diff --git a/app/models/account.rb b/app/models/account.rb
index b7b11692..5440ad83 100644
--- a/app/models/account.rb
+++ b/app/models/account.rb
@@ -28,6 +28,51 @@ class Account < ApplicationRecord
 
   delegated_type :accountable, types: Accountable::TYPES, dependent: :destroy
 
+  class << self
+    def by_group(period: Period.all, currency: Money.default_currency)
+      grouped_accounts = { assets: ValueGroup.new("Assets", currency), liabilities: ValueGroup.new("Liabilities", currency) }
+
+      Accountable.by_classification.each do |classification, types|
+        types.each do |type|
+          group = grouped_accounts[classification.to_sym].add_child_group(type, currency)
+          self.where(accountable_type: type).each do |account|
+            group.add_value_node(
+              account,
+              account.balance_money.exchange_to(currency, fallback_rate: 0),
+              account.series(period: period, currency: currency)
+            )
+          end
+        end
+      end
+
+      grouped_accounts
+    end
+
+    def create_with_optional_start_balance!(attributes:, start_date: nil, start_balance: nil)
+      account = self.new(attributes.except(:accountable_type))
+      account.accountable = Accountable.from_type(attributes[:accountable_type])&.new
+
+      # Always build the initial valuation
+      account.entries.build \
+        date: Date.current,
+        amount: attributes[:balance],
+        currency: account.currency,
+        entryable: Account::Valuation.new
+
+      # Conditionally build the optional start valuation
+      if start_date.present? && start_balance.present?
+        account.entries.build \
+          date: start_date,
+          amount: start_balance,
+          currency: account.currency,
+          entryable: Account::Valuation.new
+      end
+
+      account.save!
+      account
+    end
+  end
+
   def balance_on(date)
     balances.where("date <= ?", date).order(date: :desc).first&.balance
   end
@@ -50,57 +95,11 @@ class Account < ApplicationRecord
     balance_series = balances.in_period(period).where(currency: Money::Currency.new(currency).iso_code)
 
     if balance_series.empty? && period.date_range.end == Date.current
-      converted_balance = balance_money.exchange_to(currency)
-      if converted_balance
-        TimeSeries.new([ { date: Date.current, value: converted_balance } ])
-      else
-        TimeSeries.new([])
-      end
+      TimeSeries.new([ { date: Date.current, value: balance_money.exchange_to(currency) } ])
     else
       TimeSeries.from_collection(balance_series, :balance_money)
     end
-  end
-
-  def self.by_group(period: Period.all, currency: Money.default_currency)
-    grouped_accounts = { assets: ValueGroup.new("Assets", currency), liabilities: ValueGroup.new("Liabilities", currency) }
-
-    Accountable.by_classification.each do |classification, types|
-      types.each do |type|
-        group = grouped_accounts[classification.to_sym].add_child_group(type, currency)
-        self.where(accountable_type: type).each do |account|
-          value_node = group.add_value_node(
-            account,
-            account.balance_money.exchange_to(currency) || Money.new(0, currency),
-            account.series(period: period, currency: currency)
-          )
-        end
-      end
-    end
-
-    grouped_accounts
-  end
-
-  def self.create_with_optional_start_balance!(attributes:, start_date: nil, start_balance: nil)
-    account = self.new(attributes.except(:accountable_type))
-    account.accountable = Accountable.from_type(attributes[:accountable_type])&.new
-
-    # Always build the initial valuation
-    account.entries.build \
-      date: Date.current,
-      amount: attributes[:balance],
-      currency: account.currency,
-      entryable: Account::Valuation.new
-
-    # Conditionally build the optional start valuation
-    if start_date.present? && start_balance.present?
-      account.entries.build \
-        date: start_date,
-        amount: start_balance,
-        currency: account.currency,
-        entryable: Account::Valuation.new
-    end
-
-    account.save!
-    account
+  rescue Money::ConversionError
+    TimeSeries.new([])
   end
 end
diff --git a/app/models/account/balance/calculator.rb b/app/models/account/balance/calculator.rb
index 223418e4..8b30d61f 100644
--- a/app/models/account/balance/calculator.rb
+++ b/app/models/account/balance/calculator.rb
@@ -72,10 +72,10 @@ class Account::Balance::Calculator
     end
 
     def convert_balances_to_family_currency(balances)
-      rates = ExchangeRate.get_rates(
-        account.currency,
-        account.family.currency,
-        calc_start_date..Date.current
+      rates = ExchangeRate.find_rates(
+        from: account.currency,
+        to: account.family.currency,
+        start_date: calc_start_date
       ).to_a
 
       # Abort conversion if some required rates are missing
@@ -84,8 +84,9 @@ class Account::Balance::Calculator
         return []
       end
 
-      balances.map.with_index do |balance, index|
-        converted_balance = balance[:balance] * rates[index].rate
+      balances.map do |balance|
+        rate = rates.find { |r| r.date == balance[:date] }
+        converted_balance = balance[:balance] * rate&.rate
         { date: balance[:date], balance: converted_balance, currency: account.family.currency, updated_at: Time.current }
       end
     end
diff --git a/app/models/account/entry.rb b/app/models/account/entry.rb
index 0b14ee6f..78487e5e 100644
--- a/app/models/account/entry.rb
+++ b/app/models/account/entry.rb
@@ -22,7 +22,7 @@ class Account::Entry < ApplicationRecord
       "account_entries.*",
       "account_entries.amount * COALESCE(er.rate, 1) AS converted_amount"
     )
-      .joins(sanitize_sql_array([ "LEFT JOIN exchange_rates er ON account_entries.date = er.date AND account_entries.currency = er.base_currency AND er.converted_currency = ?", currency ]))
+      .joins(sanitize_sql_array([ "LEFT JOIN exchange_rates er ON account_entries.date = er.date AND account_entries.currency = er.from_currency AND er.to_currency = ?", currency ]))
       .where("er.rate IS NOT NULL OR account_entries.currency = ?", currency)
   }
 
diff --git a/app/models/account/syncable.rb b/app/models/account/syncable.rb
index a3e09ef9..31ed1e7e 100644
--- a/app/models/account/syncable.rb
+++ b/app/models/account/syncable.rb
@@ -65,10 +65,10 @@ module Account::Syncable
     return if rate_candidates.blank?
 
     existing_rates = ExchangeRate.where(
-      base_currency: rate_candidates.map { |rc| rc[:from_currency] },
-      converted_currency: rate_candidates.map { |rc| rc[:to_currency] },
+      from_currency: rate_candidates.map { |rc| rc[:from_currency] },
+      to_currency: rate_candidates.map { |rc| rc[:to_currency] },
       date: rate_candidates.map { |rc| rc[:date] }
-    ).pluck(:base_currency, :converted_currency, :date)
+    ).pluck(:from_currency, :to_currency, :date)
 
     # Convert to a set for faster lookup
     existing_rates_set = existing_rates.map { |er| [ er[0], er[1], er[2].to_s ] }.to_set
diff --git a/app/models/concerns/providable.rb b/app/models/concerns/providable.rb
index 9b80bbf8..3f3b1aa7 100644
--- a/app/models/concerns/providable.rb
+++ b/app/models/concerns/providable.rb
@@ -7,7 +7,13 @@ module Providable
 
   class_methods do
     def exchange_rates_provider
-      Provider::Synth.new
+      api_key = ENV["SYNTH_API_KEY"]
+
+      if api_key.present?
+        Provider::Synth.new api_key
+      else
+        nil
+      end
     end
 
     def git_repository_provider
diff --git a/app/models/exchange_rate.rb b/app/models/exchange_rate.rb
index b3260b55..eb17a03a 100644
--- a/app/models/exchange_rate.rb
+++ b/app/models/exchange_rate.rb
@@ -1,29 +1,29 @@
 class ExchangeRate < ApplicationRecord
   include Provided
 
-  validates :base_currency, :converted_currency, presence: true
+  validates :from_currency, :to_currency, :date, :rate, presence: true
 
   class << self
-    def find_rate(from:, to:, date:)
-      find_by \
-        base_currency: Money::Currency.new(from).iso_code,
-        converted_currency: Money::Currency.new(to).iso_code,
+    def find_rate(from:, to:, date:, cache: true)
+      result = find_by \
+        from_currency: from,
+        to_currency: to,
         date: date
+
+      result || fetch_rate_from_provider(from:, to:, date:, cache:)
     end
 
-    def find_rate_or_fetch(from:, to:, date:)
-      find_rate(from:, to:, date:) || fetch_rate_from_provider(from:, to:, date:)&.tap(&:save!)
-    end
+    def find_rates(from:, to:, start_date:, end_date: Date.current, cache: true)
+      rates = self.where(from_currency: from, to_currency: to, date: start_date..end_date).to_a
+      all_dates = (start_date..end_date).to_a.to_set
+      existing_dates = rates.map(&:date).to_set
+      missing_dates = all_dates - existing_dates
 
-    def get_rates(from, to, dates)
-      where(base_currency: from, converted_currency: to, date: dates).order(:date)
-    end
+      if missing_dates.any?
+        rates += fetch_rates_from_provider(from:, to:, dates: missing_dates, cache:)
+      end
 
-    def convert(value:, from:, to:, date:)
-      rate = ExchangeRate.find_by(base_currency: from, converted_currency: to, date:)
-      raise "Conversion from: #{from} to: #{to} on: #{date} not found" unless rate
-
-      value * rate.rate
+      rates
     end
   end
 end
diff --git a/app/models/exchange_rate/provided.rb b/app/models/exchange_rate/provided.rb
index 8da089d7..a0e0a580 100644
--- a/app/models/exchange_rate/provided.rb
+++ b/app/models/exchange_rate/provided.rb
@@ -1,25 +1,38 @@
 module ExchangeRate::Provided
   extend ActiveSupport::Concern
+
   include Providable
 
   class_methods do
     private
-      def fetch_rate_from_provider(from:, to:, date:)
-        return nil unless exchange_rates_provider.configured?
+
+      def fetch_rates_from_provider(from:, to:, dates:, cache: false)
+        return [] unless exchange_rates_provider.present?
+
+        dates.map do |date|
+          fetch_rate_from_provider from:, to:, date:, cache:
+        end.compact
+      end
+
+      def fetch_rate_from_provider(from:, to:, date:, cache: false)
+        return nil unless exchange_rates_provider.present?
 
         response = exchange_rates_provider.fetch_exchange_rate \
-          from: Money::Currency.new(from).iso_code,
-          to: Money::Currency.new(to).iso_code,
+          from: from,
+          to: to,
           date: date
 
         if response.success?
-          ExchangeRate.new \
-            base_currency: from,
-            converted_currency: to,
+          rate = ExchangeRate.new \
+            from_currency: from,
+            to_currency: to,
             rate: response.rate,
             date: date
+
+          rate.save! if cache
+          rate
         else
-          raise response.error
+          nil
         end
       end
   end
diff --git a/app/models/family.rb b/app/models/family.rb
index 5e81e5f4..b0be8b1e 100644
--- a/app/models/family.rb
+++ b/app/models/family.rb
@@ -97,11 +97,11 @@ class Family < ApplicationRecord
   end
 
   def assets
-    Money.new(accounts.active.assets.map { |account| account.balance_money.exchange_to(currency) || 0 }.sum, currency)
+    Money.new(accounts.active.assets.map { |account| account.balance_money.exchange_to(currency, fallback_rate: 0) }.sum, currency)
   end
 
   def liabilities
-    Money.new(accounts.active.liabilities.map { |account| account.balance_money.exchange_to(currency) || 0 }.sum, currency)
+    Money.new(accounts.active.liabilities.map { |account| account.balance_money.exchange_to(currency, fallback_rate: 0) }.sum, currency)
   end
 
   def sync_accounts
diff --git a/app/models/provider/synth.rb b/app/models/provider/synth.rb
index 9966b92f..c432d63d 100644
--- a/app/models/provider/synth.rb
+++ b/app/models/provider/synth.rb
@@ -1,12 +1,8 @@
 class Provider::Synth
   include Retryable
 
-  def initialize(api_key = ENV["SYNTH_API_KEY"])
-    @api_key = api_key || ENV["SYNTH_API_KEY"]
-  end
-
-  def configured?
-    @api_key.present?
+  def initialize(api_key)
+    @api_key = api_key
   end
 
   def fetch_exchange_rate(from:, to:, date:)
diff --git a/db/migrate/20240706151026_rename_rate_fields.rb b/db/migrate/20240706151026_rename_rate_fields.rb
new file mode 100644
index 00000000..ad54304d
--- /dev/null
+++ b/db/migrate/20240706151026_rename_rate_fields.rb
@@ -0,0 +1,6 @@
+class RenameRateFields < ActiveRecord::Migration[7.2]
+  def change
+    rename_column :exchange_rates, :base_currency, :from_currency
+    rename_column :exchange_rates, :converted_currency, :to_currency
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index f64eea1f..778d5b34 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.2].define(version: 2024_06_28_104551) do
+ActiveRecord::Schema[7.2].define(version: 2024_07_06_151026) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "pgcrypto"
   enable_extension "plpgsql"
@@ -145,15 +145,15 @@ ActiveRecord::Schema[7.2].define(version: 2024_06_28_104551) do
   end
 
   create_table "exchange_rates", id: :uuid, default: -> { "gen_random_uuid()" }, force: :cascade do |t|
-    t.string "base_currency", null: false
-    t.string "converted_currency", null: false
+    t.string "from_currency", null: false
+    t.string "to_currency", null: false
     t.decimal "rate"
     t.date "date"
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
-    t.index ["base_currency", "converted_currency", "date"], name: "index_exchange_rates_on_base_converted_date_unique", unique: true
-    t.index ["base_currency"], name: "index_exchange_rates_on_base_currency"
-    t.index ["converted_currency"], name: "index_exchange_rates_on_converted_currency"
+    t.index ["from_currency", "to_currency", "date"], name: "index_exchange_rates_on_base_converted_date_unique", unique: true
+    t.index ["from_currency"], name: "index_exchange_rates_on_from_currency"
+    t.index ["to_currency"], name: "index_exchange_rates_on_to_currency"
   end
 
   create_table "families", id: :uuid, default: -> { "gen_random_uuid()" }, force: :cascade do |t|
diff --git a/lib/money.rb b/lib/money.rb
index a9d55d37..a4cd7764 100644
--- a/lib/money.rb
+++ b/lib/money.rb
@@ -2,7 +2,10 @@ class Money
   include Comparable, Arithmetic
   include ActiveModel::Validations
 
-  attr_reader :amount, :currency
+  class ConversionError < StandardError
+  end
+
+  attr_reader :amount, :currency, :store
 
   validate :source_must_be_of_known_type
 
@@ -16,20 +19,27 @@ class Money
     end
   end
 
-  def initialize(obj, currency = Money.default_currency)
+  def initialize(obj, currency = Money.default_currency, store: ExchangeRate)
     @source = obj
     @amount = obj.is_a?(Money) ? obj.amount : BigDecimal(obj.to_s)
     @currency = obj.is_a?(Money) ? obj.currency : Money::Currency.new(currency)
+    @store = store
 
     validate!
   end
 
-  # TODO: Replace with injected rate store
-  def exchange_to(other_currency, date = Date.current)
-    if currency == Money::Currency.new(other_currency)
+  def exchange_to(other_currency, date: Date.current, fallback_rate: nil)
+    iso_code = currency.iso_code
+    other_iso_code = Money::Currency.new(other_currency).iso_code
+
+    if iso_code == other_iso_code
       self
-    elsif rate = ExchangeRate.find_rate(from: currency, to: other_currency, date: date)
-      Money.new(amount * rate.rate, other_currency)
+    else
+      exchange_rate = store.find_rate(from: iso_code, to: other_iso_code, date: date)&.rate || fallback_rate
+
+      raise ConversionError.new("Couldn't find exchange rate from #{iso_code} to #{other_iso_code} on #{date}") unless exchange_rate
+
+      Money.new(amount * exchange_rate, other_iso_code)
     end
   end
 
diff --git a/lib/tasks/demo_data.rake b/lib/tasks/demo_data.rake
index cba30ad1..556ac270 100644
--- a/lib/tasks/demo_data.rake
+++ b/lib/tasks/demo_data.rake
@@ -45,8 +45,8 @@ namespace :demo_data do
     exchange_rates = (0..60).map do |days_ago|
       {
         date: Date.current - days_ago.days,
-        base_currency: "EUR",
-        converted_currency: "USD",
+        from_currency: "EUR",
+        to_currency: "USD",
         rate: rand(1.0840..1.0924).round(4)
       }
     end
@@ -54,18 +54,18 @@ namespace :demo_data do
     exchange_rates += (0..20).map do |days_ago|
       {
         date: Date.current - days_ago.days,
-        base_currency: "BTC",
-        converted_currency: "USD",
+        from_currency: "BTC",
+        to_currency: "USD",
         rate: rand(60000..65000).round(2)
       }
     end
 
     # Multi-currency account needs a few USD:EUR rates
     exchange_rates += [
-      { date: Date.current - 45.days, base_currency: "USD", converted_currency: "EUR", rate: 0.89 },
-      { date: Date.current - 34.days, base_currency: "USD", converted_currency: "EUR", rate: 0.87 },
-      { date: Date.current - 28.days, base_currency: "USD", converted_currency: "EUR", rate: 0.88 },
-      { date: Date.current - 14.days, base_currency: "USD", converted_currency: "EUR", rate: 0.86 }
+      { date: Date.current - 45.days, from_currency: "USD", to_currency: "EUR", rate: 0.89 },
+      { date: Date.current - 34.days, from_currency: "USD", to_currency: "EUR", rate: 0.87 },
+      { date: Date.current - 28.days, from_currency: "USD", to_currency: "EUR", rate: 0.88 },
+      { date: Date.current - 14.days, from_currency: "USD", to_currency: "EUR", rate: 0.86 }
     ]
 
     ExchangeRate.insert_all(exchange_rates)
diff --git a/test/fixtures/exchange_rates.yml b/test/fixtures/exchange_rates.yml
index 533d16cf..197b17d6 100644
--- a/test/fixtures/exchange_rates.yml
+++ b/test/fixtures/exchange_rates.yml
@@ -1,383 +1,11 @@
-day_31_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
+one:
+  from_currency: EUR
+  to_currency: GBP
   rate: 1.0986
-  date: <%= 31.days.ago.to_date %>
+  date: <%= Date.current %>
 
-day_30_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
+two:
+  from_currency: EUR
+  to_currency: GBP
   rate: 1.0926
-  date: <%= 30.days.ago.to_date %>
-
-day_29_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.094
-  date: <%= 29.days.ago.to_date %>
-
-day_28_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.095
-  date: <%= 28.days.ago.to_date %>
-
-day_27_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0898
-  date: <%= 27.days.ago.to_date %>
-
-day_26_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0858
-  date: <%= 26.days.ago.to_date %>
-
-day_25_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0856
-  date: <%= 25.days.ago.to_date %>
-
-day_24_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.084
-  date: <%= 24.days.ago.to_date %>
-
-day_23_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0807
-  date: <%= 23.days.ago.to_date %>
-
-day_22_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0839
-  date: <%= 22.days.ago.to_date %>
-
-day_21_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0845
-  date: <%= 21.days.ago.to_date %>
-
-day_20_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0854
-  date: <%= 20.days.ago.to_date %>
-
-day_19_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0822
-  date: <%= 19.days.ago.to_date %>
-
-day_18_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0824
-  date: <%= 18.days.ago.to_date %>
-
-day_17_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0818
-  date: <%= 17.days.ago.to_date %>
-
-day_16_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0809
-  date: <%= 16.days.ago.to_date %>
-
-day_15_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.078
-  date: <%= 15.days.ago.to_date %>
-
-day_14_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0778
-  date: <%= 14.days.ago.to_date %>
-
-day_13_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0773
-  date: <%= 13.days.ago.to_date %>
-
-day_12_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0729
-  date: <%= 12.days.ago.to_date %>
-
-day_11_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0709
-  date: <%= 11.days.ago.to_date %>
-
-day_10_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0773
-  date: <%= 10.days.ago.to_date %>
-
-day_9_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0783
-  date: <%= 9.days.ago.to_date %>
-
-day_8_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0778
-  date: <%= 8.days.ago.to_date %>
-
-day_7_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0774
-  date: <%= 7.days.ago.to_date %>
-
-day_6_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0755
-  date: <%= 6.days.ago.to_date %>
-
-day_5_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0743
-  date: <%= 5.days.ago.to_date %>
-
-day_4_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0788
-  date: <%= 4.days.ago.to_date %>
-
-day_3_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0872
-  date: <%= 3.days.ago.to_date %>
-
-day_2_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0819
-  date: <%= 2.days.ago.to_date %>
-
-day_1_ago_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0845
-  date: <%= 1.days.ago.to_date %>
-
-today_eur_to_usd:
-  base_currency: EUR
-  converted_currency: USD
-  rate: 1.0834
-  date: <%= Date.current %>
-
-day_31_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9279
-  date: <%= 31.days.ago.to_date %>
-
-day_30_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9179
-  date: <%= 30.days.ago.to_date %>
-
-day_29_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9154
-  date: <%= 29.days.ago.to_date %>
-
-day_28_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9107
-  date: <%= 28.days.ago.to_date %>
-
-day_27_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9139
-  date: <%= 27.days.ago.to_date %>
-
-day_26_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9082
-  date: <%= 26.days.ago.to_date %>
-
-day_25_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9077
-  date: <%= 25.days.ago.to_date %>
-
-day_24_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9054
-  date: <%= 24.days.ago.to_date %>
-
-day_23_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9004
-  date: <%= 23.days.ago.to_date %>
-
-day_22_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9040
-  date: <%= 22.days.ago.to_date %>
-
-day_21_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9060
-  date: <%= 21.days.ago.to_date %>
-
-day_20_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9052
-  date: <%= 20.days.ago.to_date %>
-
-day_19_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9139
-  date: <%= 19.days.ago.to_date %>
-
-day_18_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9155
-  date: <%= 18.days.ago.to_date %>
-
-day_17_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9135
-  date: <%= 17.days.ago.to_date %>
-
-day_16_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9141
-  date: <%= 16.days.ago.to_date %>
-
-day_15_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9131
-  date: <%= 15.days.ago.to_date %>
-
-day_14_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9147
-  date: <%= 14.days.ago.to_date %>
-
-day_13_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9112
-  date: <%= 13.days.ago.to_date %>
-
-day_12_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9115
-  date: <%= 12.days.ago.to_date %>
-
-day_11_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9132
-  date: <%= 11.days.ago.to_date %>
-
-day_10_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9130
-  date: <%= 10.days.ago.to_date %>
-
-day_9_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9192
-  date: <%= 9.days.ago.to_date %>
-
-day_8_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9188
-  date: <%= 8.days.ago.to_date %>
-
-day_7_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9194
-  date: <%= 7.days.ago.to_date %>
-
-day_6_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9177
-  date: <%= 6.days.ago.to_date %>
-
-day_5_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9187
-  date: <%= 5.days.ago.to_date %>
-
-day_4_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9213
-  date: <%= 4.days.ago.to_date %>
-
-day_3_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9186
-  date: <%= 3.days.ago.to_date %>
-
-day_2_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9218
-  date: <%= 2.days.ago.to_date %>
-
-day_1_ago_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9213
-  date: <%= 1.days.ago.to_date %>
-
-today_usd_to_eur:
-  base_currency: USD
-  converted_currency: EUR
-  rate: 0.9141
-  date: <%= Date.current %>
+  date: <%= 1.day.ago.to_date %>
diff --git a/test/lib/money_test.rb b/test/lib/money_test.rb
index be9b738e..e13a00e7 100644
--- a/test/lib/money_test.rb
+++ b/test/lib/money_test.rb
@@ -1,99 +1,112 @@
 require "test_helper"
+require "ostruct"
 
 class MoneyTest < ActiveSupport::TestCase
-    test "can create with default currency" do
-        value = Money.new(1000)
-        assert_equal 1000, value.amount
-    end
+  test "can create with default currency" do
+    value = Money.new(1000)
+    assert_equal 1000, value.amount
+  end
 
-    test "can create with custom currency" do
-        value1 = Money.new(1000, :EUR)
-        value2 = Money.new(1000, :eur)
-        value3 = Money.new(1000, "eur")
-        value4 = Money.new(1000, "EUR")
+  test "can create with custom currency" do
+    value1 = Money.new(1000, :EUR)
+    value2 = Money.new(1000, :eur)
+    value3 = Money.new(1000, "eur")
+    value4 = Money.new(1000, "EUR")
 
-        assert_equal value1.currency.iso_code, value2.currency.iso_code
-        assert_equal value2.currency.iso_code, value3.currency.iso_code
-        assert_equal value3.currency.iso_code, value4.currency.iso_code
-    end
+    assert_equal value1.currency.iso_code, value2.currency.iso_code
+    assert_equal value2.currency.iso_code, value3.currency.iso_code
+    assert_equal value3.currency.iso_code, value4.currency.iso_code
+  end
 
-    test "equality tests amount and currency" do
-        assert_equal Money.new(1000), Money.new(1000)
-        assert_not_equal Money.new(1000), Money.new(1001)
-        assert_not_equal Money.new(1000, :usd), Money.new(1000, :eur)
-    end
+  test "equality tests amount and currency" do
+    assert_equal Money.new(1000), Money.new(1000)
+    assert_not_equal Money.new(1000), Money.new(1001)
+    assert_not_equal Money.new(1000, :usd), Money.new(1000, :eur)
+  end
 
-    test "can compare with zero Numeric" do
-        assert_equal Money.new(0), 0
-        assert_raises(TypeError) { Money.new(1) == 1 }
-    end
+  test "can compare with zero Numeric" do
+    assert_equal Money.new(0), 0
+    assert_raises(TypeError) { Money.new(1) == 1 }
+  end
 
-    test "can negate" do
-        assert_equal (-Money.new(1000)), Money.new(-1000)
-    end
+  test "can negate" do
+    assert_equal (-Money.new(1000)), Money.new(-1000)
+  end
 
-    test "can use comparison operators" do
-        assert_operator Money.new(1000), :>, Money.new(999)
-        assert_operator Money.new(1000), :>=, Money.new(1000)
-        assert_operator Money.new(1000), :<, Money.new(1001)
-        assert_operator Money.new(1000), :<=, Money.new(1000)
-    end
+  test "can use comparison operators" do
+    assert_operator Money.new(1000), :>, Money.new(999)
+    assert_operator Money.new(1000), :>=, Money.new(1000)
+    assert_operator Money.new(1000), :<, Money.new(1001)
+    assert_operator Money.new(1000), :<=, Money.new(1000)
+  end
 
-    test "can add and subtract" do
-        assert_equal Money.new(1000) + Money.new(1000), Money.new(2000)
-        assert_equal Money.new(1000) + 1000, Money.new(2000)
-        assert_equal Money.new(1000) - Money.new(1000), Money.new(0)
-        assert_equal Money.new(1000) - 1000, Money.new(0)
-    end
+  test "can add and subtract" do
+    assert_equal Money.new(1000) + Money.new(1000), Money.new(2000)
+    assert_equal Money.new(1000) + 1000, Money.new(2000)
+    assert_equal Money.new(1000) - Money.new(1000), Money.new(0)
+    assert_equal Money.new(1000) - 1000, Money.new(0)
+  end
 
-    test "can multiply" do
-        assert_equal Money.new(1000) * 2, Money.new(2000)
-        assert_raises(TypeError) { Money.new(1000) * Money.new(2) }
-    end
+  test "can multiply" do
+    assert_equal Money.new(1000) * 2, Money.new(2000)
+    assert_raises(TypeError) { Money.new(1000) * Money.new(2) }
+  end
 
-    test "can divide" do
-        assert_equal Money.new(1000) / 2, Money.new(500)
-        assert_equal Money.new(1000) / Money.new(500), 2
-        assert_raise(TypeError) { 1000 / Money.new(2) }
-    end
+  test "can divide" do
+    assert_equal Money.new(1000) / 2, Money.new(500)
+    assert_equal Money.new(1000) / Money.new(500), 2
+    assert_raise(TypeError) { 1000 / Money.new(2) }
+  end
 
-    test "operator order does not matter" do
-        assert_equal Money.new(1000) + 1000, 1000 + Money.new(1000)
-        assert_equal Money.new(1000) - 1000, 1000 - Money.new(1000)
-        assert_equal Money.new(1000) * 2, 2 * Money.new(1000)
-    end
+  test "operator order does not matter" do
+    assert_equal Money.new(1000) + 1000, 1000 + Money.new(1000)
+    assert_equal Money.new(1000) - 1000, 1000 - Money.new(1000)
+    assert_equal Money.new(1000) * 2, 2 * Money.new(1000)
+  end
 
-    test "can get absolute value" do
-        assert_equal Money.new(1000).abs, Money.new(1000)
-        assert_equal Money.new(-1000).abs, Money.new(1000)
-    end
+  test "can get absolute value" do
+    assert_equal Money.new(1000).abs, Money.new(1000)
+    assert_equal Money.new(-1000).abs, Money.new(1000)
+  end
 
-    test "can test if zero" do
-        assert Money.new(0).zero?
-        assert_not Money.new(1000).zero?
-    end
+  test "can test if zero" do
+    assert Money.new(0).zero?
+    assert_not Money.new(1000).zero?
+  end
 
-    test "can test if negative" do
-        assert Money.new(-1000).negative?
-        assert_not Money.new(1000).negative?
-    end
+  test "can test if negative" do
+    assert Money.new(-1000).negative?
+    assert_not Money.new(1000).negative?
+  end
 
-    test "can test if positive" do
-        assert Money.new(1000).positive?
-        assert_not Money.new(-1000).positive?
-    end
+  test "can test if positive" do
+    assert Money.new(1000).positive?
+    assert_not Money.new(-1000).positive?
+  end
 
-    test "can cast to string with basic formatting" do
-        assert_equal "$1,000.90", Money.new(1000.899).format
-        assert_equal "€1.000,12", Money.new(1000.12, :eur).format
-    end
+  test "can cast to string with basic formatting" do
+    assert_equal "$1,000.90", Money.new(1000.899).format
+    assert_equal "€1.000,12", Money.new(1000.12, :eur).format
+  end
 
-    test "can exchange to another currency" do
-        er = exchange_rates(:today_usd_to_eur)
-        assert_equal Money.new(1000).exchange_to(:eur), Money.new(1000 * er.rate, :eur)
-    end
+  test "converts currency when rate available" do
+    ExchangeRate.expects(:find_rate).returns(OpenStruct.new(rate: 1.2))
 
-    test "returns nil if exchange rate not available" do
-        assert_nil Money.new(1000).exchange_to(:jpy)
+    assert_equal Money.new(1000).exchange_to(:eur), Money.new(1000 * 1.2, :eur)
+  end
+
+  test "raises when no conversion rate available and no fallback rate provided" do
+    ExchangeRate.expects(:find_rate).returns(nil)
+
+    assert_raises Money::ConversionError do
+      Money.new(1000).exchange_to(:jpy)
     end
+  end
+
+  test "converts currency with a fallback rate" do
+    ExchangeRate.expects(:find_rate).returns(nil).twice
+
+    assert_equal 0, Money.new(1000).exchange_to(:jpy, fallback_rate: 0)
+    assert_equal Money.new(1000, :jpy), Money.new(1000, :usd).exchange_to(:jpy, fallback_rate: 1)
+  end
 end
diff --git a/test/models/account/balance/calculator_test.rb b/test/models/account/balance/calculator_test.rb
index 88d728ff..bac5d4c3 100644
--- a/test/models/account/balance/calculator_test.rb
+++ b/test/models/account/balance/calculator_test.rb
@@ -25,6 +25,17 @@ class Account::Balance::CalculatorTest < ActiveSupport::TestCase
   end
 
   test "syncs foreign checking account balances" do
+    required_exchange_rates_for_sync = [
+      1.0834, 1.0845, 1.0819, 1.0872, 1.0788, 1.0743, 1.0755, 1.0774,
+      1.0778, 1.0783, 1.0773, 1.0709, 1.0729, 1.0773, 1.0778, 1.078,
+      1.0809, 1.0818, 1.0824, 1.0822, 1.0854, 1.0845, 1.0839, 1.0807,
+      1.084, 1.0856, 1.0858, 1.0898, 1.095, 1.094, 1.0926, 1.0986
+    ]
+
+    required_exchange_rates_for_sync.each_with_index do |exchange_rate, idx|
+      ExchangeRate.create! date: idx.days.ago.to_date, from_currency: "EUR", to_currency: "USD", rate: exchange_rate
+    end
+
     # Foreign accounts will generate balances for all currencies
     expected_usd_balances = get_expected_balances_for(:eur_checking_usd)
     expected_eur_balances = get_expected_balances_for(:eur_checking_eur)
@@ -38,6 +49,13 @@ class Account::Balance::CalculatorTest < ActiveSupport::TestCase
   end
 
   test "syncs multi-currency checking account balances" do
+    required_exchange_rates_for_sync = [
+      { from_currency: "EUR", to_currency: "USD", date: 4.days.ago.to_date, rate: 1.0788 },
+      { from_currency: "EUR", to_currency: "USD", date: 19.days.ago.to_date, rate: 1.0822 }
+    ]
+
+    ExchangeRate.insert_all(required_exchange_rates_for_sync)
+
     expected_balances = get_expected_balances_for(:multi_currency)
     assert_account_balances calculated_balances_for(:multi_currency), expected_balances
   end
diff --git a/test/models/account/syncable_test.rb b/test/models/account/syncable_test.rb
index 30f686f1..6eb8c808 100644
--- a/test/models/account/syncable_test.rb
+++ b/test/models/account/syncable_test.rb
@@ -18,15 +18,14 @@ class Account::SyncableTest < ActiveSupport::TestCase
     assert_equal 32, @account.balances.count
   end
 
-  test "syncs foreign currency account" do
-    account = accounts(:eur_checking)
-    account.sync
-    assert_equal "ok", account.status
-    assert_equal 32, account.balances.where(currency: "USD").count
-    assert_equal 32, account.balances.where(currency: "EUR").count
-  end
-
   test "syncs multi currency account" do
+    required_exchange_rates_for_sync = [
+      { from_currency: "EUR", to_currency: "USD", date: 4.days.ago.to_date, rate: 1.0788 },
+      { from_currency: "EUR", to_currency: "USD", date: 19.days.ago.to_date, rate: 1.0822 }
+    ]
+
+    ExchangeRate.insert_all(required_exchange_rates_for_sync)
+
     account = accounts(:multi_currency)
     account.sync
     assert_equal "ok", account.status
@@ -91,6 +90,17 @@ class Account::SyncableTest < ActiveSupport::TestCase
   end
 
   test "foreign currency account has balances in each currency after syncing" do
+    required_exchange_rates_for_sync = [
+      1.0834, 1.0845, 1.0819, 1.0872, 1.0788, 1.0743, 1.0755, 1.0774,
+      1.0778, 1.0783, 1.0773, 1.0709, 1.0729, 1.0773, 1.0778, 1.078,
+      1.0809, 1.0818, 1.0824, 1.0822, 1.0854, 1.0845, 1.0839, 1.0807,
+      1.084, 1.0856, 1.0858, 1.0898, 1.095, 1.094, 1.0926, 1.0986
+    ]
+
+    required_exchange_rates_for_sync.each_with_index do |exchange_rate, idx|
+      ExchangeRate.create! date: idx.days.ago.to_date, from_currency: "EUR", to_currency: "USD", rate: exchange_rate
+    end
+
     account = accounts(:eur_checking)
     account.sync
 
diff --git a/test/models/exchange_rate_test.rb b/test/models/exchange_rate_test.rb
index ac2ddf55..c2398be9 100644
--- a/test/models/exchange_rate_test.rb
+++ b/test/models/exchange_rate_test.rb
@@ -1,50 +1,95 @@
 require "test_helper"
 require "ostruct"
+
 class ExchangeRateTest < ActiveSupport::TestCase
-  test "find rate in db" do
-    assert_equal exchange_rates(:day_29_ago_eur_to_usd),
-      ExchangeRate.find_rate_or_fetch(from: "EUR", to: "USD", date: 29.days.ago.to_date)
+  setup do
+    @provider = mock
+
+    ExchangeRate.stubs(:exchange_rates_provider).returns(@provider)
   end
 
-  test "fetch rate from provider when it's not found in db" do
-    with_env_overrides SYNTH_API_KEY: "true" do
-      ExchangeRate
-        .expects(:fetch_rate_from_provider)
-        .returns(ExchangeRate.new(base_currency: "USD", converted_currency: "MXN", rate: 1.0, date: Date.current))
+  test "exchange rate provider nil if no api key configured" do
+    ExchangeRate.unstub(:exchange_rates_provider)
 
-      ExchangeRate.find_rate_or_fetch from: "USD", to: "MXN", date: Date.current
+    with_env_overrides SYNTH_API_KEY: nil do
+      assert_nil ExchangeRate.exchange_rates_provider
     end
   end
 
-  test "provided rates are saved to the db" do
-    with_env_overrides SYNTH_API_KEY: "true" do
-      VCR.use_cassette "synth_exchange_rate" do
-        assert_difference "ExchangeRate.count", 1 do
-          ExchangeRate.find_rate_or_fetch from: "USD", to: "MXN", date: Date.current
-        end
-      end
+  test "finds single rate in DB" do
+    @provider.expects(:fetch_exchange_rate).never
+
+    rate = exchange_rates(:one)
+
+    assert_equal exchange_rates(:one), ExchangeRate.find_rate(from: rate.from_currency, to: rate.to_currency, date: rate.date)
+  end
+
+  test "finds single rate from provider and caches to DB" do
+    expected_rate = 1.21
+    @provider.expects(:fetch_exchange_rate).once.returns(OpenStruct.new(success?: true, rate: expected_rate))
+
+    fetched_rate = ExchangeRate.find_rate(from: "USD", to: "EUR", date: Date.current, cache: true)
+    refetched_rate = ExchangeRate.find_rate(from: "USD", to: "EUR", date: Date.current, cache: true)
+
+    assert_equal expected_rate, fetched_rate.rate
+    assert_equal expected_rate, refetched_rate.rate
+  end
+
+  test "nil if rate is not found in DB and provider throws an error" do
+    @provider.expects(:fetch_exchange_rate).with(from: "USD", to: "EUR", date: Date.current).once.returns(OpenStruct.new(success?: false))
+
+    assert_nil ExchangeRate.find_rate(from: "USD", to: "EUR", date: Date.current)
+  end
+
+  test "nil if rate is not found in DB and provider is disabled" do
+    ExchangeRate.unstub(:exchange_rates_provider)
+
+    with_env_overrides SYNTH_API_KEY: nil do
+      assert_nil ExchangeRate.find_rate(from: "USD", to: "EUR", date: Date.current)
     end
   end
 
-  test "retrying, then raising on provider error" do
-    with_env_overrides SYNTH_API_KEY: "true" do
-      Faraday.expects(:get).returns(OpenStruct.new(success?: false)).times(3)
+  test "finds multiple rates in DB" do
+    @provider.expects(:fetch_exchange_rate).never
 
-      error = assert_raises Provider::Base::ProviderError do
-        ExchangeRate.find_rate_or_fetch from: "USD", to: "MXN", date: Date.current
-      end
+    rate1 = exchange_rates(:one) # EUR -> GBP, today
+    rate2 = exchange_rates(:two) # EUR -> GBP, yesterday
 
-      assert_match "Failed to fetch exchange rate from Provider::Synth", error.message
-    end
+    fetched_rates = ExchangeRate.find_rates(from: rate1.from_currency, to: rate1.to_currency, start_date: 1.day.ago.to_date).sort_by(&:date)
+
+    assert_equal rate1, fetched_rates[1]
+    assert_equal rate2, fetched_rates[0]
   end
 
-  test "retrying, then raising on network error" do
-    with_env_overrides SYNTH_API_KEY: "true" do
-      Faraday.expects(:get).raises(Faraday::TimeoutError).times(3)
+  test "finds multiple rates from provider and caches to DB" do
+    @provider.expects(:fetch_exchange_rate).with(from: "EUR", to: "USD", date: 1.day.ago.to_date).returns(OpenStruct.new(success?: true, rate: 1.1)).once
+    @provider.expects(:fetch_exchange_rate).with(from: "EUR", to: "USD", date: Date.current).returns(OpenStruct.new(success?: true, rate: 1.2)).once
 
-      assert_raises Faraday::TimeoutError do
-        ExchangeRate.find_rate_or_fetch from: "USD", to: "MXN", date: Date.current
-      end
+    fetched_rates = ExchangeRate.find_rates(from: "EUR", to: "USD", start_date: 1.day.ago.to_date, cache: true)
+    refetched_rates = ExchangeRate.find_rates(from: "EUR", to: "USD", start_date: 1.day.ago.to_date)
+
+    assert_equal [ 1.1, 1.2 ], fetched_rates.sort_by(&:date).map(&:rate)
+    assert_equal [ 1.1, 1.2 ], refetched_rates.sort_by(&:date).map(&:rate)
+  end
+
+  test "finds missing db rates from provider and appends to results" do
+    @provider.expects(:fetch_exchange_rate).with(from: "EUR", to: "GBP", date: 2.days.ago.to_date).returns(OpenStruct.new(success?: true, rate: 1.1)).once
+
+    rate1 = exchange_rates(:one) # EUR -> GBP, today
+    rate2 = exchange_rates(:two) # EUR -> GBP, yesterday
+
+    fetched_rates = ExchangeRate.find_rates(from: "EUR", to: "GBP", start_date: 2.days.ago.to_date, cache: true)
+    refetched_rates = ExchangeRate.find_rates(from: "EUR", to: "GBP", start_date: 2.days.ago.to_date)
+
+    assert_equal [ 1.1, rate2.rate, rate1.rate ], fetched_rates.sort_by(&:date).map(&:rate)
+    assert_equal [ 1.1, rate2.rate, rate1.rate ], refetched_rates.sort_by(&:date).map(&:rate)
+  end
+
+  test "returns empty array if no rates found in DB or provider" do
+    ExchangeRate.unstub(:exchange_rates_provider)
+
+    with_env_overrides SYNTH_API_KEY: nil do
+      assert_equal [], ExchangeRate.find_rates(from: "USD", to: "JPY", start_date: 10.days.ago.to_date)
     end
   end
 end
diff --git a/test/models/family_test.rb b/test/models/family_test.rb
index 96eb2cdc..9efc06ed 100644
--- a/test/models/family_test.rb
+++ b/test/models/family_test.rb
@@ -6,6 +6,18 @@ class FamilyTest < ActiveSupport::TestCase
 
   def setup
     @family = families(:dylan_family)
+
+    required_exchange_rates_for_family = [
+      1.0834, 1.0845, 1.0819, 1.0872, 1.0788, 1.0743, 1.0755, 1.0774,
+      1.0778, 1.0783, 1.0773, 1.0709, 1.0729, 1.0773, 1.0778, 1.078,
+      1.0809, 1.0818, 1.0824, 1.0822, 1.0854, 1.0845, 1.0839, 1.0807,
+      1.084, 1.0856, 1.0858, 1.0898, 1.095, 1.094, 1.0926, 1.0986
+    ]
+
+    required_exchange_rates_for_family.each_with_index do |exchange_rate, idx|
+      ExchangeRate.create! date: idx.days.ago.to_date, from_currency: "EUR", to_currency: "USD", rate: exchange_rate
+    end
+
     @family.accounts.each do |account|
       account.sync
     end
diff --git a/test/models/provider/synth_test.rb b/test/models/provider/synth_test.rb
index 74f98f07..5559e7cb 100644
--- a/test/models/provider/synth_test.rb
+++ b/test/models/provider/synth_test.rb
@@ -1,9 +1,26 @@
 require "test_helper"
+require "ostruct"
 
 class Provider::SynthTest < ActiveSupport::TestCase
   include ExchangeRateProviderInterfaceTest
 
   setup do
-    @subject = Provider::Synth.new
+    @subject = @synth = Provider::Synth.new("fookey")
+  end
+
+  test "retries then provides failed response" do
+    Faraday.expects(:get).returns(OpenStruct.new(success?: false)).times(3)
+
+    response = @synth.fetch_exchange_rate from: "USD", to: "MXN", date: Date.current
+
+    assert_match "Failed to fetch exchange rate from Provider::Synth", response.error.message
+  end
+
+  test "retrying, then raising on network error" do
+    Faraday.expects(:get).raises(Faraday::TimeoutError).times(3)
+
+    assert_raises Faraday::TimeoutError do
+      @synth.fetch_exchange_rate from: "USD", to: "MXN", date: Date.current
+    end
   end
 end