Pgxmock batch example in Go

examples/batch/batch.go

@@ -0,0 +1,167 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"os"
+
+	pgx "github.com/jackc/pgx/v5"
+	pgconn "github.com/jackc/pgx/v5/pgconn"
+	pgxpool "github.com/jackc/pgx/v5/pgxpool"
+)
+
+type PgxIface interface {
+	Begin(context.Context) (pgx.Tx, error)
+	Exec(context.Context, string, ...interface{}) (pgconn.CommandTag, error)
+	Close()
+}
+
+func databaseSetup(db PgxIface) (err error) {
+	// Create a new table 'ledger'
+	sql := `CREATE TABLE IF NOT EXISTS ledger (
+		id BIGINT PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY,
+		description TEXT NOT NULL,
+		amount BIGINT NOT NULL);`
+	_, err = db.Exec(context.Background(), sql)
+	return err
+}
+
+func iterateResults(br pgx.BatchResults, QueuedQueries []*pgx.QueuedQuery) error {
+
+	file, err := os.Create("OUTPUT.md")
+	if err != nil {
+		return fmt.Errorf("iterateResults: %s", err)
+	}
+	defer file.Close()
+
+	fmt.Fprintf(file, "## PostgreSQL Batch Example output\n")
+
+	// Iterate over a batch of queued queries
+	for _, query := range QueuedQueries {
+
+		// Print SQL field of the current query
+		fmt.Fprintf(file, "### %v \n", query.SQL)
+
+		//  reads results from the current query
+		rows, err := br.Query()
+		if err != nil {
+			return fmt.Errorf("iterateResults: %s", err)
+		}
+
+		// Print column headers
+		fmt.Fprintf(file, "- *DESCRIPTION* , *AMOUNT* \n")
+		// Iterate over the resulted rows
+		//
+		var id, amount, descr = int64(0), int64(0), string("")
+		_, err = pgx.ForEachRow(rows, []any{&id, &descr, &amount}, func() error {
+			fmt.Fprintf(file, "- \"%v\" , %d \n", descr, amount)
+			return nil
+		})
+		if err != nil {
+			return fmt.Errorf("iterateResults: %s", err)
+		}
+	}
+
+	return err
+}
+
+func requestBatch(db PgxIface) (err error) {
+
+	// Initialize a database object
+	tx, err := db.Begin(context.Background())
+	if err != nil {
+		return fmt.Errorf("requestBatch: %s", err)
+	}
+	// Finally, commit changes or rollback
+	defer func() {
+		switch err {
+		case nil:
+			err = tx.Commit(context.Background())
+		default:
+			_ = tx.Rollback(context.Background())
+		}
+	}()
+
+	// Create a Batch object
+	batch := &pgx.Batch{}
+
+	// Add SQL commands to queue
+	batch.Queue(
+		`INSERT INTO ledger(description, amount) VALUES ($1, $2), ($3, $4)`,
+		"first item", 1, "second item", 2)
+
+	batch.Queue("SELECT * FROM ledger")
+	batch.Queue("SELECT * FROM ledger WHERE amount = 1")
+
+	// Efficiently transmits queued queries as a single transaction.
+	// After the queries are run, a BatchResults object is returned.
+	//
+	br := tx.SendBatch(context.Background(), batch)
+	if br == nil {
+		return errors.New("SendBatch returns a NIL object")
+	}
+	defer br.Close()
+
+	// Read the first query
+	_, err = br.Exec()
+	if err != nil {
+		return err
+	}
+	// Iterate over batch results and queries.
+	// Note: the first query is left out of the queue.
+	//
+	return iterateResults(br, batch.QueuedQueries[1:])
+
+}
+
+func databaseCleanup(db PgxIface) (err error) {
+
+	// Initialize a database object
+	tx, err := db.Begin(context.Background())
+	if err != nil {
+		return fmt.Errorf("databaseCleanup: %s", err)
+	}
+	// Finally, commit changes or rollback
+	defer func() {
+		switch err {
+		case nil:
+			err = tx.Commit(context.Background())
+		default:
+			_ = tx.Rollback(context.Background())
+		}
+	}()
+
+	// Delete all rows in table ledger
+	sql := `DELETE FROM ledger ;`
+
+	// Execute SQL commands
+	_, err = tx.Exec(context.Background(), sql)
+
+	return err
+}
+
+func main() {
+
+	// @NOTE: the real connection is not required for tests
+	db, err := pgxpool.New(context.Background(), "postgres://<user>:<password>@<hostname>/<database>")
+	if err != nil {
+		panic(err)
+	}
+	defer db.Close()
+
+	// Create a database table
+	if err = databaseSetup(db); err != nil {
+		panic(err)
+	}
+
+	// Create and send a batch request
+	if err = requestBatch(db); err != nil {
+		panic(err)
+	}
+
+	// Delete all rows in table ledger
+	if err = databaseCleanup(db); err != nil {
+		panic(err)
+	}
+}

examples/batch/batch_test.go

@@ -0,0 +1,41 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/pashagolub/pgxmock/v4"
+)
+
+// a successful test case
+func TestShouldSelectRows(t *testing.T) {
+	mock, err := pgxmock.NewPool()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer mock.Close()
+
+	// TODO
+}
+
+// a failing test case
+func TestShouldRollbackOnFailure(t *testing.T) {
+	mock, err := pgxmock.NewPool()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer mock.Close()
+
+	mock.ExpectBegin()
+	// TODO: mock.ExpectBatch()
+	mock.ExpectRollback()
+
+	// now we execute our method
+	if err = requestBatch(mock); 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)
+	}
+}