, exception) }
 
       it "does line continuation" do
         output, prompt, filled = repl.send_input ""