go test
refuses to build when a call to a function in the library to be tested by design contains a formatting directive. Is this intentional or is this a bug? Either way, is there a workaround?
Please note, unlike Call has possible formatting directive, this is not a call to a built-in function that doesn't accept formatting directives. It is a call to a function that I wrote and which is specifically designed to accept formatting directives.
Here is a contrived but complete reproduction. Note makeError
is designed to handle a format string. go build
works fine, but go test
produces the following error and does not run any tests:
.\example.go:16:13: makeError call has possible formatting directive %v
FAIL sandbox/example [build failed]
go version: go version go1.12.7 windows/amd64
example.go
:
package example
import "fmt"
type ErrExample struct {
data interface{}
msg string
}
func (e *ErrExample) Error() string {
return e.msg
}
func Divide(f1 float64, f2 float64) (float64, error) {
if f2 == 0.0 {
return 0, makeError(nil, "Cannot divide %v by 0", f1)
}
return f1 / f2, nil
}
func makeError(data interface{}, msgAndArgs ...interface{}) error {
msg := ""
switch len(msgAndArgs) {
case 0:
// Ignore
case 1:
msg = fmt.Sprint(msgAndArgs[0])
default:
if str, ok := msgAndArgs[0].(string); ok {
msg = fmt.Sprintf(str, msgAndArgs[1:]...)
}
msg = fmt.Sprint(msgAndArgs...)
}
return &ErrExample{data: data, msg: msg}
}
example_test.go
:
package example
import (
"testing"
)
func TestDivide(t *testing.T) {
_, err := Divide(1230, 0)
if err == nil {
t.Errorf("Expected error when dividing by 0")
}
}
From the help text of go test:
As part of building a test binary, go test runs go vet on the package and its test source files to identify significant problems. If go vet finds any problems, go test reports those and does not run the test binary. Only a high-confidence subset of the default go vet checks are used. That subset is: 'atomic', 'bool', 'buildtags', 'nilfunc', and 'printf'. You can see the documentation for these and other vet tests via "go doc cmd/vet". To disable the running of go vet, use the -vet=off flag."