Fix API sign in spec filename

spec/integration/api/sign_in_spec.rb

@@ -0,0 +1,30 @@
+describe 'API sign in' do
+  include AcceptanceHelpers
+
+  let(:user) { create :user }
+
+  def do_create
+    post api_sessions_path, format: :json, session: {
+      email:    user.email,
+      password: user.password
+    }
+  end
+
+  it 'signs the user in with valid credentials' do
+    do_create
+
+    expect(json).to eq(user: { id: user.id })
+  end
+
+  [:email, :password].each do |attr|
+    context "with invalid #{attr}" do
+      it 'rejects authentication' do
+        allow(user).to receive(attr).and_return(user.send(attr) + '_INVALID')
+        do_create
+
+        expect(response).to be_not_found
+        expect(response.body).to be_empty
+      end
+    end
+  end
+end