[IMP] validation error messages through optional use of jing

A long-standing issue with data files is that lxml (libxml2) has
trouble reporting useful errors, often going no further than "the file
is not valid" (libxml2 apparently has issues reporting useful errors
within non-trivial <choice>, which Odoo's data file schema makes
extensive use of) e.g. if a data file has some stray text in an
unexpected place (in this case, after a `</field>` tag in a
`<record>`), libxml2 will report:

ERROR:RELAXNGV:RELAXNG_ERR_EXTRACONTENT: Element odoo has extra content: data

Jing (the reference implementation) provides significantly better
error reporting:

error: text not allowed here; expected the element end-tag or element "field"

It's in java which is inconvenient and expensive for baseline
validation (and as a hard dependency), but there's now a "jingtrang"
package which bundles the relevant jars & invocation on
pypi (https://pypi.org/project/jingtrang/), making for a convenient
optional dependency for better development experience.

closes odoo/odoo#33666

Signed-off-by: Xavier Morel (xmo) <xmo@odoo.com>

odoo/tools/convert.py

@@ -5,6 +5,7 @@ import io
 import logging
 import os.path
 import re
+import subprocess
 import sys
 import time
 
@@ -13,6 +14,10 @@ from dateutil.relativedelta import relativedelta
 
 import pytz
 from lxml import etree, builder
+try:
+    import jingtrang
+except ImportError:
+    jingtrang = None
 
 import odoo
 from . import assertion_report, pycompat
@@ -771,13 +776,19 @@ def convert_csv_import(cr, module, fname, csvcontent, idref=None, mode='init',
 
 def convert_xml_import(cr, module, xmlfile, idref=None, mode='init', noupdate=False, report=None):
     doc = etree.parse(xmlfile)
-    relaxng = etree.RelaxNG(
-        etree.parse(os.path.join(config['root_path'],'import_xml.rng' )))
+    schema = os.path.join(config['root_path'], 'import_xml.rng')
+    relaxng = etree.RelaxNG(etree.parse(schema))
     try:
         relaxng.assert_(doc)
     except Exception:
-        _logger.info("The XML file '%s' does not fit the required schema !", xmlfile.name, exc_info=True)
-        _logger.info(ustr(relaxng.error_log.last_error))
+        _logger.exception("The XML file '%s' does not fit the required schema !", xmlfile.name)
+        if jingtrang:
+            p = subprocess.run(['pyjing', schema, xmlfile.name], stdout=subprocess.PIPE)
+            _logger.warn(p.stdout.decode())
+        else:
+            for e in relaxng.error_log:
+                _logger.warn(e)
+            _logger.info("Install 'jingtrang' for more precise and useful validation messages.")
         raise
 
     if isinstance(xmlfile, str):