package main

import (
	"context"

	pgx "github.com/jackc/pgx/v5"
)

type PgxIface interface {
	Begin(context.Context) (pgx.Tx, error)
	Close(context.Context) error
}

func recordStats(db PgxIface, userID, productID int) (err error) {
	if tx, err := db.Begin(context.Background()); err != nil {
		return
	}
	defer func() {
		switch err {
		case nil:
			err = tx.Commit(context.Background())
		default:
			_ = tx.Rollback(context.Background())
		}
	}()
	sql := "UPDATE products SET views = views + 1"
	if _, err = tx.Exec(context.Background(), sql); err != nil {
		return
	}
	sql = "INSERT INTO product_viewers (user_id, product_id) VALUES ($1, $2)"
	if _, err = tx.Exec(context.Background(), sql, userID, productID); err != nil {
		return
	}
	return
}

func main() {
	// @NOTE: the real connection is not required for tests
	db, err := pgx.Connect(context.Background(), "postgres:https://rolname@hostname/dbname")
	if err != nil {
		panic(err)
	}
	defer db.Close(context.Background())

	if err = recordStats(db, 1 /*some user id*/, 5 /*some product id*/); err != nil {
		panic(err)
	}
}

package main

import (
	"context"
	"fmt"
	"testing"

	"github.com/pashagolub/pgxmock/v4"
)

// a successful case
func TestShouldUpdateStats(t *testing.T) {
	mock, err := pgxmock.NewPool()
	if err != nil {
		t.Fatal(err)
	}
	defer mock.Close()

	mock.ExpectBegin()
	mock.ExpectExec("UPDATE products").
		WillReturnResult(pgxmock.NewResult("UPDATE", 1))
	mock.ExpectExec("INSERT INTO product_viewers").
		WithArgs(2, 3).
		WillReturnResult(pgxmock.NewResult("INSERT", 1))
	mock.ExpectCommit()

	// now we execute our method
	if err = recordStats(mock, 2, 3); err != nil {
		t.Errorf("error was not expected while updating: %s", err)
	}

	// we make sure that all expectations were met
	if err := mock.ExpectationsWereMet(); err != nil {
		t.Errorf("there were unfulfilled expectations: %s", err)
	}
}

// a failing test case
func TestShouldRollbackStatUpdatesOnFailure(t *testing.T) {
	mock, err := pgxmock.NewPool()
	if err != nil {
		t.Fatal(err)
	}
	defer mock.Close()

	mock.ExpectBegin()
	mock.ExpectExec("UPDATE products").
		WillReturnResult(pgxmock.NewResult("UPDATE", 1))
	mock.ExpectExec("INSERT INTO product_viewers").
		WithArgs(2, 3).
		WillReturnError(fmt.Errorf("some error"))
	mock.ExpectRollback()

	// now we execute our method
	if err = recordStats(mock, 2, 3); err == nil {
		t.Errorf("was expecting an error, but there was none")
	}

	// we make sure that all expectations were met
	if err := mock.ExpectationsWereMet(); err != nil {
		t.Errorf("there were unfulfilled expectations: %s", err)
	}
}

	mock, err := pgxmock.New(context.Background(), pgxmock.QueryMatcherOption(pgxmock.QueryMatcherEqual))

type AnyTime struct{}

// Match satisfies sqlmock.Argument interface
func (a AnyTime) Match(v interface{}) bool {
	_, ok := v.(time.Time)
	return ok
}

func TestAnyTimeArgument(t *testing.T) {
	t.Parallel()
	db, mock, err := New()
	if err != nil {
		t.Errorf("an error '%s' was not expected when opening a stub database connection", err)
	}
	defer db.Close()

	mock.ExpectExec("INSERT INTO users").
		WithArgs("john", AnyTime{}).
		WillReturnResult(NewResult(1, 1))

	_, err = db.Exec("INSERT INTO users(name, created_at) VALUES (?, ?)", "john", time.Now())
	if err != nil {
		t.Errorf("error '%s' was not expected, while inserting a row", err)
	}

	if err := mock.ExpectationsWereMet(); err != nil {
		t.Errorf("there were unfulfilled expectations: %s", err)
	}
}