Use pytest for the unit tests (#105)

* Use pytest for the unit tests

* Address PR comments

* Rework status check for some tests

* Add param ids for test_relations

* Simplify unit tests

* Fixes

* Use handle_exec in unit tests

* Remove left overs

* Fix

---------

Co-authored-by: arturo-seijas <[email protected]>

src/charm.py

@@ -8,7 +8,7 @@
 import typing
 from collections import defaultdict, namedtuple
 
-import ops.lib
+import ops
 from charms.data_platform_libs.v0.data_interfaces import (
     DatabaseCreatedEvent,
     DatabaseEndpointsChangedEvent,
@@ -27,7 +27,6 @@
 from database import DatabaseHandler
 
 logger = logging.getLogger(__name__)
-pgsql = ops.lib.use("pgsql", 1, "[email protected]")
 
 S3Info = namedtuple("S3Info", ["enabled", "region", "bucket", "endpoint"])
 

tests/unit/__init__.py

@@ -1,4 +1,2 @@
 # Copyright 2023 Canonical Ltd.
 # See LICENSE file for licensing details.
-
-"""Ops testing settings."""

tests/unit/helpers.py

@@ -0,0 +1,132 @@
+# Copyright 2023 Canonical Ltd.
+# See LICENSE file for licensing details.
+
+"""helpers for the unit test."""
+
+import contextlib
+import typing
+import unittest.mock
+
+from ops.model import Container
+from ops.testing import Harness
+
+from charm import DiscourseCharm
+
+DATABASE_NAME = "discourse"
+
+
+def start_harness(
+    *,
+    with_postgres: bool = True,
+    with_redis: bool = True,
+    with_ingress: bool = False,
+    with_config: typing.Optional[typing.Dict[str, typing.Any]] = None,
+):
+    """Start a harness discourse charm.
+
+    This is also a workaround for the fact that Harness
+    doesn't reinitialize the charm as expected.
+    Ref: https://github.com/canonical/operator/issues/736
+
+    Args:
+        - with_postgres: should a postgres relation be added
+        - with_redis: should a redis relation be added
+        - with_ingress: should a ingress relation be added
+        - with_config: apply some configuration to the charm
+
+    Returns: a ready to use harness instance
+    """
+    harness = Harness(DiscourseCharm)
+    harness.begin_with_initial_hooks()
+
+    # We catch all exec calls to the container by default
+    harness.handle_exec("discourse", [], result=0)
+
+    if with_postgres:
+        _add_postgres_relation(harness)
+
+    if with_redis:
+        _add_redis_relation(harness)
+        harness.framework.reemit()
+
+    if with_ingress:
+        _add_ingress_relation(harness)
+
+    if with_config is not None:
+        harness.update_config(with_config)
+        harness.container_pebble_ready("discourse")
+
+    return harness
+
+
+@contextlib.contextmanager
+def _patch_setup_completed():
+    """Patch filesystem calls in the _is_setup_completed and _set_setup_completed functions."""
+    setup_completed = False
+
+    def exists(*_args, **_kwargs):
+        return setup_completed
+
+    def push(*_args, **_kwargs):
+        nonlocal setup_completed
+        setup_completed = True
+
+    with unittest.mock.patch.multiple(Container, exists=exists, push=push):
+        yield
+
+
+def _add_postgres_relation(harness):
+    """Add postgresql relation and relation data to the charm.
+
+    Args:
+        - A harness instance
+
+    Returns: the same harness instance with an added relation
+    """
+
+    relation_data = {
+        "database": DATABASE_NAME,
+        "endpoints": "dbhost:5432,dbhost-2:5432",
+        "password": "somepasswd",  # nosec
+        "username": "someuser",
+    }
+
+    # get a relation ID for the test outside of __init__
+    harness.db_relation_id = (  # pylint: disable=attribute-defined-outside-init
+        harness.add_relation("database", "postgresql")
+    )
+    harness.add_relation_unit(harness.db_relation_id, "postgresql/0")
+    harness.update_relation_data(
+        harness.db_relation_id,
+        "postgresql",
+        relation_data,
+    )
+
+
+def _add_redis_relation(harness):
+    """Add redis relation and relation data to the charm.
+
+    Args:
+        - A harness instance
+
+    Returns: the same harness instance with an added relation
+    """
+    redis_relation_id = harness.add_relation("redis", "redis")
+    harness.add_relation_unit(redis_relation_id, "redis/0")
+    # We need to bypass protected access to inject the relation data
+    # pylint: disable=protected-access
+    harness.charm._stored.redis_relation = {
+        redis_relation_id: {"hostname": "redis-host", "port": 1010}
+    }
+
+
+def _add_ingress_relation(harness):
+    """Add ingress relation and relation data to the charm.
+
+    Args:
+        - A harness instance
+
+    Returns: the same harness instance with an added relation
+    """
+    nginx_route_relation_id = harness.add_relation("nginx-route", "ingress")
+    harness.add_relation_unit(nginx_route_relation_id, "ingress/0")