[FIX] base_import: wrong date format

Current behaviour:
Wrong format used when importing dates

Steps to reproduce:
1. Change your language to German
2. Go to Sales > Orders
3. Export to XLSX
4. Change to dates to german format (ie: 10.09.2023)
5. Favorites > import records > Upload file
6. Click on Test
7. "does not match format '%Y-%m-%d'"

Cause of the issue:
Only default formats were taken into account
because options are empty.

opw-3540715

closes odoo/odoo#146744

X-original-commit: bdc006a81f83efddd693a8d4f4ffaec92da36f4a
Signed-off-by: Rémy Voet (ryv) <ryv@odoo.com>

addons/base_import/models/base_import.py

@@ -560,6 +560,9 @@ class Import(models.TransientModel):
                 val = self._remove_currency_symbol(val)
                 if val:
                     if options.get('float_thousand_separator') and options.get('float_decimal_separator'):
+                        if options['float_decimal_separator'] == '.' and val.count('.') > 1:
+                            # This is not a float so exit this try
+                            float('a')
                         val = val.replace(options['float_thousand_separator'], '').replace(options['float_decimal_separator'], '.')
                     # We are now sure that this is a float, but we still need to find the
                     # thousand and decimal separator
@@ -1528,7 +1531,7 @@ class Import(models.TransientModel):
 
         return input_file_data
 
-_SEPARATORS = [' ', '/', '-', '']
+_SEPARATORS = [' ', '/', '-', '.', '']
 _PATTERN_BASELINE = [
     ('%m', '%d', '%Y'),
     ('%d', '%m', '%Y'),

addons/test_base_import/tests/test_base_import.py

@@ -476,6 +476,35 @@ class test_convert_import_data(TransactionCase):
         # if results empty, no errors
         self.assertItemsEqual(results['messages'], [])
 
+    def test_date_fields_no_options(self):
+        import_wizard = self.env['base_import.import'].with_context(lang='de_DE').create({
+            'res_model': 'res.partner',
+            'file': 'name,date,create_date\n'
+                    '"foo","15.10.2023","15.10.2023 15:15:15"\n'.encode('utf-8'),
+            'file_type': 'text/csv',
+        })
+
+        opts = {
+            'date_format': '',
+            'datetime_format': '',
+            'quoting': '"',
+            'separator': ',',
+            'float_decimal_separator': '.',
+            'float_thousand_separator': ',',
+            'has_headers': True
+        }
+        result_parse = import_wizard.parse_preview({**opts})
+
+        opts = result_parse['options']
+        results = import_wizard.execute_import(
+            ['name', 'date', 'create_date'],
+            [],
+            {**opts}
+        )
+
+        # if results empty, no errors
+        self.assertItemsEqual(results['messages'], [])
+
     def test_parse_relational_fields(self):
         """ Ensure that relational fields float and date are correctly
         parsed during the import call.