handle postcodes properly on word table updates

update_postcodes_from_db() needs to do the full postcode treatment
in order to derive the correct word table entries.

test/python/tokenizer/token_analysis/test_analysis_postcodes.py

@@ -0,0 +1,60 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# This file is part of Nominatim. (https://nominatim.org)
+#
+# Copyright (C) 2022 by the Nominatim developer community.
+# For a full list of authors see the git log.
+"""
+Tests for special postcode analysis and variant generation.
+"""
+import pytest
+
+from icu import Transliterator
+
+import nominatim.tokenizer.token_analysis.postcodes as module
+from nominatim.errors import UsageError
+
+DEFAULT_NORMALIZATION = """ :: NFD ();
+                            '🜳' > ' ';
+                            [[:Nonspacing Mark:] [:Cf:]] >;
+                            :: lower ();
+                            [[:Punctuation:][:Space:]]+ > ' ';
+                            :: NFC ();
+                        """
+
+DEFAULT_TRANSLITERATION = """ ::  Latin ();
+                              '🜵' > ' ';
+                          """
+
+@pytest.fixture
+def analyser():
+    rules = { 'analyzer': 'postcodes'}
+    config = module.configure(rules, DEFAULT_NORMALIZATION)
+
+    trans = Transliterator.createFromRules("test_trans", DEFAULT_TRANSLITERATION)
+    norm = Transliterator.createFromRules("test_norm", DEFAULT_NORMALIZATION)
+
+    return module.create(norm, trans, config)
+
+
+def get_normalized_variants(proc, name):
+    norm = Transliterator.createFromRules("test_norm", DEFAULT_NORMALIZATION)
+    return proc.get_variants_ascii(norm.transliterate(name).strip())
+
+
+@pytest.mark.parametrize('name,norm', [('12', '12'),
+                                       ('A 34 ', 'A 34'),
+                                       ('34-av', '34-AV')])
+def test_normalize(analyser, name, norm):
+    assert analyser.normalize(name) == norm
+
+
+@pytest.mark.parametrize('postcode,variants', [('12345', {'12345'}),
+                                               ('AB-998', {'ab 998', 'ab998'}),
+                                               ('23 FGH D3', {'23 fgh d3', '23fgh d3',
+                                                              '23 fghd3', '23fghd3'})])
+def test_get_variants_ascii(analyser, postcode, variants):
+    out = analyser.get_variants_ascii(postcode)
+
+    assert len(out) == len(set(out))
+    assert set(out) == variants