Unit testing Postgis version check

Refs #22334.

django/contrib/gis/tests/tests.py

+import unittest
+
+from django.contrib.gis.db.backends.postgis.operations import PostGISOperations
+from django.core.exceptions import ImproperlyConfigured
+from django.db import ProgrammingError
+
+
+class FakeConnection(object):
+    def __init__(self):
+        self.settings_dict = {
+            'NAME': 'test',
+        }
+
+
+class FakePostGISOperations(PostGISOperations):
+    def __init__(self, version=None):
+        self.version = version
+        self.connection = FakeConnection()
+
+    def _get_postgis_func(self, func):
+        if func == 'postgis_lib_version':
+            if self.version is None:
+                raise ProgrammingError
+            else:
+                return self.version
+        else:
+            raise NotImplementedError('This function was not expected to be called')
+
+
+class TestPostgisVersionCheck(unittest.TestCase):
+    """
+    Tests that the postgis version check parses correctly the version numbers
+    """
+
+    def test_get_version(self):
+        expect = '1.0.0'
+        ops = FakePostGISOperations(expect)
+        actual = ops.postgis_lib_version()
+        self.assertEqual(expect, actual)
+
+    def test_version_classic_tuple(self):
+        expect = ('1.2.3', 1, 2, 3)
+        ops = FakePostGISOperations(expect[0])
+        actual = ops.postgis_version_tuple()
+        self.assertEqual(expect, actual)
+
+    def test_version_dev_tuple(self):
+        expect = ('1.2.3dev', 1, 2, 3)
+        ops = FakePostGISOperations(expect[0])
+        actual = ops.postgis_version_tuple()
+        self.assertEqual(expect, actual)
+
+    def test_valid_version_numbers(self):
+        versions = [
+            ('1.3.0', 1, 3, 0),
+            ('2.1.1', 2, 1, 1),
+            ('2.2.0dev', 2, 2, 0),
+        ]
+
+        for version in versions:
+            ops = FakePostGISOperations(version[0])
+            actual = ops.spatial_version
+            self.assertEqual(version[1:], actual)
+
+    def test_invalid_version_numbers(self):
+        versions = ['nope', '123']
+
+        for version in versions:
+            ops = FakePostGISOperations(version)
+            self.assertRaises(Exception, lambda: ops.spatial_version)
+
+    def test_no_version_number(self):
+        ops = FakePostGISOperations()
+        self.assertRaises(ImproperlyConfigured, lambda: ops.spatial_version)