[+] add test cases for BeginFunc() and BeginTx()

pgxmock_test.go

@@ -215,6 +215,38 @@ func TestTransactionExpectations(t *testing.T) {
 		t.Errorf("an error '%s' was not expected when committing a transaction", err)
 	}
 
+	// beginTx and commit
+	mock.ExpectBeginTx(pgx.TxOptions{})
+	mock.ExpectCommit()
+
+	tx, err = mock.BeginTx(context.Background(), pgx.TxOptions{})
+	if err != nil {
+		t.Errorf("an error '%s' was not expected when beginning a transaction", err)
+	}
+
+	err = tx.Commit(context.Background())
+	if err != nil {
+		t.Errorf("an error '%s' was not expected when committing a transaction", err)
+	}
+
+	// beginTxFunc and commit
+	mock.ExpectBeginTx(pgx.TxOptions{})
+	mock.ExpectCommit()
+
+	err = mock.BeginFunc(context.Background(), func(tx pgx.Tx) error { return nil })
+	if err != nil {
+		t.Errorf("an error '%s' was not expected when beginning a transaction", err)
+	}
+
+	// beginTxFunc and rollback
+	mock.ExpectBeginTx(pgx.TxOptions{})
+	mock.ExpectRollback()
+
+	err = mock.BeginFunc(context.Background(), func(tx pgx.Tx) error { return errors.New("smth wrong") })
+	if err == nil {
+		t.Error("an error was expected whithin a transaction, but got none")
+	}
+
 	// begin and rollback
 	mock.ExpectBegin()
 	mock.ExpectRollback()