Investment Portfolio Sync (#974)

* Add investment portfolio models

* Add portfolio to demo data

* Setup initial tests

* Rough sketch of sync logic

* Clean up trade sync logic

* Add trade validation

* Integrate trades into sync process

test/models/account/holding/syncer_test.rb

@@ -0,0 +1,101 @@
+require "test_helper"
+
+class Account::Holding::SyncerTest < ActiveSupport::TestCase
+  include Account::EntriesTestHelper
+
+  setup do
+    @account = families(:empty).accounts.create!(name: "Test Brokerage", balance: 20000, currency: "USD", accountable: Investment.new)
+  end
+
+  test "account with no trades has no holdings" do
+    run_sync_for(@account)
+
+    assert_equal [], @account.holdings
+  end
+
+  test "can buy and sell securities" do
+    security1 = create_security("AMZN", prices: [
+      { date: 2.days.ago.to_date, price: 214 },
+      { date: 1.day.ago.to_date, price: 215 },
+      { date: Date.current, price: 216 }
+    ])
+
+    security2 = create_security("NVDA", prices: [
+      { date: 1.day.ago.to_date, price: 122 },
+      { date: Date.current, price: 124 }
+    ])
+
+    create_trade(security1, qty: 10, date: 2.days.ago.to_date) # buy 10 shares of AMZN
+
+    create_trade(security1, qty: 2, date: 1.day.ago.to_date) # buy 2 shares of AMZN
+    create_trade(security2, qty: 20, date: 1.day.ago.to_date) # buy 20 shares of NVDA
+
+    create_trade(security1, qty: -10, date: Date.current) # sell 10 shares of AMZN
+
+    expected = [
+      { symbol: "AMZN", qty: 10, price: 214, amount: 10 * 214, date: 2.days.ago.to_date },
+      { symbol: "AMZN", qty: 12, price: 215, amount: 12 * 215, date: 1.day.ago.to_date },
+      { symbol: "AMZN", qty: 2, price: 216, amount: 2 * 216, date: Date.current },
+      { symbol: "NVDA", qty: 20, price: 122, amount: 20 * 122, date: 1.day.ago.to_date },
+      { symbol: "NVDA", qty: 20, price: 124, amount: 20 * 124, date: Date.current }
+    ]
+
+    run_sync_for(@account)
+
+    assert_holdings(expected)
+  end
+
+  private
+
+    def assert_holdings(expected_holdings)
+      holdings = @account.holdings.includes(:security).to_a
+      expected_holdings.each do |expected_holding|
+        actual_holding = holdings.find { |holding| holding.security.symbol == expected_holding[:symbol] && holding.date == expected_holding[:date] }
+        date = expected_holding[:date]
+        expected_price = expected_holding[:price]
+        expected_qty = expected_holding[:qty]
+        expected_amount = expected_holding[:amount]
+        symbol = expected_holding[:symbol]
+
+        assert actual_holding, "expected #{symbol} holding on date: #{date}"
+        assert_equal expected_holding[:qty], actual_holding.qty, "expected #{expected_qty} qty for holding #{symbol} on date: #{date}"
+        assert_equal expected_holding[:amount], actual_holding.amount, "expected #{expected_amount} amount for holding #{symbol} on date: #{date}"
+        assert_equal expected_holding[:price], actual_holding.price, "expected #{expected_price} price for holding #{symbol} on date: #{date}"
+      end
+    end
+
+    def create_security(symbol, prices:)
+      isin_codes = {
+        "AMZN" => "US0231351067",
+        "NVDA" => "US67066G1040"
+      }
+
+      isin = isin_codes[symbol]
+
+      prices.each do |price|
+        Security::Price.create! isin: isin, date: price[:date], price: price[:price]
+      end
+
+      Security.create! isin: isin, symbol: symbol
+    end
+
+    def create_trade(security, qty:, date:)
+      price = Security::Price.find_by!(isin: security.isin, date: date).price
+
+      trade = Account::Trade.new \
+        qty: qty,
+        security: security,
+        price: price
+
+      @account.entries.create! \
+        name: "Trade",
+        date: date,
+        amount: qty * price,
+        currency: "USD",
+        entryable: trade
+    end
+
+    def run_sync_for(account)
+      Account::Holding::Syncer.new(account).run
+    end
+end