Simplify scanning compute logs in tests (#7997)

Implement LogUtils in the Endpoint fixture class, so that the
"log_contains" function can be used on compute logs too.

Per discussion at:
#7288 (comment)

test_runner/fixtures/neon_fixtures.py

@@ -3386,7 +3386,7 @@ def static_proxy(
         yield proxy
 
 
-class Endpoint(PgProtocol):
+class Endpoint(PgProtocol, LogUtils):
     """An object representing a Postgres compute endpoint managed by the control plane."""
 
     def __init__(
@@ -3452,6 +3452,7 @@ def create(
         )
         path = Path("endpoints") / self.endpoint_id / "pgdata"
         self.pgdata_dir = os.path.join(self.env.repo_dir, path)
+        self.logfile = self.endpoint_path() / "compute.log"
 
         config_lines = config_lines or []
 

test_runner/regress/test_hot_standby.py

@@ -1,6 +1,5 @@
 import asyncio
 import os
-import re
 import threading
 import time
 from functools import partial
@@ -18,20 +17,6 @@
 from fixtures.utils import wait_until
 
 
-# Check for corrupted WAL messages which might otherwise go unnoticed if
-# reconnection fixes this.
-def scan_standby_log_for_errors(secondary):
-    log_path = secondary.endpoint_path() / "compute.log"
-    with log_path.open("r") as f:
-        markers = re.compile(
-            r"incorrect resource manager data|record with incorrect|invalid magic number|unexpected pageaddr"
-        )
-        for line in f:
-            if markers.search(line):
-                log.info(f"bad error in standby log: {line}")
-                raise AssertionError()
-
-
 def test_hot_standby(neon_simple_env: NeonEnv):
     env = neon_simple_env
 
@@ -91,7 +76,11 @@ def test_hot_standby(neon_simple_env: NeonEnv):
                         assert response is not None
                         assert response == responses[query]
 
-            scan_standby_log_for_errors(secondary)
+            # Check for corrupted WAL messages which might otherwise go unnoticed if
+            # reconnection fixes this.
+            assert not secondary.log_contains(
+                "incorrect resource manager data|record with incorrect|invalid magic number|unexpected pageaddr"
+            )
 
     # clean up
     if slow_down_send:

test_runner/regress/test_migrations.py

@@ -8,8 +8,6 @@ def test_migrations(neon_simple_env: NeonEnv):
     env.neon_cli.create_branch("test_migrations", "empty")
 
     endpoint = env.endpoints.create("test_migrations")
-    log_path = endpoint.endpoint_path() / "compute.log"
-
     endpoint.respec(skip_pg_catalog_updates=False)
     endpoint.start()
 
@@ -22,9 +20,7 @@ def test_migrations(neon_simple_env: NeonEnv):
         migration_id = cur.fetchall()
         assert migration_id[0][0] == num_migrations
 
-    with open(log_path, "r") as log_file:
-        logs = log_file.read()
-        assert f"INFO handle_migrations: Ran {num_migrations} migrations" in logs
+    endpoint.assert_log_contains(f"INFO handle_migrations: Ran {num_migrations} migrations")
 
     endpoint.stop()
     endpoint.start()
@@ -36,6 +32,4 @@ def test_migrations(neon_simple_env: NeonEnv):
         migration_id = cur.fetchall()
         assert migration_id[0][0] == num_migrations
 
-    with open(log_path, "r") as log_file:
-        logs = log_file.read()
-        assert "INFO handle_migrations: Ran 0 migrations" in logs
+    endpoint.assert_log_contains("INFO handle_migrations: Ran 0 migrations")