[+] convert types in Scan if possible

[ertaquo]

rowSets.Scan() checks if value type assignable to destination element type or destination type implements sql.Scanner interface. It doesn't check if value type can be converted to destination element type.

Using primitive type alias will result in error:

rs := NewRows([]string{"id", "active", "created", "status"}).        
        AddRow(1, true, NullTime{time.Now(), true}, NullInt{5, true}).        
        AddRow(2, false, NullTime{Valid: false}, NullInt{Valid: false})        
 
mock.ExpectQuery("SELECT (.+) FROM sales").WillReturnRows(rs)        
 
rows, err := mock.Query(context.Background(), "SELECT * FROM sales")        
if err != nil {        
        t.Fatalf("error '%s' was not expected while retrieving mock rows", err)        
}        
defer rows.Close()        
 
type boolAlias bool
 
// NullTime and NullInt are used from stubs_test.go        
var (        
        id      int        
        active  boolAlias        
        created NullTime        
        status  NullInt        
)        
 
if !rows.Next() {        
        t.Fatal("it must have had row in rows, but got empty result set instead")        
}        
 
err = rows.Scan(&id, &active, &created, &status)        
if err != nil {        
        t.Errorf("error '%s' was not expected while trying to scan row", err)        
}

pgxmock_test.go:514: error 'Destination kind 'bool' not supported for value kind 'bool' of column 'active'' was not expected while trying to scan row
pgxmock_test.go:522: expected 'active' to be 'true', but got 'false' instead
pgxmock_test.go:526: expected 'created' to be valid, but it {Time:0001-01-01 00:00:00 +0000 UTC Valid:false} is not
pgxmock_test.go:530: expected 'status' to be valid, but it {Integer:0 Valid:false} is not
pgxmock_test.go:534: expected 'status' to be '5', but got '0'
pgxmock_test.go:544: error 'Destination kind 'bool' not supported for value kind 'bool' of column 'active'' was not expected while trying to scan row

Of course, there won't be any problems if specify the type at AddRow() call, but it doesn't looks elegant:

type boolAlias bool

rs := NewRows([]string{"id", "active", "created", "status"}).        
        AddRow(1, boolAlias(true), NullTime{time.Now(), true}, NullInt{5, true}).        
        AddRow(2, boolAlias(false), NullTime{Valid: false}, NullInt{Valid: false})        

So I offer to use type conversion if possible.

The type conversion is being used within standard database/sql package, so I think it's compliant to use it in pgxmock library too:

	if dv.Kind() == sv.Kind() && sv.Type().ConvertibleTo(dv.Type()) {
		dv.Set(sv.Convert(dv.Type()))
		return nil
	}

[coveralls]

coverage: 93.975% (-0.2%) from 94.179%
when pulling a4e1308 on ertaquo:convert-on-scan
into ca59591 on pashagolub:master.

[pashagolub]

Thanks