added tests for cat --ex N and edit --ex N, all passing except on RBX

test/helper.rb

@@ -27,6 +27,25 @@ class << Pry
   end
 end
 
+class MockPryException
+  attr_accessor :bt_index
+  attr_accessor :backtrace
+
+  def initialize(*backtrace)
+    @backtrace = backtrace
+    @bt_index = 0
+  end
+
+  def message
+    "mock exception"
+  end
+
+  def bt_source_location_for(index)
+    backtrace[index] =~ /(.*):(\d+)/
+    [$1, $2.to_i]
+  end
+end
+
 # are we on Jruby platform?
 def jruby?
   defined?(RUBY_ENGINE) && RUBY_ENGINE =~ /jruby/
@@ -136,6 +155,17 @@ class Pry
   end
 end
 
+# Open a temp file and yield it to the block, closing it after
+# @return [String] The path of the temp file
+def temp_file
+  file = Tempfile.new("tmp")
+  yield file
+  file.flush
+  file.path
+ensure
+  file.close
+end
+
 
 CommandTester = Pry::CommandSet.new do
   command "command1", "command 1 test" do

test/test_default_commands/test_introspection.rb

@@ -122,6 +122,55 @@ describe "Pry::DefaultCommands::Introspection" do
       end
     end
 
+    describe "with --ex NUM" do
+      before do
+        Pry.config.editor = proc do |file, line|
+          @__ex_file__ = file
+          @__ex_line__ = line
+          nil
+        end
+      end
+
+      it 'should start editor on first level of backtrace when --ex used with no argument ' do
+        pry_instance = Pry.new(:input => StringIO.new("edit -n --ex"), :output => StringIO.new)
+        pry_instance.last_exception = MockPryException.new("a:1", "b:2", "c:3")
+        pry_instance.rep(self)
+        @__ex_file__.should == "a"
+        @__ex_line__.should == 1
+      end
+
+      it 'should start editor on first level of backtrace when --ex 0 used ' do
+        pry_instance = Pry.new(:input => StringIO.new("edit -n --ex 0"), :output => StringIO.new)
+        pry_instance.last_exception = MockPryException.new("a:1", "b:2", "c:3")
+        pry_instance.rep(self)
+        @__ex_file__.should == "a"
+        @__ex_line__.should == 1
+      end
+
+      it 'should start editor on second level of backtrace when --ex 1 used' do
+        pry_instance = Pry.new(:input => StringIO.new("edit -n --ex 1"), :output => StringIO.new)
+        pry_instance.last_exception = MockPryException.new("a:1", "b:2", "c:3")
+        pry_instance.rep(self)
+        @__ex_file__.should == "b"
+        @__ex_line__.should == 2
+      end
+
+      it 'should start editor on third level of backtrace when --ex 2 used' do
+        pry_instance = Pry.new(:input => StringIO.new("edit -n --ex 2"), :output => StringIO.new)
+        pry_instance.last_exception = MockPryException.new("a:1", "b:2", "c:3")
+        pry_instance.rep(self)
+        @__ex_file__.should == "c"
+        @__ex_line__.should == 3
+      end
+
+      it 'should display error message when backtrace level is out of bounds (using --ex 4)' do
+        pry_instance = Pry.new(:input => StringIO.new("edit -n --ex 4"), :output => str_output = StringIO.new)
+        pry_instance.last_exception = MockPryException.new("a:1", "b:2", "c:3")
+        pry_instance.rep(self)
+        str_output.string.should =~ /Exception has no associated file/
+      end
+    end
+
     describe "without FILE" do
       it "should edit the current expression if it's incomplete" do
         mock_pry("def a", "edit")

test/test_default_commands/test_shell.rb

@@ -5,6 +5,7 @@ describe "Pry::DefaultCommands::Shell" do
 
     # this doesnt work so well on rbx due to differences in backtrace
     # so we currently skip rbx until we figure out a workaround
+    describe "with --ex" do
       if !rbx?
         it 'cat --ex should correctly display code that generated exception even if raised in repl' do
           mock_pry("this raises error", "cat --ex").should =~ /\d+:(\s*) this raises error/
@@ -15,4 +16,76 @@ describe "Pry::DefaultCommands::Shell" do
         end
       end
     end
+
+    describe "with --ex N" do
+      it 'should cat first level of backtrace when --ex used with no argument ' do
+        pry_instance = Pry.new(:input => StringIO.new("cat --ex"), :output => str_output = StringIO.new)
+        file_name = temp_file do |f|
+          f << "bt number 1"
+        end
+        pry_instance.last_exception = MockPryException.new("#{file_name}:1", "x", "x")
+        pry_instance.rep(self)
+        str_output.string.should =~ /bt number 1/
+      end
+
+      it 'should cat first level of backtrace when --ex 0 used ' do
+        pry_instance = Pry.new(:input => StringIO.new("cat --ex 0"), :output => str_output = StringIO.new)
+        file_name = temp_file do |f|
+          f << "bt number 1"
+        end
+        pry_instance.last_exception = MockPryException.new("#{file_name}:1", "x", "x")
+        pry_instance.rep(self)
+        str_output.string.should =~ /bt number 1/
+      end
+
+      it 'should cat second level of backtrace when --ex 1 used ' do
+        pry_instance = Pry.new(:input => StringIO.new("cat --ex 1"), :output => str_output = StringIO.new)
+        file_name = temp_file do |f|
+          f << "bt number 2"
+        end
+        pry_instance.last_exception = MockPryException.new("x", "#{file_name}:1", "x")
+        pry_instance.rep(self)
+        str_output.string.should =~ /bt number 2/
+      end
+
+      it 'should cat third level of backtrace when --ex 2 used ' do
+        pry_instance = Pry.new(:input => StringIO.new("cat --ex 2"), :output => str_output = StringIO.new)
+        file_name = temp_file do |f|
+          f << "bt number 3"
+        end
+        pry_instance.last_exception = MockPryException.new("x", "x", "#{file_name}:1")
+        pry_instance.rep(self)
+        str_output.string.should =~ /bt number 3/
+      end
+
+      it 'should show error when backtrace level out of bounds  ' do
+        pry_instance = Pry.new(:input => StringIO.new("cat --ex 3"), :output => str_output = StringIO.new)
+        pry_instance.last_exception = MockPryException.new("x", "x", "x")
+        pry_instance.rep(self)
+        str_output.string.should =~ /No Exception or Exception has no associated file/
+      end
+
+      it 'each successive cat --ex should show the next level of backtrace, and going past the final level should return to the first' do
+        file_names = []
+        file_names << temp_file { |f| f << "bt number 0" }
+        file_names << temp_file { |f| f << "bt number 1" }
+        file_names << temp_file { |f| f << "bt number 2" }
+
+        pry_instance = Pry.new(:input => StringIO.new("cat --ex\n" * (file_names.size + 1)),
+                               :output => str_output = StringIO.new)
+
+        pry_instance.last_exception = MockPryException.new(*file_names.map { |f| "#{f}:1" })
+
+        file_names.each_with_index do |f, idx|
+          pry_instance.rep(self)
+          str_output.string.should =~ /bt number #{idx}/
+        end
+
+        str_output.reopen
+        pry_instance.rep(self)
+        str_output.string.should =~ /bt number 0/
+      end
+
+    end
+  end
 end