Add database_exists? method to connection adapters

When SQLite connects it will silently create a database if the database does not
exist. This behaviour causes different issues because of inconsistent behaviour
between adapters: #36383, #32914. This commit adds a `database_exists?` method
as a way to check the database without creating it. This is a stepping stone to
fully resolving the above issues.

1 files changed, 16 insertions, 0 deletions

diff --git a/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb b/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
index 508f7d8945..b6d72c7bcd 100644
--- a/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
+++ b/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
@@ -30,6 +30,17 @@ module ActiveRecord
         end
       end
 
+      def test_database_exists_returns_false_when_the_database_does_not_exist
+        assert_not SQLite3Adapter.database_exists?(adapter: "sqlite3", database: "non_extant_db"),
+          "expected non_extant_db to not exist"
+      end
+
+      def test_database_exists_returns_true_when_databae_exists
+        config = ActiveRecord::Base.configurations["arunit"]
+        assert SQLite3Adapter.database_exists?(config),
+          "expected #{config[:database]} to exist"
+      end
+
       unless in_memory_db?
         def test_connect_with_url
           original_connection = ActiveRecord::Base.remove_connection
@@ -53,6 +64,11 @@ module ActiveRecord
         end
       end
 
+      def test_database_exists_returns_true_for_an_in_memory_db
+        assert SQLite3Adapter.database_exists?(database: ":memory:"),
+          "Expected in memory database to exist"
+      end
+
       def test_column_types
         owner = Owner.create!(name: "hello".encode("ascii-8bit"))
         owner.reload