diff --git a/spec/controllers/settings/sharing_controller_spec.rb b/spec/controllers/settings/sharing_controller_spec.rb
new file mode 100644
index 00000000..6755845a
--- /dev/null
+++ b/spec/controllers/settings/sharing_controller_spec.rb
@@ -0,0 +1,133 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+describe Settings::SharingController, type: :controller do
+  describe "#edit" do
+    subject { get :edit }
+
+    it "redirects to the sign in page when not signed in" do
+      expect(subject).to redirect_to new_user_session_path
+    end
+
+    context "user signed in" do
+      let(:user) { FactoryBot.create(:user) }
+
+      before { sign_in user }
+
+      it "renders the edit template" do
+        expect(subject).to render_template(:edit)
+      end
+    end
+  end
+
+  describe "#update" do
+    subject { patch :update, params: { user: user_params } }
+    let(:user_params) do
+      {
+        sharing_enabled:    "1",
+        sharing_autoclose:  "1",
+        sharing_custom_url: "",
+      }
+    end
+
+    it "redirects to the sign in page when not signed in" do
+      expect(subject).to redirect_to new_user_session_path
+    end
+
+    context "user signed in" do
+      let(:user) { FactoryBot.create :user }
+
+      before { sign_in user }
+
+      it "renders the edit template" do
+        expect(subject).to render_template(:edit)
+      end
+
+      it "updates the user's sharing preferences" do
+        expect { subject }
+          .to change { user.reload.slice(:sharing_enabled, :sharing_autoclose, :sharing_custom_url).values }
+          .from([false, false, nil])
+          .to([true, true, ""])
+      end
+
+      it "sets the success flash" do
+        subject
+        expect(flash[:success]).to eq(I18n.t("settings.sharing.update.success"))
+      end
+
+      context "when passed a valid url" do
+        let(:user_params) do
+          super().merge(
+            sharing_custom_url: "https://example.com/share?text="
+          )
+        end
+
+        it "renders the edit template" do
+          expect(subject).to render_template(:edit)
+        end
+
+        it "updates the user's sharing preferences" do
+          expect { subject }
+            .to change { user.reload.slice(:sharing_enabled, :sharing_autoclose, :sharing_custom_url).values }
+            .from([false, false, nil])
+            .to([true, true, "https://example.com/share?text="])
+        end
+
+        it "sets the success flash" do
+          subject
+          expect(flash[:success]).to eq(I18n.t("settings.sharing.update.success"))
+        end
+      end
+
+      context "when passed an invalid url" do
+        let(:user_params) do
+          super().merge(
+            sharing_custom_url: "nfs://example.com/data"
+          )
+        end
+
+        it "renders the edit template" do
+          expect(subject).to render_template(:edit)
+        end
+
+        it "updates the user's sharing preferences" do
+          expect { subject }
+            .not_to(change { user.reload.slice(:sharing_enabled, :sharing_autoclose, :sharing_custom_url).values })
+        end
+
+        it "sets the error flash" do
+          subject
+          expect(flash[:error]).to eq(I18n.t("settings.sharing.update.error"))
+        end
+      end
+
+      context "when unticking boolean settings" do
+        let(:user_params) do
+          super().merge(
+            sharing_enabled:   "0",
+            sharing_autoclose: "0"
+          )
+        end
+
+        let(:user) { FactoryBot.create :user, sharing_enabled: true, sharing_autoclose: true, sharing_custom_url: "https://example.com/share?text=" }
+
+        it "renders the edit template" do
+          expect(subject).to render_template(:edit)
+        end
+
+        it "updates the user's sharing preferences" do
+          expect { subject }
+            .to change { user.reload.slice(:sharing_enabled, :sharing_autoclose, :sharing_custom_url).values }
+            .from([true, true, "https://example.com/share?text="])
+            .to([false, false, ""])
+        end
+
+        it "sets the success flash" do
+          subject
+          expect(flash[:success]).to eq(I18n.t("settings.sharing.update.success"))
+        end
+      end
+    end
+  end
+end