4 files changed, 21 insertions, 2 deletions
diff --git a/lib/constraints/user_url_constrainer.rb b/lib/constraints/user_url_constrainer.rb
index ef38d47d5c6..504a0f5d93e 100644
--- a/lib/constraints/user_url_constrainer.rb
+++ b/lib/constraints/user_url_constrainer.rb
@@ -2,6 +2,6 @@ require 'constraints/namespace_url_constrainer'
 
 class UserUrlConstrainer < NamespaceUrlConstrainer
   def find_resource(id)
-    User.find_by_username(id)
+    User.find_by('lower(username) = ?', id.downcase)
   end
 end
diff --git a/spec/lib/constraints/group_url_constrainer_spec.rb b/spec/lib/constraints/group_url_constrainer_spec.rb
new file mode 100644
index 00000000000..f0b75a664f2
--- /dev/null
+++ b/spec/lib/constraints/group_url_constrainer_spec.rb
@@ -0,0 +1,10 @@
+require 'spec_helper'
+
+describe GroupUrlConstrainer, lib: true do
+  let!(:username) { create(:group, path: 'gitlab-org') }
+
+  describe '#find_resource' do
+    it { expect(!!subject.find_resource('gitlab-org')).to be_truthy }
+    it { expect(!!subject.find_resource('gitlab-com')).to be_falsey }
+  end
+end
diff --git a/spec/lib/constraints/namespace_url_constrainer_spec.rb b/spec/lib/constraints/namespace_url_constrainer_spec.rb
index 8940fd6b94e..a5feaacb8ee 100644
--- a/spec/lib/constraints/namespace_url_constrainer_spec.rb
+++ b/spec/lib/constraints/namespace_url_constrainer_spec.rb
@@ -2,7 +2,6 @@ require 'spec_helper'
 
 describe NamespaceUrlConstrainer, lib: true do
   let!(:group) { create(:group, path: 'gitlab') }
-  subject { NamespaceUrlConstrainer.new }
 
   describe '#matches?' do
     context 'existing namespace' do
diff --git a/spec/lib/constraints/user_url_constrainer_spec.rb b/spec/lib/constraints/user_url_constrainer_spec.rb
new file mode 100644
index 00000000000..4b26692672f
--- /dev/null
+++ b/spec/lib/constraints/user_url_constrainer_spec.rb
@@ -0,0 +1,10 @@
+require 'spec_helper'
+
+describe UserUrlConstrainer, lib: true do
+  let!(:username) { create(:user, username: 'dz') }
+
+  describe '#find_resource' do
+    it { expect(!!subject.find_resource('dz')).to be_truthy }
+    it { expect(!!subject.find_resource('john')).to be_falsey }
+  end
+end