Basic Portfolio Views (#1000)

* Add holdings tab to account view

* Basic portfolio UI

* Cleanup

* Handle missing holding data

* Remove synced at (implemented in separate pr)

* translations

* Tweak post sync streams

* Remove stale methods from merge conflict

test/models/account/holding_test.rb

@@ -1,7 +1,71 @@
 require "test_helper"
+require "ostruct"
 
 class Account::HoldingTest < ActiveSupport::TestCase
-  # test "the truth" do
-  #   assert true
-  # end
+  include Account::EntriesTestHelper, SecuritiesTestHelper
+
+  setup do
+    @account = families(:empty).accounts.create!(name: "Test Brokerage", balance: 20000, currency: "USD", accountable: Investment.new)
+
+    # Current day holding instances
+    @amzn, @nvda = load_holdings
+  end
+
+  test "calculates portfolio weight" do
+    expected_portfolio_value = 6960.0
+    expected_amzn_weight = 3240.0 / expected_portfolio_value * 100
+    expected_nvda_weight = 3720.0 / expected_portfolio_value * 100
+
+    assert_in_delta expected_amzn_weight, @amzn.weight, 0.001
+    assert_in_delta expected_nvda_weight, @nvda.weight, 0.001
+  end
+
+  test "calculates simple average cost basis" do
+    assert_equal Money.new((212.0 + 216.0) / 2), @amzn.avg_cost
+    assert_equal Money.new((128.0 + 124.0) / 2), @nvda.avg_cost
+  end
+
+  test "calculates total return trend" do
+    # Gained $30, or 0.93%
+    assert_equal Money.new(30), @amzn.trend.value
+    assert_in_delta 0.9, @amzn.trend.percent, 0.001
+
+    # Lost $60, or -1.59%
+    assert_equal Money.new(-60), @nvda.trend.value
+    assert_in_delta -1.6, @nvda.trend.percent, 0.001
+  end
+
+  private
+
+    def load_holdings
+      security1 = create_security("AMZN", prices: [
+        { date: 1.day.ago.to_date, price: 212.00 },
+        { date: Date.current, price: 216.00 }
+      ])
+
+      security2 = create_security("NVDA", prices: [
+        { date: 1.day.ago.to_date, price: 128.00 },
+        { date: Date.current, price: 124.00 }
+      ])
+
+      create_holding(security1, 1.day.ago.to_date, 10)
+      amzn = create_holding(security1, Date.current, 15)
+
+      create_holding(security2, 1.day.ago.to_date, 5)
+      nvda = create_holding(security2, Date.current, 30)
+
+      [ amzn, nvda ]
+    end
+
+    def create_holding(security, date, qty)
+      price = Security::Price.find_by(date: date, isin: security.isin).price
+
+      @account.holdings.create! \
+        date: date,
+        security: security,
+        qty: qty,
+        price: price,
+        amount: qty * price,
+        currency: "USD"
+    end
 end