rib: add some convenience for reused RIBs

app/models/rib.rb

@@ -36,4 +36,12 @@ def active?
   def inactive?
     !active?
   end
+
+  def reused?
+    siblings.any?
+  end
+
+  def siblings
+    Rib.where(iban: iban).excluding(self)
+  end
 end

spec/models/rib_spec.rb

@@ -47,4 +47,20 @@
       end
     end
   end
+
+  describe "reused?" do
+    context "without other ribs" do
+      it "is false" do
+        expect(rib).not_to be_reused
+      end
+    end
+
+    context "with multiple RIBS with the same IBAN" do
+      before { create(:rib, iban: rib.iban) }
+
+      it "returns true" do
+        expect(rib).to be_reused
+      end
+    end
+  end
 end