Validate presence of essential params for diff rendering

This will avoid application errors generated by the assumption of the
presence of these params.

1 files changed, 40 insertions, 0 deletions

diff --git a/spec/controllers/projects/blob_controller_spec.rb b/spec/controllers/projects/blob_controller_spec.rb
new file mode 100644
index 00000000000..9444a50b1ce
--- /dev/null
+++ b/spec/controllers/projects/blob_controller_spec.rb
@@ -0,0 +1,40 @@
+require 'rails_helper'
+
+describe Projects::BlobController do
+  let(:project) { create(:project) }
+  let(:user)    { create(:user) }
+
+  before do
+    user = create(:user)
+    project.team << [user, :master]
+
+    sign_in(user)
+  end
+
+  describe 'GET diff' do
+    render_views
+
+    def do_get(opts = {})
+      params = { namespace_id: project.namespace.to_param,
+                 project_id: project.to_param,
+                 id: 'master/CHANGELOG' }
+      get :diff, params.merge(opts)
+    end
+
+    context 'when essential params are missing' do
+      it 'renders nothing' do
+        do_get
+
+        expect(response.body).to be_blank
+      end
+    end
+
+    context 'when essential params are present' do
+      it 'renders the diff content' do
+        do_get(since: 1, to: 5, offset: 10)
+
+        expect(response.body).to be_present
+      end
+    end
+  end
+end