Revert "Merge pull request #39304 from zenspider/zenspider/backtrace_filter_should_never_return_empty"

This reverts commit 2eb7aa111b, reversing
changes made to 0b28f0c39c.

Rails backtrace cleaner needs to be able to return empty traces to
separate application code from the framework code and not report
exceptions that happen inside only framework code.

See
345de17caf/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb (L72).

actionpack/test/dispatch/debug_exceptions_test.rb

@@ -540,9 +540,7 @@ class DebugExceptionsTest < ActionDispatch::IntegrationTest
 
     output = StringIO.new
     backtrace_cleaner = ActiveSupport::BacktraceCleaner.new
-    def backtrace_cleaner.clean(bt, _)
+    backtrace_cleaner.add_silencer { true }
-      []
-    end
 
     env = { "action_dispatch.show_exceptions"   => true,
             "action_dispatch.logger"            => Logger.new(output),

activesupport/lib/active_support/backtrace_cleaner.rb

@@ -104,29 +104,28 @@ module ActiveSupport
         add_silencer { |line| line.start_with?(RbConfig::CONFIG["rubylibdir"]) }
       end
 
-      # Process +ary+ via +filters+ using +method+, ensuring
-      # _something_ gets returned.
-      def process_collection(ary, filters, method)
-        filters.reduce(ary) { |bt, f| bt.public_send(method) { |line| f.call(line) } }
-      end
-
-      # Use @filters to transform the backtrace via map
       def filter_backtrace(backtrace)
-        process_collection backtrace, @filters, :map
+        @filters.each do |f|
+          backtrace = backtrace.map { |line| f.call(line) }
+        end
+
+        backtrace
       end
 
-      # Use @silencers to reject parts of the backtrace. Guarantee
-      # something non-empty is returned.
       def silence(backtrace)
-        result = process_collection backtrace, @silencers, :reject
+        @silencers.each do |s|
-        result.first ? result : backtrace.dup
+          backtrace = backtrace.reject { |line| s.call(line) }
+        end
+
+        backtrace
       end
 
-      # Use @silencers to select parts of the backtrace. Guarantee
-      # something non-empty is returned.
       def noise(backtrace)
-        result = backtrace.select { |line| @silencers.any? { |s| s.call(line) } }
+        backtrace.select do |line|
-        result.first ? result : backtrace.dup
+          @silencers.any? do |s|
+            s.call(line)
+          end
+        end
       end
   end
 end

activesupport/test/clean_backtrace_test.rb

@@ -42,17 +42,6 @@ class BacktraceCleanerSilencerTest < ActiveSupport::TestCase
   end
 end
 
-class BacktraceCleanerShouldNeverReturnEmpty < ActiveSupport::TestCase
-  test "backtrace should return a backtrace no matter what" do
-    @bc = ActiveSupport::BacktraceCleaner.new
-    @bc.add_silencer { |line| true }
-
-    bt = %w[ first second third ]
-
-    assert_equal bt, @bc.clean(bt.dup)
-  end
-end
-
 class BacktraceCleanerMultipleSilencersTest < ActiveSupport::TestCase
   def setup
     @bc = ActiveSupport::BacktraceCleaner.new
@@ -114,15 +103,15 @@ class BacktraceCleanerDefaultFilterAndSilencerTest < ActiveSupport::TestCase
   end
 
   test "should silence gems from the backtrace" do
-    backtrace = [ "#{Gem.path[0]}/gems/nosuchgem-1.2.3/lib/foo.rb", "other/file.rb" ]
+    backtrace = [ "#{Gem.path[0]}/gems/nosuchgem-1.2.3/lib/foo.rb" ]
     result = @bc.clean(backtrace)
-    assert_equal %w[other/file.rb], result
+    assert_empty result
   end
 
   test "should silence stdlib" do
-    backtrace = ["#{RbConfig::CONFIG["rubylibdir"]}/lib/foo.rb", "other/file.rb"]
+    backtrace = ["#{RbConfig::CONFIG["rubylibdir"]}/lib/foo.rb"]
     result = @bc.clean(backtrace)
-    assert_equal %w[other/file.rb], result
+    assert_empty result
   end
 
   test "should preserve lines that have a subpath matching a gem path" do