Do not strip leading and trailing whitespace from raw posts.

app/models/post.rb

@@ -31,7 +31,7 @@ class Post < ActiveRecord::Base
   has_many :post_actions
 
   validates_presence_of :raw, :user_id, :topic_id
-  validates :raw, length: {in: SiteSetting.min_post_length..SiteSetting.max_post_length}
+  validates :raw, stripped_length: {in: SiteSetting.min_post_length..SiteSetting.max_post_length}
   validate :raw_quality
   validate :max_mention_validator
   validate :max_images_validator
@@ -59,10 +59,6 @@ class Post < ActiveRecord::Base
     TopicUser.auto_track(self.user_id, self.topic_id, TopicUser::NotificationReasons::CREATED_POST)
   end
 
-  before_validation do
-    self.raw.strip! if self.raw.present?
-  end
-
   def raw_quality
 
     sentinel = TextSentinel.new(self.raw, min_entropy: SiteSetting.body_min_entropy)
@@ -214,7 +210,7 @@ class Post < ActiveRecord::Base
     # We only filter quotes when there is exactly 1
     return cooked unless (quote_count == 1)
 
-    parent_raw = parent_post.raw.sub(/\[quote.+\/quote\]/m, '').strip
+    parent_raw = parent_post.raw.sub(/\[quote.+\/quote\]/m, '')
 
     if raw[parent_raw] or (parent_raw.size < SHORT_POST_CHARS)
       return cooked.sub(/\<aside.+\<\/aside\>/m, '')

app/models/stripped_length_validator.rb

@@ -0,0 +1,14 @@
+class StrippedLengthValidator < ActiveModel::EachValidator
+  def validate_each(record, attribute, value)
+    unless value.nil?
+      stripped_length = value.strip.length
+      range = options[:in]
+      record.errors.add attribute, (options[:message] || "is too short (minimum is #{range.begin}).") unless
+          stripped_length >= range.begin
+      record.errors.add attribute, (options[:message] || "is too long (maximum is #{range.end}).") unless
+          stripped_length <= range.end
+    else
+      record.errors.add attribute, (options[:message] || "is required.")
+    end
+  end
+end

lib/text_sentinel.rb

@@ -20,8 +20,8 @@ class TextSentinel
     @opts = opts || {}
 
     if @text.present?
-      @text.strip! 
       @text.gsub!(/ +/m, ' ') if @opts[:remove_interior_spaces]
+      @text.strip! if @opts[:strip]
     end
   end
 
@@ -29,19 +29,20 @@ class TextSentinel
     TextSentinel.new(text, 
                      min_entropy: SiteSetting.title_min_entropy,
                      max_word_length: SiteSetting.max_word_length,
-                     remove_interior_spaces: true)    
+                     remove_interior_spaces: true,
+                     strip: true)
   end
 
   # Entropy is a number of how many unique characters the string needs. 
   def entropy
     return 0 if @text.blank?
-    @entropy ||= @text.each_char.to_a.uniq.size
+    @entropy ||= @text.strip.each_char.to_a.uniq.size
   end
 
   def valid?    
 
     # Blank strings are not valid
-    return false if @text.blank?
+    return false if @text.blank? || @text.strip.blank?
 
     # Entropy check if required
     return false if @opts[:min_entropy].present? and (entropy < @opts[:min_entropy])

spec/components/text_sentinel_spec.rb

@@ -38,10 +38,6 @@ describe TextSentinel do
 
   context "cleaning up" do
 
-    it "strips leading or trailing whitespace" do
-      TextSentinel.new("   \t  test \t  ").text.should == "test"
-    end
-
     it "allows utf-8 chars" do
       TextSentinel.new("йȝîûηыეமிᚉ⠛").text.should == "йȝîûηыეமிᚉ⠛"
     end
@@ -49,15 +45,37 @@ describe TextSentinel do
     context "interior spaces" do
 
       let(:spacey_string) { "hello     there's weird     spaces here." }
+      let(:unspacey_string) { "hello there's weird spaces here." }
 
       it "ignores intra spaces by default" do
         TextSentinel.new(spacey_string).text.should == spacey_string
       end
 
       it "fixes intra spaces when enabled" do
-        TextSentinel.new(spacey_string, remove_interior_spaces: true).text.should == "hello there's weird spaces here."
+        TextSentinel.new(spacey_string, remove_interior_spaces: true).text.should == unspacey_string
       end
 
+      it "fixes intra spaces in titles" do
+        TextSentinel.title_sentinel(spacey_string).text.should == unspacey_string
+      end
+
+    end
+
+    context "stripping whitespace" do
+      let(:spacey_string) { "   \t  test \t  " }
+      let(:unspacey_string) { "test" }
+
+      it "does not strip leading and trailing whitespace by default" do
+        TextSentinel.new(spacey_string).text.should == spacey_string
+      end
+
+      it "strips leading and trailing whitespace when enabled" do
+        TextSentinel.new(spacey_string, strip: true).text.should == unspacey_string
+      end
+
+      it "strips leading and trailing whitespace in titles" do
+        TextSentinel.title_sentinel(spacey_string).text.should == unspacey_string
+      end
     end
 
   end