Add tests for SnapTrade error handling and refine unlink behavior (#931)

- Introduced new tests to cover SnapTrade decryption and connection errors in `SnaptradeItemsControllerTest`.
- Updated error messages for improved user clarity.
- Modified `unlink` functionality to preserve `SnaptradeAccount` records while ensuring proper detachment of associated holdings.

test/controllers/accounts_controller_test.rb

@@ -165,6 +165,51 @@ class AccountsControllerTest < ActionDispatch::IntegrationTest
     assert_redirected_to account_url(@account)
     assert_equal "Account is already linked to a provider", flash[:alert]
   end
+
+  test "unlink preserves SnaptradeAccount record" do
+    snaptrade_account = snaptrade_accounts(:fidelity_401k)
+    investment = accounts(:investment)
+    AccountProvider.create!(account: investment, provider: snaptrade_account)
+    investment.reload
+
+    assert investment.linked?
+
+    delete unlink_account_url(investment)
+    investment.reload
+
+    assert_not investment.linked?
+    assert_redirected_to accounts_path
+    # SnaptradeAccount should still exist (not destroyed)
+    assert SnaptradeAccount.exists?(snaptrade_account.id), "SnaptradeAccount should be preserved after unlink"
+    # But AccountProvider should be gone
+    assert_not AccountProvider.exists?(provider_type: "SnaptradeAccount", provider_id: snaptrade_account.id)
+  end
+
+  test "unlink does not enqueue SnapTrade cleanup job" do
+    snaptrade_account = snaptrade_accounts(:fidelity_401k)
+    investment = accounts(:investment)
+    AccountProvider.create!(account: investment, provider: snaptrade_account)
+    investment.reload
+
+    assert_no_enqueued_jobs(only: SnaptradeConnectionCleanupJob) do
+      delete unlink_account_url(investment)
+    end
+  end
+
+  test "unlink detaches holdings from SnapTrade provider" do
+    snaptrade_account = snaptrade_accounts(:fidelity_401k)
+    investment = accounts(:investment)
+    ap = AccountProvider.create!(account: investment, provider: snaptrade_account)
+
+    # Assign a holding to this provider
+    holding = holdings(:one)
+    holding.update!(account_provider: ap)
+
+    delete unlink_account_url(investment)
+    holding.reload
+
+    assert_nil holding.account_provider_id, "Holding should be detached from provider after unlink"
+  end
 end
 
 class AccountsControllerSimplefinCtaTest < ActionDispatch::IntegrationTest

test/controllers/snaptrade_items_controller_test.rb

@@ -0,0 +1,41 @@
+require "test_helper"
+
+class SnaptradeItemsControllerTest < ActionDispatch::IntegrationTest
+  setup do
+    sign_in @user = users(:family_admin)
+    @snaptrade_item = snaptrade_items(:configured_item)
+  end
+
+  test "connect handles decryption error gracefully" do
+    SnaptradeItem.any_instance
+      .stubs(:user_registered?)
+      .raises(ActiveRecord::Encryption::Errors::Decryption.new("cannot decrypt"))
+
+    get connect_snaptrade_item_url(@snaptrade_item)
+
+    assert_redirected_to settings_providers_path
+    assert_match(/Unable to read SnapTrade credentials/, flash[:alert])
+  end
+
+  test "connect handles general error gracefully" do
+    SnaptradeItem.any_instance
+      .stubs(:user_registered?)
+      .raises(StandardError.new("something broke"))
+
+    get connect_snaptrade_item_url(@snaptrade_item)
+
+    assert_redirected_to settings_providers_path
+    assert_match(/Failed to connect/, flash[:alert])
+  end
+
+  test "connect redirects to portal when successful" do
+    portal_url = "https://app.snaptrade.com/portal/test123"
+
+    SnaptradeItem.any_instance.stubs(:user_registered?).returns(true)
+    SnaptradeItem.any_instance.stubs(:connection_portal_url).returns(portal_url)
+
+    get connect_snaptrade_item_url(@snaptrade_item)
+
+    assert_redirected_to portal_url
+  end
+end