Move while_preventing_writes from conn to handler

If we put the `while_preventing_writes` on the connection then the
middleware that sends reads to the primary and ensures they can't write
will not work. The `while_preventing_writes` will only be applied to the
connection which it's called on - which in the case of the middleware is
Ar::Base.

This worked fine if you called it directly like
`OtherDbConn.connection.while_preventing_writes` but Rails didn't have a
way of knowing you wanted to call it on all the connections.

The change here moves the `while_preventing_writes` method from the
connection to the handler so that it can block writes to all queries for
that handler. This will apply to all the connections associated with
that handler.

1 files changed, 8 insertions, 6 deletions

diff --git a/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb b/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
index 22dc0eaad2..508f7d8945 100644
--- a/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
+++ b/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
@@ -19,6 +19,8 @@ module ActiveRecord
         @conn = Base.sqlite3_connection database: ":memory:",
                                         adapter: "sqlite3",
                                         timeout: 100
+
+        @connection_handler = ActiveRecord::Base.connection_handler
       end
 
       def test_bad_connection
@@ -572,7 +574,7 @@ module ActiveRecord
       def test_errors_when_an_insert_query_is_called_while_preventing_writes
         with_example_table "id int, data string" do
           assert_raises(ActiveRecord::ReadOnlyError) do
-            @conn.while_preventing_writes do
+            @connection_handler.while_preventing_writes do
               @conn.execute("INSERT INTO ex (data) VALUES ('138853948594')")
             end
           end
@@ -584,7 +586,7 @@ module ActiveRecord
           @conn.execute("INSERT INTO ex (data) VALUES ('138853948594')")
 
           assert_raises(ActiveRecord::ReadOnlyError) do
-            @conn.while_preventing_writes do
+            @connection_handler.while_preventing_writes do
               @conn.execute("UPDATE ex SET data = '9989' WHERE data = '138853948594'")
             end
           end
@@ -596,7 +598,7 @@ module ActiveRecord
           @conn.execute("INSERT INTO ex (data) VALUES ('138853948594')")
 
           assert_raises(ActiveRecord::ReadOnlyError) do
-            @conn.while_preventing_writes do
+            @connection_handler.while_preventing_writes do
               @conn.execute("DELETE FROM ex where data = '138853948594'")
             end
           end
@@ -608,7 +610,7 @@ module ActiveRecord
           @conn.execute("INSERT INTO ex (data) VALUES ('138853948594')")
 
           assert_raises(ActiveRecord::ReadOnlyError) do
-            @conn.while_preventing_writes do
+            @connection_handler.while_preventing_writes do
               @conn.execute("REPLACE INTO ex (data) VALUES ('249823948')")
             end
           end
@@ -619,7 +621,7 @@ module ActiveRecord
         with_example_table "id int, data string" do
           @conn.execute("INSERT INTO ex (data) VALUES ('138853948594')")
 
-          @conn.while_preventing_writes do
+          @connection_handler.while_preventing_writes do
             assert_equal 1, @conn.execute("SELECT data from ex WHERE data = '138853948594'").count
           end
         end
@@ -629,7 +631,7 @@ module ActiveRecord
         with_example_table "id int, data string" do
           @conn.execute("INSERT INTO ex (data) VALUES ('138853948594')")
 
-          @conn.while_preventing_writes do
+          @connection_handler.while_preventing_writes do
             assert_equal 1, @conn.execute("  SELECT data from ex WHERE data = '138853948594'").count
           end
         end