Example
This example shows how to mock out a function call that is irrelevant to our unit test, and then use the defer statement to re-assign the mocked function call back to its original function.
var validate = validateDTD
// ParseXML parses b for XML elements and values, and returns them as a map of
// string key/value pairs.
func ParseXML(b []byte) (map[string]string, error) {
// we don't care about validating against DTD in our unit test
if err := validate(b); err != nil {
return err
}
// code to parse b etc.
}
func validateDTD(b []byte) error {
// get the DTD from some external storage, use it to validate b etc.
}
In our unit test,
func TestParseXML(t *testing.T) {
// assign the original validate function to a variable.
originalValidate = validate
// use the mockValidate function in this test.
validate = mockValidate
// defer the re-assignment back to the original validate function.
defer func() {
validate = originalValidate
}()
var input []byte
actual, err := ParseXML(input)
// assertion etc.
}
func mockValidate(b []byte) error {
return nil // always return nil since we don't care
}
