Multi-Currency Part 2 (#543)

* Support all currencies, handle outside DB

* Remove currencies from seed

* Fix account balance namespace

* Set default currency on authentication

* Cache currency instances

* Implement multi-currency syncs with tests

* Series fallback, passing tests

* Fix conflicts

* Make value group concrete class that works with currency values

* Fix migration conflict

* Update tests to expect multi-currency results

* Update account list to use group method

* Namespace updates

* Fetch unknown exchange rates from API

* Fix date range bug

* Ensure demo data works without external API

* Enforce cascades only at DB level

test/models/account/balance/calculator_test.rb

@@ -0,0 +1,98 @@
+require "test_helper"
+require "csv"
+
+class Account::Balance::CalculatorTest < ActiveSupport::TestCase
+    # See: https://docs.google.com/spreadsheets/d/18LN5N-VLq4b49Mq1fNwF7_eBiHSQB46qQduRtdAEN98/edit?usp=sharing
+    setup do
+        @expected_balances = CSV.read("test/fixtures/account/expected_balances.csv", headers: true).map do |row|
+            {
+                "date" => (Date.current + row["date_offset"].to_i.days).to_date,
+                "collectable" => row["collectable"],
+                "checking" => row["checking"],
+                "savings_with_valuation_overrides" => row["savings_with_valuation_overrides"],
+                "credit_card" => row["credit_card"],
+                "multi_currency" => row["multi_currency"],
+
+                # Balances should be calculated for all currencies of an account
+                "eur_checking_eur" => row["eur_checking_eur"],
+                "eur_checking_usd" => row["eur_checking_usd"]
+            }
+        end
+    end
+
+    test "syncs account with only valuations" do
+        account = accounts(:collectable)
+
+        calculator = Account::Balance::Calculator.new(account)
+        calculator.calculate
+
+        expected = @expected_balances.map { |row| row["collectable"].to_d }
+        actual = calculator.daily_balances.map { |b| b[:balance] }
+
+        assert_equal expected, actual
+    end
+
+    test "syncs account with only transactions" do
+        account = accounts(:checking)
+
+        calculator = Account::Balance::Calculator.new(account)
+        calculator.calculate
+
+        expected = @expected_balances.map { |row| row["checking"].to_d }
+        actual = calculator.daily_balances.map { |b| b[:balance] }
+
+        assert_equal expected, actual
+    end
+
+    test "syncs account with both valuations and transactions" do
+        account = accounts(:savings_with_valuation_overrides)
+
+        calculator = Account::Balance::Calculator.new(account)
+        calculator.calculate
+
+        expected = @expected_balances.map { |row| row["savings_with_valuation_overrides"].to_d }
+        actual = calculator.daily_balances.map { |b| b[:balance] }
+
+        assert_equal expected, actual
+    end
+
+    test "syncs liability account" do
+        account = accounts(:credit_card)
+
+        calculator = Account::Balance::Calculator.new(account)
+        calculator.calculate
+
+        expected = @expected_balances.map { |row| row["credit_card"].to_d }
+        actual = calculator.daily_balances.map { |b| b[:balance] }
+
+        assert_equal expected, actual
+    end
+
+    test "syncs foreign currency account" do
+        account = accounts(:eur_checking)
+        calculator = Account::Balance::Calculator.new(account)
+        calculator.calculate
+
+        # Calculator should calculate balances in both account and family currency
+        expected_eur_balances = @expected_balances.map { |row| row["eur_checking_eur"].to_d }
+        expected_usd_balances = @expected_balances.map { |row| row["eur_checking_usd"].to_d }
+
+        actual_eur_balances = calculator.daily_balances.select { |b| b[:currency] == "EUR" }.sort_by { |b| b[:date] }.map { |b| b[:balance] }
+        actual_usd_balances = calculator.daily_balances.select { |b| b[:currency] == "USD" }.sort_by { |b| b[:date] }.map { |b| b[:balance] }
+
+        assert_equal expected_eur_balances, actual_eur_balances
+        assert_equal expected_usd_balances, actual_usd_balances
+    end
+
+    test "syncs multi currency account" do
+        account = accounts(:multi_currency)
+        calculator = Account::Balance::Calculator.new(account)
+        calculator.calculate
+
+        expected_balances = @expected_balances.map { |row| row["multi_currency"].to_d }
+
+        actual_balances = calculator.daily_balances.map { |b| b[:balance] }
+
+        assert_equal expected_balances, actual_balances
+    end
+end