Add tests and refactor for Simplefin holdings import and processing

- Introduced tests for importer post-import logic and `SimplefinHoldingsApplyJob`.
- Refactored `ProviderImportAdapter` to improve holding resolution strategy.
- Added handling of investment and crypto holdings in importer with debounce logic for job enqueuing.
- Updated rake task to use `SimplefinHoldingsApplyJob` for holding materialization.

test/jobs/simplefin_holdings_apply_job_test.rb

@@ -0,0 +1,63 @@
+require "test_helper"
+
+class SimplefinHoldingsApplyJobTest < ActiveSupport::TestCase
+  setup do
+    @family = families(:dylan_family)
+    @item = SimplefinItem.create!(family: @family, name: "SF", access_url: "https://example.com/x")
+
+    @account = accounts(:investment)
+
+    # Link SFA to existing investment account via legacy association for simplicity
+    @sfa = @item.simplefin_accounts.create!(
+      name: "Invest",
+      account_id: "sf_invest_1",
+      currency: "USD",
+      account_type: "investment",
+      current_balance: 10_000
+    )
+    @account.update!(simplefin_account_id: @sfa.id)
+  end
+
+  test "materializes holdings from raw_holdings_payload and is idempotent" do
+    # Two holdings: one AAPL (existing security), one NEWCO (should be created)
+    @sfa.update!(
+      raw_holdings_payload: [
+        {
+          "id" => "h1",
+          "symbol" => "AAPL",
+          "quantity" => 10,
+          "market_value" => 2000,
+          "currency" => "USD",
+          "as_of" => (Date.current - 2.days).to_s
+        },
+        {
+          "id" => "h2",
+          "symbol" => "NEWCO",
+          "quantity" => 5,
+          "market_value" => 500,
+          "currency" => "USD",
+          "as_of" => Date.current.to_s
+        }
+      ]
+    )
+
+    assert_difference "Holding.where(account: @account).count", 2 do
+      SimplefinHoldingsApplyJob.perform_now(@sfa.id)
+    end
+
+
+    # Running again should not create duplicates (external_id uniqueness)
+    assert_no_difference "Holding.where(account: @account).count" do
+      SimplefinHoldingsApplyJob.perform_now(@sfa.id)
+    end
+
+    holdings = @account.holdings.order(:external_id)
+    aapl = holdings.find { |h| h.security.ticker == "AAPL" }
+    refute_nil aapl
+    assert_equal 10, aapl.qty
+    assert_equal Money.new(2000, "USD"), aapl.amount_money
+
+    newco_sec = Security.find_by(ticker: "NEWCO")
+    refute_nil newco_sec, "should create NEWCO security via resolver when missing"
+  end
+end

test/models/simplefin_item/importer_post_import_test.rb

@@ -0,0 +1,74 @@
+require "test_helper"
+
+class SimplefinItem::ImporterPostImportTest < ActiveSupport::TestCase
+  setup do
+    @family = families(:dylan_family)
+    @item = SimplefinItem.create!(family: @family, name: "SF Conn", access_url: "https://example.com/access")
+    @sync = Sync.create!(syncable: @item)
+  end
+
+  test "credit account import updates available_credit when available-balance provided" do
+    credit_acct = accounts(:credit_card)
+
+    sfa = @item.simplefin_accounts.create!(
+      name: "CC",
+      account_id: "sf_cc_1",
+      currency: "USD",
+      account_type: "credit",
+      available_balance: 0
+    )
+    # Link via legacy association
+    credit_acct.update!(simplefin_account_id: sfa.id)
+
+    importer = SimplefinItem::Importer.new(@item, simplefin_provider: mock(), sync: @sync)
+
+    account_data = {
+      id: sfa.account_id,
+      name: "CC",
+      balance: -1200.0, # liabilities often negative from provider
+      currency: "USD",
+      "available-balance": 5000.0
+    }
+
+    # Call private method for focused unit test
+    importer.send(:import_account, account_data)
+
+    assert_equal 5000.0, credit_acct.reload.credit_card.available_credit
+  end
+
+  test "investment import recalculates cash_balance when holdings payload changes" do
+    invest_acct = accounts(:investment)
+
+    sfa = @item.simplefin_accounts.create!(
+      name: "Invest",
+      account_id: "sf_inv_1",
+      currency: "USD",
+      account_type: "investment",
+      current_balance: 0
+    )
+    invest_acct.update!(simplefin_account_id: sfa.id)
+
+    importer = SimplefinItem::Importer.new(@item, simplefin_provider: mock(), sync: @sync)
+
+    holdings = [
+      { "id" => "h1", "symbol" => "AAPL", "quantity" => 10, "market_value" => 2000, "currency" => "USD", "as_of" => Date.current.to_s },
+      { "id" => "h2", "symbol" => "MSFT", "quantity" => 20, "market_value" => 4000, "currency" => "USD", "as_of" => Date.current.to_s }
+    ]
+
+    account_data = {
+      id: sfa.account_id,
+      name: "Invest",
+      balance: 10000.0,
+      currency: "USD",
+      holdings: holdings
+    }
+
+    # Prevent the job from running in this unit test; we only care about cash balance recompute
+    SimplefinHoldingsApplyJob.expects(:perform_later).once
+
+    importer.send(:import_account, account_data)
+
+    # Cash balance should be total balance (10_000) minus market_value sum (6_000) = 4_000
+    assert_equal 4000.0, invest_acct.reload.cash_balance
+  end
+end