Do not fail invalid template variables with default filter

Author: jcushman

docs/usage.rst

@@ -33,7 +33,10 @@ You can switch it on in `pytest.ini`::
 
     [pytest]
     FAIL_INVALID_TEMPLATE_VARS = True
-    
+
+Invalid template variables will not fail the test if the variable uses the Django
+`default` filter, like `{{ does_not_exist:default:"ok" }}`.
+
 Additional pytest.ini settings
 ------------------------------
 

pytest_django/plugin.py

@@ -551,6 +551,15 @@ def __contains__(self, key):
         def _get_origin():
             stack = inspect.stack()
 
+            # Don't flag non-existent variables with default filter applied
+            from django.template.defaultfilters import default as default_filter
+            try:
+                has_default_filter = any(filter[0] is default_filter for filter in stack[2][0].f_locals["self"].filters)
+            except (AttributeError, IndexError, KeyError):
+                has_default_filter = False
+            if has_default_filter:
+                return True, None
+
             # Try to use topmost `self.origin` first (Django 1.9+, and with
             # TEMPLATE_DEBUG)..
             for f in stack[2:]:
@@ -562,7 +571,7 @@ def _get_origin():
                     except (AttributeError, KeyError):
                         continue
                     if origin is not None:
-                        return origin
+                        return False, origin
 
             from django.template import Template
 
@@ -579,10 +588,14 @@ def _get_origin():
             # ``django.template.base.Template``
             template = f_locals["self"]
             if isinstance(template, Template):
-                return template.name
+                return False, template.name
+
+            return False, None
 
         def __mod__(self, var):
-            origin = self._get_origin()
+            has_default_filter, origin = self._get_origin()
+            if has_default_filter:
+                return ""
             if origin:
                 msg = "Undefined template variable '{}' in '{}'".format(var, origin)
             else:

tests/test_environment.py

@@ -112,11 +112,44 @@ def test_ignore(client):
     ROOT_URLCONF = 'tpkg.app.urls'
     """
 )
-def test_invalid_template_with_default_if_none(django_testdir):
+def test_invalid_template_with_default(django_testdir):
     django_testdir.create_app_file(
         """
             <div>{{ data.empty|default:'d' }}</div>
             <div>{{ data.none|default:'d' }}</div>
+            <div>{{ data.missing|default:'d' }}</div>
+        """,
+        "templates/the_template.html",
+    )
+    django_testdir.create_test_module(
+        """
+        def test_for_invalid_template():
+            from django.shortcuts import render
+
+
+            render(
+                request=None,
+                template_name='the_template.html',
+                context={'data': {'empty': '', 'none': None}},
+            )
+        """
+    )
+    result = django_testdir.runpytest_subprocess("--fail-on-template-vars")
+    result.stdout.fnmatch_lines_random(["tpkg/test_the_test.py ."])
+
+
+@pytest.mark.django_project(
+    extra_settings="""
+    TEMPLATE_LOADERS = (
+        'django.template.loaders.filesystem.Loader',
+        'django.template.loaders.app_directories.Loader',
+    )
+    ROOT_URLCONF = 'tpkg.app.urls'
+    """
+)
+def test_invalid_template_with_default_if_none(django_testdir):
+    django_testdir.create_app_file(
+        """
             <div>{{ data.empty|default_if_none:'d' }}</div>
             <div>{{ data.none|default_if_none:'d' }}</div>
             <div>{{ data.missing|default_if_none:'d' }}</div>