test: sanity tests for primary and replica

* new --replica option to `postgrest-with-postgresql-*`
* new command `postgrest-test-replica`
* new sanity tests on test_replica.py
* add postgrest-test-replica to postgrest-check and postgrest-coverage

test/io/config.py

@@ -45,6 +45,27 @@ def defaultenv(baseenv):
     }
 
 
+@pytest.fixture
+def replicaenv(defaultenv):
+    "Default environment for a PostgREST replica."
+    conf = {
+        "PGRST_DB_ANON_ROLE": "postgrest_test_anonymous",
+        "PGRST_DB_SCHEMAS": "replica",
+    }
+    return {
+        "primary": {
+            **defaultenv,
+            **conf,
+        },
+        "replica": {
+            **defaultenv,
+            **conf,
+            "PGHOST": os.environ["PGREPLICAHOST"],
+            "PGREPLICASLOT": os.environ["PGREPLICASLOT"],
+        },
+    }
+
+
 @pytest.fixture
 def slow_schema_cache_env(defaultenv):
     "Slow schema cache load environment PostgREST."