make sure redis command filters dates properly

also write the tests that i should have written a while ago for this

tests/app/commands/test_populate_redis.py

@@ -0,0 +1,69 @@
+from datetime import datetime
+
+from freezegun import freeze_time
+import pytest
+
+from app.commands import populate_redis_template_usage
+
+from tests.conftest import set_config
+from tests.app.db import create_notification, create_template, create_service
+
+
+def test_populate_redis_template_usage_does_nothing_if_redis_disabled(mocker, notify_api, sample_service):
+    mock_redis = mocker.patch('app.commands.redis_store')
+    with set_config(notify_api, 'REDIS_ENABLED', False):
+        with pytest.raises(AssertionError):
+            populate_redis_template_usage.callback.__wrapped__(sample_service.id, datetime.utcnow())
+
+    assert not mock_redis.called
+
+
+def test_populate_redis_template_usage_does_nothing_if_no_data(mocker, notify_api, sample_service):
+    mock_redis = mocker.patch('app.commands.redis_store')
+    with set_config(notify_api, 'REDIS_ENABLED', True):
+        populate_redis_template_usage.callback.__wrapped__(sample_service.id, datetime.utcnow())
+
+    assert not mock_redis.called
+
+
+@freeze_time('2017-06-12')
+def test_populate_redis_template_usage_only_populates_for_today(mocker, notify_api, sample_template):
+    mock_redis = mocker.patch('app.commands.redis_store')
+    # created at in utc
+    create_notification(sample_template, created_at=datetime(2017, 6, 9, 23, 0, 0))
+    create_notification(sample_template, created_at=datetime(2017, 6, 9, 23, 0, 0))
+    create_notification(sample_template, created_at=datetime(2017, 6, 10, 0, 0, 0))
+    create_notification(sample_template, created_at=datetime(2017, 6, 10, 23, 0, 0))  # actually on 11th BST
+
+    with set_config(notify_api, 'REDIS_ENABLED', True):
+        populate_redis_template_usage.callback.__wrapped__(sample_template.service_id, datetime(2017, 6, 10))
+
+    mock_redis.set_hash_and_expire.assert_called_once_with(
+        'service-{}-template-usage-2017-06-10'.format(sample_template.service_id),
+        {str(sample_template.id): 3},
+        notify_api.config['EXPIRE_CACHE_EIGHT_DAYS']
+    )
+
+
+@freeze_time('2017-06-12')
+def test_populate_redis_template_usage_only_populates_for_given_service(mocker, notify_api, notify_db_session):
+    mock_redis = mocker.patch('app.commands.redis_store')
+    # created at in utc
+    s1 = create_service(service_name='a')
+    s2 = create_service(service_name='b')
+    t1 = create_template(s1)
+    t2 = create_template(s2)
+
+    create_notification(t1, created_at=datetime(2017, 6, 10))
+    create_notification(t1, created_at=datetime(2017, 6, 10))
+
+    create_notification(t2, created_at=datetime(2017, 6, 10))
+
+    with set_config(notify_api, 'REDIS_ENABLED', True):
+        populate_redis_template_usage.callback.__wrapped__(s1.id, datetime(2017, 6, 10))
+
+    mock_redis.set_hash_and_expire.assert_called_once_with(
+        'service-{}-template-usage-2017-06-10'.format(s1.id),
+        {str(t1.id): 2},
+        notify_api.config['EXPIRE_CACHE_EIGHT_DAYS']
+    )