1 files changed, 16 insertions, 2 deletions
diff --git a/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb b/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb
index 68bc87eaf8..830c0892d3 100644
--- a/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb
@@ -24,6 +24,18 @@ module ActiveRecord
         end
       end
 
+      def test_database_exists_returns_false_when_the_database_does_not_exist
+        config = { database: "non_extant_database", adapter: "postgresql" }
+        assert_not ActiveRecord::ConnectionAdapters::PostgreSQLAdapter.database_exists?(config),
+          "expected database #{config[:database]} to not exist"
+      end
+
+      def test_database_exists_returns_true_when_the_database_exists
+        config = ActiveRecord::Base.configurations["arunit"]
+        assert ActiveRecord::ConnectionAdapters::PostgreSQLAdapter.database_exists?(config),
+          "expected database #{config[:database]} to exist"
+      end
+
       def test_primary_key
         with_example_table do
           assert_equal "id", @connection.primary_key("ex")
@@ -241,9 +253,11 @@ module ActiveRecord
 
       def test_expression_index
         with_example_table do
-          @connection.add_index "ex", "mod(id, 10), abs(number)", name: "expression"
+          expr = "mod(id, 10), abs(number)"
+          @connection.add_index "ex", expr, name: "expression"
           index = @connection.indexes("ex").find { |idx| idx.name == "expression" }
-          assert_equal "mod(id, 10), abs(number)", index.columns
+          assert_equal expr, index.columns
+          assert_equal true, @connection.index_exists?("ex", expr, name: "expression")
         end
       end