Merge 12bd6d1 into bbf6a5b

multierror/README.md

@@ -0,0 +1,21 @@
+# Usage
+
+MultiError concatenate errors into one error.
+
+## Example
+```go 
+package main 
+
+import (
+	"github.com/donutloop/toolkit/multierror"
+	"fmt"
+)
+
+func main() {
+    errs := []error{
+		errors.New("error connect to db failed"),
+		errors.New("error marschaling json"),
+    }
+    fmt.Println(multierror.New(errs...))
+}
+```

multierror/doc_test.go

@@ -0,0 +1,18 @@
+package multierror_test
+
+import (
+	"fmt"
+
+	"errors"
+
+	"github.com/donutloop/toolkit/multierror"
+)
+
+func ExampleMultiError() {
+	errs := []error{
+		errors.New("error connect to db failed"),
+		errors.New("error marschaling json"),
+	}
+	fmt.Println(multierror.New(errs...))
+	// Output: multiple errors: error connect to db failed; error marschaling json
+}

multierror/muliterror.go

@@ -0,0 +1,44 @@
+package multierror
+
+import "bytes"
+
+// New concatenate errors into one.
+// If all errors are nil then it will returns nil
+// otherwise the return value is a MultiError containing all the non-nil error.
+func New(errs ...error) error {
+	if len(errs) == 0 {
+		return nil
+	}
+	errBucket := make([]error, 0, len(errs)/2)
+	for _, err := range errs {
+		if err != nil {
+			errBucket = append(errBucket, err)
+		}
+	}
+	if len(errBucket) == 0 {
+		return nil
+	}
+	return multiError{errBucket}
+}
+
+// MultiError concatenate errors into one error.
+type multiError struct {
+	Errors []error
+}
+
+func (es multiError) Error() string {
+	switch len(es.Errors) {
+	case 1:
+		return es.Errors[0].Error()
+	default:
+		var buf bytes.Buffer
+		buf.WriteString("multiple errors: ")
+		for i, e := range es.Errors {
+			if i > 0 {
+				buf.WriteString("; ")
+			}
+			buf.WriteString(e.Error())
+		}
+		return buf.String()
+	}
+}

multierror/muliterror_test.go

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+package multierror_test
+
+import (
+	"errors"
+
+	"testing"
+
+	"github.com/donutloop/toolkit/multierror"
+)
+
+func TestMultiError_Error(t *testing.T) {
+	errs := []error{
+		nil,
+		errors.New("error connect to db failed"),
+		errors.New("error marschaling json"),
+	}
+	expectedValue := "multiple errors: error connect to db failed; error marschaling json"
+	err := multierror.New(errs...)
+	if err.Error() != expectedValue {
+		t.Errorf(`unexpected error message (actual:"%s", expected: "%s")`, err.Error(), expectedValue)
+	}
+}