sure/test/models/insight/body_writer_test.rb

require "test_helper"
require "ostruct"

class Insight::BodyWriterTest < ActiveSupport::TestCase
  setup do
    @family = families(:dylan_family)
  end

  test "writes the template body when nobody in the family has AI enabled" do
    @family.users.update_all(ai_enabled: false)
    Provider::Registry.expects(:preferred_llm_provider).never

    body = Insight::BodyWriter.new(@family).write(generated_insight)

    assert_equal I18n.t("insights.templates.idle_cash", **generated_insight.facts.symbolize_keys), body
  end

  test "uses LLM prose when a user has opted in and a provider is configured" do
    Provider::Registry.stubs(:preferred_llm_provider).returns(FakeLlmProvider.new("Narrated body."))

    body = Insight::BodyWriter.new(@family).write(generated_insight)

    assert_equal "Narrated body.", body
  end

  test "falls back to the template and captures a debug log when the LLM call fails" do
    provider = FakeLlmProvider.new("unused")
    provider.stubs(:chat_response).raises(StandardError.new("boom"))
    Provider::Registry.stubs(:preferred_llm_provider).returns(provider)

    body = nil
    assert_difference "DebugLogEntry.count", 1 do
      body = Insight::BodyWriter.new(@family).write(generated_insight)
    end

    assert_equal I18n.t("insights.templates.idle_cash", **generated_insight.facts.symbolize_keys), body
  end

  test "every template key interpolates with its generator's facts" do
    TEMPLATE_FACTS.each do |template_key, facts|
      body = I18n.t!("insights.templates.#{template_key}", **facts)

      assert body.present?, "insights.templates.#{template_key} produced a blank body"
    end
  end

  private
    # One representative facts hash per template a generator can emit. Keeps
    # the i18n templates honest: a renamed key or interpolation raises here
    # instead of shipping "translation missing" as a stored body in production.
    TEMPLATE_FACTS = {
      "spending_anomaly.above" => { category: "Food & Drink", deviation_pct: 38, projected_spend: "$612.00", baseline_spend: "$443.00" },
      "spending_anomaly.below" => { category: "Food & Drink", deviation_pct: 30, projected_spend: "$310.00", baseline_spend: "$443.00" },
      "cash_flow_warning.low" => { projected_low: "$320.00", projected_low_date: "Jul 28, 2026", current_balance: "$1,200.00", horizon_days: 30 },
      "cash_flow_warning.negative" => { projected_low: "-$412.00", projected_low_date: "Jul 28, 2026", current_balance: "$800.00", horizon_days: 30 },
      "net_worth_milestone" => { milestone: "$500,000", net_worth: "$878,578.56" },
      "subscription_audit" => { name: "Netflix", amount: "$15.49", days_overdue: 48, expected_on: "May 24, 2026" },
      "savings_rate_change.up" => { month: "June", current_rate: 32.5, previous_rate: 20.1, change_pp: 12.4 },
      "savings_rate_change.down" => { month: "June", current_rate: "12.1", previous_rate: "45.2", change_pp: 33.1 },
      "savings_rate_change.down_negative" => { month: "June", current_rate: "−5.4", previous_rate: "45.2", change_pp: 50.6 },
      "idle_cash" => { account: "Emergency fund", balance: "$28,400.00", idle_days: 60 },
      "budget_at_risk.over" => { categories: "Food & Drink and Travel", count: 2, budget_spent_pct: 84 },
      "budget_at_risk.near" => { categories: "Shopping", count: 1, budget_spent_pct: 72 },
      "budget_on_track" => { spent: "$2,948.00", budgeted: "$5,200.00", budget_spent_pct: 57 }
    }.freeze

    class FakeLlmProvider
      def self.effective_model
        "fake-model"
      end

      def initialize(body)
        @body = body
      end

      def chat_response(*, **)
        OpenStruct.new(
          success?: true,
          data: OpenStruct.new(messages: [ OpenStruct.new(id: "1", output_text: @body) ])
        )
      end
    end

    def generated_insight
      @generated_insight ||= Insight::Generator::GeneratedInsight.new(
        insight_type: "idle_cash",
        priority: "low",
        title: "Idle cash in Emergency fund",
        template_key: "idle_cash",
        facts: { account: "Emergency fund", balance: "$28,400.00", idle_days: 60 },
        metadata: { account_id: "acct", balance: 28_400.0 },
        currency: "USD",
        period_start: nil,
        period_end: nil,
        dedup_key: "idle_cash:acct:2026-07"
      )
    end
end