Add a few specs to user model

I noticed a few assertions of the has_many type were missing.
Also added a couple of specs which were testing in one direction only.
Just tipping my toes in discourse hope this helps a little.

spec/models/user_spec.rb

@@ -14,6 +14,9 @@ describe User do
   it { should have_many :views }
   it { should have_many :user_visits }
   it { should belong_to :approved_by }
+  it { should have_many :email_logs }
+  it { should have_many :topic_allowed_users }
+  it { should have_many :invites }
 
   it { should validate_presence_of :username }
   it { should validate_presence_of :email }
@@ -165,7 +168,30 @@ describe User do
         user.reload
         user.username_lower.should == new_username.downcase
       end
+    end
 
+    context 'failure' do
+      let(:wrong_username) { "" }
+      let(:username_before_change) { user.username }
+      let(:username_lower_before_change) { user.username_lower }
+
+      before do
+        @result = user.change_username(wrong_username)
+      end
+
+      it 'returns false' do
+        @result.should be_false
+      end
+
+      it 'should not change the username' do
+        user.reload
+        user.username.should == username_before_change
+      end
+
+      it 'should not change the username_lower' do
+        user.reload
+        user.username_lower.should == username_lower_before_change
+      end
     end
 
   end
@@ -191,6 +217,20 @@ describe User do
         end
       end
     end
+
+    it 'does not allow non moderators to delete all posts' do
+      invalid_guardian = Guardian.new(Fabricate(:user))
+
+      expect do
+        @user.delete_all_posts!(invalid_guardian)
+      end.to raise_error Discourse::InvalidAccess
+
+      @posts.each do |p|
+        p.reload
+        p.should be_present
+        p.topic.should be_present
+      end
+    end
   end
 
   describe 'new' do