add a function for the intial indexing run

Also moves postcodes to fully parallel indexing.

test/python/test_tools_refresh.py

@@ -0,0 +1,26 @@
+"""
+Test for various refresh functions.
+"""
+from pathlib import Path
+
+import pytest
+
+from nominatim.tools import refresh
+
+TEST_DIR = (Path(__file__) / '..' / '..').resolve()
+
+def test_refresh_import_wikipedia_not_existing(dsn):
+    assert 1 == refresh.import_wikipedia_articles(dsn, Path('.'))
+
+
+@pytest.mark.parametrize("replace", (True, False))
+def test_refresh_import_wikipedia(dsn, table_factory, temp_db_cursor, replace):
+    if replace:
+        table_factory('wikipedia_article')
+        table_factory('wikipedia_redirect')
+
+    # use the small wikipedia file for the API testdb
+    assert 0 == refresh.import_wikipedia_articles(dsn, TEST_DIR / 'testdb')
+
+    assert temp_db_cursor.scalar('SELECT count(*) FROM wikipedia_article') > 0
+    assert temp_db_cursor.scalar('SELECT count(*) FROM wikipedia_redirect') > 0