Add spec for Projects::GraphsController#languages

spec/controllers/projects/graphs_controller_spec.rb

+require 'spec_helper'
+require 'ostruct'
+
+describe Projects::GraphsController do
+  let(:project) { create(:project) }
+  let(:user)    { create(:user) }
+
+  before do
+    sign_in(user)
+    project.team << [user, :master]
+  end
+
+  describe 'GET #languages' do
+    let(:linguist_repository) do
+      OpenStruct.new(languages: {
+                       'Ruby'         => 1000,
+                       'CoffeeScript' => 350,
+                       'PowerShell'   => 15
+                     })
+    end
+
+    let(:expected_values) do
+      ps_color = "##{Digest::SHA256.hexdigest('PowerShell')[0...6]}"
+      [
+        # colors from Linguist:
+        { value: 73.26, label: "Ruby",         color: "#701516", highlight: "#701516" },
+        { value: 25.64, label: "CoffeeScript", color: "#244776", highlight: "#244776" },
+        # colors from SHA256 fallback:
+        { value: 1.1,   label: "PowerShell",   color: ps_color,  highlight: ps_color  }
+      ]
+    end
+
+    before do
+      allow(Linguist::Repository).to receive(:new).and_return(linguist_repository)
+    end
+
+    it 'sets the correct colour according to language' do
+      get(:languages, namespace_id: project.namespace.path, project_id: project.path, id: 'master')
+
+      expect(assigns(:languages)).to eq(expected_values)
+    end
+  end
+end