Add test for postgresql specific JSONField

tests/models.py

@@ -1,8 +1,12 @@
+import django
+
 from django.db import models
 from django.db.models.signals import pre_save
 from django.utils import timezone
+
 from dirtyfields import DirtyFieldsMixin
 from dirtyfields.compare import timezone_support_compare
+from tests.utils import is_postgresql_env_with_json_field
 
 
 class TestModel(DirtyFieldsMixin, models.Model):
@@ -101,3 +105,10 @@ def pre_save(instance, *args, **kwargs):
 class TestModelWithoutM2MCheck(DirtyFieldsMixin, models.Model):
     characters = models.CharField(blank=True, max_length=80)
     ENABLE_M2M_CHECK = False
+
+
+if is_postgresql_env_with_json_field():
+    from django.contrib.postgres.fields import JSONField
+
+    class TestModelWithJSONField(DirtyFieldsMixin, models.Model):
+        json_field = JSONField()

tests/test_postgresql_specific.py

@@ -0,0 +1,16 @@
+import pytest
+
+from tests.utils import is_postgresql_env_with_json_field
+
+
+@pytest.mark.skipif(not is_postgresql_env_with_json_field(),
+                    reason="requires postgresql and Django 1.9+")
+@pytest.mark.django_db
+def test_dirty_json_field():
+    from tests.models import TestModelWithJSONField
+
+    tm = TestModelWithJSONField.objects.create(json_field={'data': 'dummy_data'})
+    assert tm.get_dirty_fields() == {}
+
+    tm.json_field = {'data': 'foo'}
+    assert tm.get_dirty_fields() == {'json_field': {'data': 'dummy_data'}}

tests/utils.py

@@ -1,5 +1,7 @@
 import re
 
+import django
+
 from django.conf import settings
 from django.db import connection
 
@@ -55,3 +57,12 @@ def __init__(self, model_class, number):
         regex = r'^.*SELECT.*FROM "tests_%s".*$' % model_name
 
         super(assert_select_number_queries_on_model, self).__init__(regex, number)
+
+
+def is_postgresql_env_with_json_field():
+    try:
+        PG_VERSION = connection.pg_version
+    except AttributeError:
+        PG_VERSION = 0
+
+    return PG_VERSION >= 90400 and django.VERSION >= (1, 9)