Error "query was not expected" on INSERT while unit testing using sqlmock

Question

I'm trying to run an unit test that executes an INSERT into DB, so I mocked exactly the same query string that the gorm log displays with the same arguments but I'm still having problem while trying to execute the test, (with postgres driver) because it seems like the sql-mock does not match the SQL that I defined in the mock and display an error like:

"**call to Query** 'INSERT  INTO "customer" ("customer_key","first_name","middle_name","last_surname") VALUES ($1,$2,$3,$4) RETURNING "customer"."customer_key"' with args 
[{Name: Ordinal:1 Value:RLKuxK-wnj8SUn50iFMjsrCtikTLTEmUFP7fOSE2veI=}
 {Name: Ordinal:2 Value:Martín} {Name: Ordinal:3 Value:Constan} 
{Name: Ordinal:4 Value:Smith}] 
**was not expected** "

GO Playgound Running example

repository.go

...
func (r *repository) Register(customer *models.Customer) (*string, error) {
    err := r.db.Create(&customer).Error
    if err != nil {
        return nil, err
    }

    return customer.CustomerKey, nil
}
...

repository_test.go

func TestRegister(t *testing.T) {
    qStr := `INSERT  INTO "customer" ("customer_key","first_name","middle_name","last_surname") 
    VALUES ($1,$2,$3,$4) RETURNING "customer"."customer_key"`

    t.Run("Must return the newly created customer key, if given customer input is valid", func(t *testing.T) {
        r := mocks.CustomerModel

        mock.MatchExpectationsInOrder(false)
        mock.ExpectBegin()
        mock.ExpectQuery(regexp.QuoteMeta(qStr)).
            WithArgs(r.CustomerKey, r.FirstName, r.MiddleName, r.LastSurname).
            WillReturnRows(sqlmock.NewRows([]string{"customer_key"}).AddRow(r.CustomerKey))
        mock.ExpectCommit()
        customerKey, err := repo.Register(r)

        assert.Nil(t, err)
        assert.NotNil(t, customerKey)
    })
}

and I get the following error:

Running tool: /usr/local/go/bin/go test -timeout 30s /internal/customer -run ^(TestRegister)$
call to Query 'INSERT  INTO "customer" ("customer_key","first_name","middle_name","last_surname") VALUES ($1,$2,$3,$4) RETURNING "customer"."customer_key"' with args [{Name: Ordinal:1 Value:RLKuxK-wnj8SUn50iFMjsrCtikTLTEmUFP7fOSE2veI=}
 {Name: Ordinal:2 Value:Martín} {Name: Ordinal:3 Value:Constan} 
{Name: Ordinal:4 Value:Smith}] 
was not expected <----------------------ERROR-------------------------

INSERT  INTO "customer" ("customer_key","first_name","middle_name","last_surname") VALUES ('RLKuxK-wnj8SUn50iFMjsrCtikTLTEmUFP7fOSE2veI=','Martín','','Constan','Smith'') RETURNING "customer"."customer_key"  
[0 rows affected or returned ]

[35m(data-repository/internal/customer/repository.go:57)[0m 
[33m[2020-01-22 19:39:18][0m [31;1m call to Query 'INSERT INTO "customer" ("customer_key","first_name","middle_name","last_surname") VALUES ($1,$2,$3,$4) RETURNING "customer"."customer_key"' with args [{Name: Ordinal:1 Value:RLKuxK-wnj8SUn50iFMjsrCtikTLTEmUFP7fOSE2veI=} {Name: Ordinal:2 Value:Martín} {Name: Ordinal:3 Value:Constan} {Name: Ordinal:4 Value:Smith}] 
was not expected <----------------------ERROR AGAIN-------------------------

--- FAIL: TestRegister (0.00s)
    --- FAIL: TestRegister/Must_return_the_newly_created_customer_key,_if_given_customer_input_is_valid (0.00s)
        data-repository/internal/customer/repository_test.go:89: 
                Error Trace:    repository_test.go:89
                Error:          Expected nil, but got: &status.statusError{Code:13, Message:"An error occurred.", Details:[]*any.Any{(*any.Any)(0xc000215f90)}, XXX_NoUnkeyedLiteral:struct {}{}, XXX_unrecognized:[]uint8(nil), XXX_sizecache:0}
                Test:           TestRegister/Must_return_the_newly_created_customer_key,_if_given_customer_input_is_valid
FAIL
FAIL    /internal/customer  0.008s
FAIL
Error: Tests failed.

I'm using the following versions:

github.com/DATA-DOG/go-sqlmock v1.4.0 and github.com/jinzhu/gorm v1.9.11

I would appreciate any help...