Npgsql.Tests.ReaderNewSchemaTests.IsKey C# (CSharp) Method

        public void IsKey()
        {
            using (var conn = OpenConnection())
            {
                conn.ExecuteNonQuery("CREATE TEMP TABLE data (id INT PRIMARY KEY, non_id INT, uniq INT UNIQUE)");

                using (var cmd = new NpgsqlCommand("SELECT id,non_id,uniq,8 FROM data", conn))
                using (var reader = cmd.ExecuteReader(CommandBehavior.SchemaOnly | CommandBehavior.KeyInfo))
                {
                    var columns = reader.GetColumnSchema();
                    Assert.That(columns[0].IsKey, Is.True);
                    Assert.That(columns[1].IsKey, Is.False);

                    // Note: according to the old API docs any unique column is considered key.
                    // https://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqldatareader.getschematable(v=vs.110).aspx
                    // But in the new API we have a separate IsUnique so IsKey should be false
                    Assert.That(columns[2].IsKey, Is.False);

                    Assert.That(columns[3].IsKey, Is.Null);
                }
            }
        }