postgresql_ext: fix module's failing when available ext versions contain a pure string (#1099)

* postgresql_ext: fix module's failing when available ext versions contain a pure string

* Add unit tests

* Add changelog fragment

* fix

changelogs/fragments/1099-postgresql_ext_fix_failing_when_version_cannot_be_compared.yml

@@ -0,0 +1,2 @@
+bugfixes:
+- postgresql_ext - fix the module crashes when available ext versions cannot be compared with current version (https://github.com/ansible-collections/community.general/issues/1095).

plugins/modules/database/postgresql/postgresql_ext.py

@@ -106,6 +106,7 @@ notes:
   then PostgreSQL must also be installed on the remote host.
 - For Ubuntu-based systems, install the C(postgresql), C(libpq-dev),
   and C(python-psycopg2) packages on the remote host before using this module.
+- Incomparable versions, for example PostGIS ``unpackaged``, cannot be installed.
 requirements: [ psycopg2 ]
 author:
 - Daniel Schep (@dschep)
@@ -286,16 +287,40 @@ def ext_get_versions(cursor, ext):
     cursor.execute(query, {'ext': ext})
     res = cursor.fetchall()
 
-    available_versions = [
-        line['version']
-        for line in res
-        if LooseVersion(line['version']) > LooseVersion(current_version)
-    ]
+    available_versions = parse_ext_versions(current_version, res)
 
     if current_version == '0':
         current_version = False
 
-    return (current_version, sorted(available_versions, key=LooseVersion))
+    return (current_version, available_versions)
+
+
+def parse_ext_versions(current_version, ext_ver_list):
+    """Parse ext versions.
+
+    Args:
+      current_version (str) -- version to compare elements of ext_ver_list with
+      ext_ver_list (list) -- list containing dicts with versions
+
+    Return a sorted list with versions that are higher than current_version.
+
+    Note: Incomparable versions (e.g., postgis version "unpackaged") are skipped.
+    """
+    available_versions = []
+
+    for line in ext_ver_list:
+        if line['version'] == 'unpackaged':
+            continue
+
+        try:
+            if LooseVersion(line['version']) > LooseVersion(current_version):
+                available_versions.append(line['version'])
+        except Exception:
+            # When a version cannot be compared, skip it
+            # (there's a note in the documentation)
+            continue
+
+    return sorted(available_versions, key=LooseVersion)
 
 # ===========================================
 # Module execution.

tests/integration/targets/postgresql_ext/tasks/postgresql_ext_version_opt.yml

@@ -330,6 +330,23 @@
       - result.failed == true
       - result.msg == "Extension non_existent is not installed"
 
+  ######################################################################
+  # https://github.com/ansible-collections/community.general/issues/1095
+  - name: Install postgis
+    package:
+      name: postgis
+
+  - name: Create postgis extension
+    <<: *task_parameters
+    postgresql_ext:
+      <<: *pg_parameters
+      name: postgis
+      version: latest
+
+  - assert:
+      that:
+      - result is changed
+
   # Cleanup:
   - name: postgresql_ext_version - drop the extension
     <<: *task_parameters

tests/unit/plugins/modules/database/postgresql/test_postgresql_ext.py

@@ -0,0 +1,35 @@
+# Copyright 2020, Andrew Klychkov @Andersson007 <aaklychkov@mail.ru>
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+
+from __future__ import absolute_import, division, print_function
+__metaclass__ = type
+
+import pytest
+
+from ansible_collections.community.general.plugins.modules.database.postgresql.postgresql_ext import (
+    parse_ext_versions,
+)
+
+
+@pytest.mark.parametrize(
+    'current,test_input,expected',
+    [
+        (
+            '2.0.0',
+            [{'version': '3.1.0dev'}, {'version': '3.1.0devnext'}, {'version': 'unpackaged'}],
+            ['3.1.0dev', '3.1.0devnext'],
+        ),
+        (
+            '2.0.0',
+            [{'version': 'unpackaged'}, {'version': '3.1.0dev'}, {'version': '3.1.0devnext'}],
+            ['3.1.0dev', '3.1.0devnext'],
+        ),
+        (
+            '2.0.1',
+            [{'version': 'unpackaged'}, {'version': '2.0.0'}, {'version': '2.1.0dev'}],
+            ['2.1.0dev'],
+        ),
+    ]
+)
+def test_parse_ext_versions(current, test_input, expected):
+    assert parse_ext_versions(current, test_input) == expected