FIX providers invalid currency handling (#589)

test/models/concerns/currency_normalizable_test.rb

@@ -0,0 +1,69 @@
+require "test_helper"
+
+class CurrencyNormalizableTest < ActiveSupport::TestCase
+  # Create a test class that includes the concern
+  class TestClass
+    include CurrencyNormalizable
+
+    # Expose private method for testing
+    def test_parse_currency(value)
+      parse_currency(value)
+    end
+  end
+
+  setup do
+    @parser = TestClass.new
+  end
+
+  test "parse_currency normalizes lowercase to uppercase" do
+    assert_equal "USD", @parser.test_parse_currency("usd")
+    assert_equal "EUR", @parser.test_parse_currency("eur")
+    assert_equal "GBP", @parser.test_parse_currency("gbp")
+  end
+
+  test "parse_currency handles whitespace" do
+    assert_equal "USD", @parser.test_parse_currency("  usd  ")
+    assert_equal "EUR", @parser.test_parse_currency("\teur\n")
+  end
+
+  test "parse_currency returns nil for blank values" do
+    assert_nil @parser.test_parse_currency(nil)
+    assert_nil @parser.test_parse_currency("")
+    assert_nil @parser.test_parse_currency("   ")
+  end
+
+  test "parse_currency returns nil for invalid format" do
+    assert_nil @parser.test_parse_currency("US")      # Too short
+    assert_nil @parser.test_parse_currency("USDD")    # Too long
+    assert_nil @parser.test_parse_currency("123")     # Numbers
+    assert_nil @parser.test_parse_currency("US1")     # Mixed
+  end
+
+  test "parse_currency returns nil for XXX (no currency code)" do
+    # XXX is ISO 4217 for "no currency" but not valid for monetary operations
+    assert_nil @parser.test_parse_currency("XXX")
+    assert_nil @parser.test_parse_currency("xxx")
+  end
+
+  test "parse_currency returns nil for unknown 3-letter codes" do
+    # These are 3 letters but not recognized currencies
+    assert_nil @parser.test_parse_currency("ZZZ")
+    assert_nil @parser.test_parse_currency("ABC")
+  end
+
+  test "parse_currency accepts valid ISO currencies" do
+    # Common currencies
+    assert_equal "USD", @parser.test_parse_currency("USD")
+    assert_equal "EUR", @parser.test_parse_currency("EUR")
+    assert_equal "GBP", @parser.test_parse_currency("GBP")
+    assert_equal "JPY", @parser.test_parse_currency("JPY")
+    assert_equal "CHF", @parser.test_parse_currency("CHF")
+    assert_equal "CAD", @parser.test_parse_currency("CAD")
+    assert_equal "AUD", @parser.test_parse_currency("AUD")
+
+    # Less common but valid currencies
+    assert_equal "PLN", @parser.test_parse_currency("PLN")
+    assert_equal "SEK", @parser.test_parse_currency("SEK")
+    assert_equal "NOK", @parser.test_parse_currency("NOK")
+  end
+end