Don't overwrite existing lndhub wallet credentials

spec/jobs/create_lndhub_wallet_job_spec.rb

@@ -23,6 +23,24 @@ RSpec.describe CreateLndhubWalletJob, type: :job do
     expect(user.ln_password).to eq("def456")
   end
 
+  context "with existing credentials stored" do
+    before do
+      user.ln_login = "foo"
+      user.ln_password = "bar"
+      user.save!
+    end
+
+    it "does not create a new LndHub account" do
+      perform_enqueued_jobs { job }
+
+      expect(WebMock).to_not have_requested(:post, "http://10.1.1.163:3023/create")
+
+      user.reload
+      expect(user.ln_login).to eq("foo")
+      expect(user.ln_password).to eq("bar")
+    end
+  end
+
   after do
     clear_enqueued_jobs
     clear_performed_jobs