Fix warnings spy so it doesn't capture more things than necessary

spec/warnings_spy/reader.rb

@@ -5,7 +5,6 @@ class WarningsSpy
     def initialize(filesystem)
       @warnings_file = filesystem.warnings_file
 
-      @recording = false
       @current_group = []
       @warning_groups = []
     end
@@ -27,37 +26,16 @@ class WarningsSpy
     private
 
     def process_line(line)
-      if backtrace_line?(line)
-        unless recording?
-          start_of_error = find_start_of_error
-
-          if start_of_error
-            _, start_of_error_index = start_of_error
-            @current_group = current_group[start_of_error_index..-1]
-          end
-
-          @recording = true
-        end
-      else
-        if recording?
-          add_group(current_group)
-          current_group.clear
-        end
-
-        @recording = false
+      if start_of_group?(line)
+        add_group(current_group)
+        current_group.clear
       end
 
       current_group << line
     end
 
-    def find_start_of_error
-      current_group.each_with_index.to_a.reverse.detect do |line, _|
-        start_of_error?(line)
-      end
-    end
-
-    def start_of_error?(line)
-      line =~ /^.+?:\d+:in `[^']+':/
+    def start_of_group?(line)
+      line =~ /^\W/
     end
 
     def add_group(group)
@@ -71,13 +49,5 @@ class WarningsSpy
         group == group_to_be_added
       end
     end
-
-    def backtrace_line?(line)
-      line =~ /^\s+/
-    end
-
-    def recording?
-      @recording
-    end
   end
 end