Handler multi call moved to internal/handler pkg with tests

Author: lainio

handlers.go

@@ -3,7 +3,6 @@ package err2
 import (
 	"fmt"
 	"os"
-)
 
 	"github.com/lainio/err2/internal/handler"
 )
@@ -65,3 +64,11 @@ func Err(f func(err error)) Handler {
 		return err
 	}
 }
+
+const lvl = 10
+
+// Log prints error string to the current log that is set by SetLogTracer.
+func Log(err error) error {
+	_ = handler.LogOutput(lvl, err.Error())
+	return err
+}

handlers_test.go

@@ -0,0 +1,53 @@
+package handler_test
+
+import (
+	"testing"
+
+	"github.com/lainio/err2"
+	"github.com/lainio/err2/internal/handler"
+	"github.com/lainio/err2/internal/test"
+)
+
+func TestHandlers(t *testing.T) {
+	t.Parallel()
+	type args struct {
+		f []any // we use any because it's same as real-world case at start
+	}
+	tests := []struct {
+		name string
+		args args
+		want error
+	}{
+		{"one", args{f: []any{err2.Noop}}, err2.ErrNotFound},
+		{"two", args{f: []any{err2.Noop, err2.Noop}}, err2.ErrNotFound},
+		{"three", args{f: []any{err2.Noop, err2.Noop, err2.Noop}}, err2.ErrNotFound},
+		{"reset", args{f: []any{err2.Noop, err2.Noop, err2.Reset}}, nil},
+		{"reset first", args{f: []any{err2.Reset, err2.Noop, err2.Noop}}, nil},
+		{"reset second", args{f: []any{err2.Noop, err2.Reset, err2.Noop}}, nil},
+		{"set new first", args{f: []any{
+			func(error) error { return err2.ErrAlreadyExist }, err2.Noop}}, err2.ErrAlreadyExist},
+		{"set new second", args{f: []any{err2.Noop,
+			func(error) error { return err2.ErrAlreadyExist }, err2.Noop}}, err2.ErrAlreadyExist},
+		{"set new first and reset", args{f: []any{
+			func(error) error { return err2.ErrAlreadyExist }, err2.Reset}}, nil},
+	}
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			anys := tt.args.f
+
+			test.Require(t, anys != nil, "cannot be nil")
+			fns := handler.AssertErrHandlers(anys)
+			test.Require(t, fns != nil, "cannot be nil")
+
+			errHandler := handler.Pipeline(fns)
+			err := errHandler(err2.ErrNotFound)
+			if err == nil {
+				test.Require(t, tt.want == nil)
+			} else {
+				test.RequireEqual(t, err.Error(), tt.want.Error())
+			}
+		})
+	}
+}