Add kredits API with wallet balance endpoint

spec/requests/api/kredits_spec.rb

@@ -0,0 +1,43 @@
+require 'rails_helper'
+require 'webmock/rspec'
+
+RSpec.describe "/api/kredits", type: :request do
+
+  describe "GET /onchain_btc_balance" do
+    before do
+      stub_request(:get, "http://btcpay.example.com/api/v1/stores/123456/payment-methods/onchain/BTC/wallet")
+        .to_return(status: 200, headers: {}, body: {
+          balance: 0.91108606,
+          unconfirmedBalance: 0,
+          confirmedBalance: 0.91108606
+        }.to_json)
+    end
+
+    it "returns a formatted result for the onchain wallet balance" do
+      get api_kredits_onchain_btc_balance_path
+
+      expect(response).to have_http_status(:ok)
+
+      res = JSON.parse(response.body)
+      expect(res["balance"]).to eq(0.91108606)
+      expect(res["unconfirmed_balance"]).to eq(0)
+      expect(res["confirmed_balance"]).to eq(0.91108606)
+    end
+
+    context "upstream request error" do
+      before do
+        stub_request(:get, "http://btcpay.example.com/api/v1/stores/123456/payment-methods/onchain/BTC/wallet")
+          .to_return(status: 500, headers: {}, body: "")
+      end
+
+      it "returns a formatted error" do
+        get api_kredits_onchain_btc_balance_path
+
+        expect(response).to have_http_status(:server_error)
+
+        res = JSON.parse(response.body)
+        expect(res["error"]).not_to be_nil
+      end
+    end
+  end
+end