From 430e796980799feb75901b9918245b6b0bff3f54 Mon Sep 17 00:00:00 2001
From: Simon Charette <charette.s@gmail.com>
Date: Fri, 7 Feb 2020 10:37:25 +0100
Subject: [PATCH] Refs #31055 -- Made DiscoverRunner skip running system checks
 on unused test databases.

---
 django/test/runner.py            | 6 +++---
 docs/releases/3.1.txt            | 3 +++
 docs/topics/testing/advanced.txt | 8 ++++++--
 3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/django/test/runner.py b/django/test/runner.py
index ff124064db..5b634b2ac9 100644
--- a/django/test/runner.py
+++ b/django/test/runner.py
@@ -630,10 +630,10 @@ class DiscoverRunner:
             'buffer': self.buffer,
         }
 
-    def run_checks(self):
+    def run_checks(self, databases):
         # Checks are run after database creation since some checks require
         # database access.
-        call_command('check', verbosity=self.verbosity)
+        call_command('check', verbosity=self.verbosity, databases=databases)
 
     def run_suite(self, suite, **kwargs):
         kwargs = self.get_test_runner_kwargs()
@@ -695,7 +695,7 @@ class DiscoverRunner:
         old_config = self.setup_databases(aliases=databases)
         run_failed = False
         try:
-            self.run_checks()
+            self.run_checks(databases)
             result = self.run_suite(suite)
         except Exception:
             run_failed = True
diff --git a/docs/releases/3.1.txt b/docs/releases/3.1.txt
index fbce69d820..6bf57e0de3 100644
--- a/docs/releases/3.1.txt
+++ b/docs/releases/3.1.txt
@@ -332,6 +332,9 @@ Tests
 * Django test runner now supports a :option:`test --buffer` option to discard
   output for passing tests.
 
+* :class:`~django.test.runner.DiscoverRunner` now skips running the system
+  checks on databases not :ref:`referenced by tests<testing-multi-db>`.
+
 URLs
 ~~~~
 
diff --git a/docs/topics/testing/advanced.txt b/docs/topics/testing/advanced.txt
index 6ceaedc8fd..a909c5f3d8 100644
--- a/docs/topics/testing/advanced.txt
+++ b/docs/topics/testing/advanced.txt
@@ -637,9 +637,13 @@ Methods
     Creates the test databases by calling
     :func:`~django.test.utils.setup_databases`.
 
-.. method:: DiscoverRunner.run_checks()
+.. method:: DiscoverRunner.run_checks(databases)
 
-    Runs the :doc:`system checks </topics/checks>`.
+    Runs the :doc:`system checks </topics/checks>` on the test ``databases``.
+
+    .. versionadded:: 3.1
+
+        The ``databases`` parameter was added.
 
 .. method:: DiscoverRunner.run_suite(suite, **kwargs)