Merge pull request #390 from invopop/fix-mx-normalize

Fix panic when normalizing certain invoices in MX

CHANGELOG.md

@@ -15,6 +15,10 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/) and this p
 - `cbc.Code`: new `Join` and `JoinWith` methods to help concatenate codes.
 - `it-sdi-v1`: added CIG and CUP identity type codes.
 
+### Fixed
+
+- `mx`: fixed panic when normalizing an invoice with `tax` but no `ext` inside.
+
 ## [v0.201.0]
 
 ### Fixed

regimes/mx/invoice.go

@@ -17,7 +17,7 @@ func normalizeInvoice(inv *bill.Invoice) {
 	// set.
 	normalizeParty(inv.Supplier) // first do party
 	ext := make(tax.Extensions)
-	if inv.Tax != nil {
+	if inv.Tax != nil && inv.Tax.Ext != nil {
 		ext = inv.Tax.Ext
 	}
 	if ext.Has(extKeyIssuePlace) {

regimes/mx/invoice_test.go

@@ -21,6 +21,16 @@ func TestNormalizeInvoice(t *testing.T) {
 		require.NotNil(t, inv.Tax)
 		assert.Equal(t, tax.ExtValue("21000"), inv.Tax.Ext[cfdi.ExtKeyIssuePlace])
 	})
+
+	t.Run("no ext", func(t *testing.T) {
+		inv := baseInvoice()
+		inv.Tax = &bill.Tax{}
+		require.NoError(t, inv.Calculate())
+		require.NoError(t, inv.Validate())
+		require.NotNil(t, inv.Tax)
+		assert.Equal(t, tax.ExtValue("21000"), inv.Tax.Ext[cfdi.ExtKeyIssuePlace])
+	})
+
 	t.Run("with supplier address code", func(t *testing.T) {
 		inv := baseInvoice()
 		delete(inv.Supplier.Ext, cfdi.ExtKeyPostCode)