Added errors.Errorf() (#5)

errors.go

@@ -2,6 +2,7 @@ package errors
 
 import (
 	"errors"
+	"fmt"
 	"reflect"
 )
 
@@ -35,6 +36,18 @@ func Unwrap(err error) error {
 	return errors.Unwrap(err)
 }
 
+// Errorf formats according to a format specifier and returns the string as a
+// value that satisfies error.
+//
+// If the format specifier includes a %w verb with an error operand,
+// the returned error will implement an Unwrap method returning the operand. It is
+// invalid to include more than one %w verb or to supply it with an operand
+// that does not implement the error interface. The %w verb is otherwise
+// a synonym for %v.
+func Errorf(format string, a ...any) error {
+	return fmt.Errorf(format, a...)
+}
+
 // Last finds the last error in err's chain that matches target, and if one is found, sets
 // target to that error value and returns true. Otherwise, it returns false.
 //

errors_test.go

@@ -1,7 +1,6 @@
 package errors_test
 
 import (
-	"fmt"
 	"testing"
 
 	"github.com/mailgun/errors"
@@ -45,7 +44,7 @@ func TestLast(t *testing.T) {
 	err = errors.Wrap(err, "last")
 	err = errors.Wrap(err, "second")
 	err = errors.Wrap(err, "first")
-	err = fmt.Errorf("wrapped: %w", err)
+	err = errors.Errorf("wrapped: %w", err)
 
 	// errors.As() returns the "first" error in the chain with a stack trace
 	var first callstack.HasStackTrace