func Errorf(t TestingT, err error, msg string, args ...interface{}) bool {
	if h, ok := t.(tHelper); ok {
		h.Helper()
	}
	return Error(t, err, append([]interface{}{msg}, args...)...)
}
Errorf asserts that a function returned an error (i.e. not `nil`).

actualObj, err := SomeFunction()
if assert.Errorf(t, err, "error message %s", "formatted") {
assert.Equal(t, expectedErrorf, err)
}
package assert
import (
	http "net/http"
	url "net/url"
	time "time"
)
func Conditionf(t TestingT, comp Comparison, msg string, args ...interface{}) bool {
	if h, ok := t.(tHelper); ok {
		h.Helper()
	}
	return Condition(t, comp, append([]interface{}{msg}, args...)...)
}
func Containsf(t TestingT, s interface{}, contains interface{}, msg string, args ...interface{}) bool {
	if h, ok := t.(tHelper); ok {
		h.Helper()
	}
	return Contains(t, s, contains, append([]interface{}{msg}, args...)...)
}
func DirExistsf(t TestingT, path string, msg string, args ...interface{}) bool {
	if h, ok := t.(tHelper); ok {
		h.Helper()
	}
	return DirExists(t, path, append([]interface{}{msg}, args...)...)
}
func ElementsMatchf(t TestingT, listA interface{}, listB interface{}, msg string, args ...interface{}) bool {
	if h, ok := t.(tHelper); ok {
		h.Helper()
	}
	return ElementsMatch(t, listA, listB, append([]interface{}{msg}, args...)...)
}
func Emptyf(t TestingT, object interface{}, msg string, args ...interface{}) bool {
	if h, ok := t.(tHelper); ok {
		h.Helper()
	}
	return Empty(t, object, append([]interface{}{msg}, args...)...)
}
func Equalf(t TestingT, expected interface{}, actual interface{}, msg string, args ...interface{}) bool {
	if h, ok := t.(tHelper); ok {
		h.Helper()
	}
	return Equal(t, expected, actual, append([]interface{}{msg}, args...)...)
}
func EqualErrorf(t TestingT, theError error, errString string, msg string, args ...interface{}) bool {
	if h, ok := t.(tHelper); ok {
		h.Helper()
	}
	return EqualError(t, theError, errString, append([]interface{}{msg}, args...)...)
}
func EqualValuesf(t TestingT, expected interface{}, actual interface{}, msg string, args ...interface{}) bool {
	if h, ok := t.(tHelper); ok {
		h.Helper()
	}
	return EqualValues(t, expected, actual, append([]interface{}{msg}, args...)...)
}