move all handlers from err2.go and add Handlers helper to handlers.go

Author: lainio

err2.go

@@ -3,7 +3,6 @@ package err2
 import (
 	"errors"
 	"fmt"
-	"os"
 
 	"github.com/lainio/err2/internal/handler"
 )
@@ -184,59 +183,6 @@ func Throwf(format string, args ...any) {
 	panic(err)
 }
 
-// Stderr is a built-in helper to use with Handle and Catch. It prints the
-// error to stderr and it resets the current error value. It's a handy Catch
-// handler in main function.
-//
-// You can use it like this:
-//
-//	func main() {
-//		defer err2.Catch(err2.Stderr)
-func Stderr(err error) error {
-	fmt.Fprintln(os.Stderr, err.Error())
-	return nil
-}
-
-// Stdout is a built-in helper to use with Handle and Catch. It prints the
-// error to stdout and it resets the current error value. It's a handy Catch
-// handler in main function.
-//
-// You can use it like this:
-//
-//	func main() {
-//		defer err2.Catch(err2.Stdout)
-func Stdout(err error) error {
-	fmt.Fprintln(os.Stdout, err.Error())
-	return nil
-}
-
-// Noop is a built-in helper to use with Handle and Catch. It keeps the current
-// error value the same. You can use it like this:
-//
-//	defer err2.Handle(&err, err2.Noop)
-func Noop(err error) error { return err }
-
-// Reset is a built-in helper to use with Handle and Catch. It sets the current
-// error value to nil. You can use it like this to reset the error:
-//
-//	defer err2.Handle(&err, err2.Reset)
-func Reset(error) error { return nil }
-
-// Err is a built-in helper to use with Handle and Catch. It offers simplifier
-// for error handling function for cases where you don't need to change the
-// current error value. For instance, if you want to just write error to stdout,
-// and don't want to use SetLogTracer and keep it to write to your logs.
-//
-//	defer err2.Catch(err2.Err(func(err error) {
-//		fmt.Println("ERROR:", err)
-//	}))
-func Err(f func(err error)) func(error) error {
-	return func(err error) error {
-		f(err)
-		return err
-	}
-}
-
 type nullDev struct{}
 
 func (nullDev) Write([]byte) (int, error) { return 0, nil }

handlers.go

@@ -0,0 +1,76 @@
+package err2
+
+import (
+	"fmt"
+	"os"
+)
+
+// Handlers is a helper to call several error handlers in a sequence.
+//
+//	defer err2.Handle(&err, err2.Handlers(err2.Log, MapToHTTPErr))
+func Handlers(f ...Handler) Handler {
+	return func(err error) error {
+		for _, handler := range f {
+			err = handler(err)
+		}
+		return err
+	}
+}
+
+// Stderr is a built-in helper to use with Handle and Catch. It prints the
+// error to stderr and it resets the current error value. It's a handy Catch
+// handler in main function.
+//
+// You can use it like this:
+//
+//	func main() {
+//		defer err2.Catch(err2.Stderr)
+func Stderr(err error) error {
+	fmt.Fprintln(os.Stderr, err.Error())
+	return nil
+}
+
+// Stdout is a built-in helper to use with Handle and Catch. It prints the
+// error to stdout and it resets the current error value. It's a handy Catch
+// handler in main function.
+//
+// You can use it like this:
+//
+//	func main() {
+//		defer err2.Catch(err2.Stdout)
+func Stdout(err error) error {
+	fmt.Fprintln(os.Stdout, err.Error())
+	return nil
+}
+
+// Noop is a built-in helper to use with Handle and Catch. It keeps the current
+// error value the same. You can use it like this:
+//
+//	defer err2.Handle(&err, err2.Noop)
+func Noop(err error) error { return err }
+
+// Reset is a built-in helper to use with Handle and Catch. It sets the current
+// error value to nil. You can use it like this to reset the error:
+//
+//	defer err2.Handle(&err, err2.Reset)
+func Reset(error) error { return nil }
+
+// Err is a built-in helper to use with Handle and Catch. It offers simplifier
+// for error handling function for cases where you don't need to change the
+// current error value. For instance, if you want to just write error to stdout,
+// and don't want to use SetLogTracer and keep it to write to your logs.
+//
+//	defer err2.Catch(err2.Err(func(err error) {
+//		fmt.Println("ERROR:", err)
+//	}))
+//
+// Note, that since Err helper we have other helpers like Stdout that allows
+// previous block be written as simple as:
+//
+//	defer err2.Catch(err2.Stdout)
+func Err(f func(err error)) Handler {
+	return func(err error) error {
+		f(err)
+		return err
+	}
+}

handlers_test.go

@@ -0,0 +1,45 @@
+package err2
+
+import (
+	"testing"
+
+	"github.com/lainio/err2/internal/test"
+)
+
+func TestHandlers(t *testing.T) {
+	t.Parallel()
+	type args struct {
+		f []Handler
+	}
+	tests := []struct {
+		name string
+		args args
+		want error
+	}{
+		{"one", args{f: []Handler{Noop}}, ErrNotFound},
+		{"two", args{f: []Handler{Noop, Noop}}, ErrNotFound},
+		{"three", args{f: []Handler{Noop, Noop, Noop}}, ErrNotFound},
+		{"reset", args{f: []Handler{Noop, Noop, Reset}}, nil},
+		{"reset first", args{f: []Handler{Reset, Noop, Noop}}, nil},
+		{"reset second", args{f: []Handler{Noop, Reset, Noop}}, nil},
+		{"set new first", args{f: []Handler{
+			func(error) error { return ErrAlreadyExist }, Noop}}, ErrAlreadyExist},
+		{"set new second", args{f: []Handler{Noop,
+			func(error) error { return ErrAlreadyExist }, Noop}}, ErrAlreadyExist},
+		{"set new first and reset", args{f: []Handler{
+			func(error) error { return ErrAlreadyExist }, Reset}}, nil},
+	}
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			errHandler := Handlers(tt.args.f...)
+			err := errHandler(ErrNotFound)
+			if err == nil {
+				test.Require(t, tt.want == nil)
+			} else {
+				test.RequireEqual(t, err.Error(), tt.want.Error())
+			}
+		})
+	}
+}