Add test case for `preventing_writes?`

Since the `preventing_writes?` is public API.

2 files changed, 11 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
index 1243236c09..346d4b067a 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
@@ -146,7 +146,7 @@ module ActiveRecord
         replica? || prevent_writes
       end
 
-      # Prevent writing to the database  regardless of role.
+      # Prevent writing to the database regardless of role.
       #
       # In some cases you may want to prevent writes to the database
       # even if you are on a database that can write. `while_preventing_writes`
diff --git a/activerecord/test/cases/adapter_test.rb b/activerecord/test/cases/adapter_test.rb
index 66e594d771..05d8aa59c4 100644
--- a/activerecord/test/cases/adapter_test.rb
+++ b/activerecord/test/cases/adapter_test.rb
@@ -163,6 +163,16 @@ module ActiveRecord
       end
     end
 
+    def test_preventing_writes_predicate
+      assert_not_predicate @connection, :preventing_writes?
+
+      @connection.while_preventing_writes do
+        assert_predicate @connection, :preventing_writes?
+      end
+
+      assert_not_predicate @connection, :preventing_writes?
+    end
+
     def test_errors_when_an_insert_query_is_called_while_preventing_writes
       assert_no_queries do
         assert_raises(ActiveRecord::ReadOnlyError) do