github.com/cockroachdb/errors@v1.11.1/errbase/unwrap_test.go (about)

     1  // Copyright 2019 The Cockroach Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
    12  // implied. See the License for the specific language governing
    13  // permissions and limitations under the License.
    14  
    15  package errbase_test
    16  
    17  import (
    18  	"errors"
    19  	"fmt"
    20  	"testing"
    21  
    22  	"github.com/cockroachdb/errors/errbase"
    23  	"github.com/cockroachdb/errors/testutils"
    24  	pkgErr "github.com/pkg/errors"
    25  )
    26  
    27  // This test demonstrates how to use errbase.UnwrapOnce and errbase.UnwrapAll to
    28  // access causes.
    29  func TestUnwrap(t *testing.T) {
    30  	tt := testutils.T{T: t}
    31  
    32  	err := errors.New("hello")
    33  
    34  	tt.CheckEqual(errbase.UnwrapOnce(err), nil)
    35  	tt.CheckEqual(errbase.UnwrapAll(err), err)
    36  
    37  	// WithMessage is guaranteed to add just one layer of wrapping.
    38  	err2 := pkgErr.WithMessage(err, "woo")
    39  
    40  	tt.CheckEqual(errbase.UnwrapOnce(err2), err)
    41  	tt.CheckEqual(errbase.UnwrapAll(err2), err)
    42  
    43  	err3 := pkgErr.WithMessage(err2, "woo")
    44  
    45  	tt.CheckEqual(errbase.UnwrapOnce(err3), err2)
    46  	tt.CheckEqual(errbase.UnwrapAll(err3), err)
    47  }
    48  
    49  // This test demonstrates how errbase.UnwrapOnce/errbase.UnwrapAll are able to use
    50  // either Cause() or errbase.Unwrap().
    51  func TestMixedErrorWrapping(t *testing.T) {
    52  	tt := testutils.T{T: t}
    53  
    54  	err := errors.New("hello")
    55  	err2 := pkgErr.WithMessage(err, "woo")
    56  	err3 := &myWrapper{cause: err2}
    57  
    58  	tt.CheckEqual(errbase.UnwrapOnce(err3), err2)
    59  	tt.CheckEqual(errbase.UnwrapAll(err3), err)
    60  }
    61  
    62  func TestMultiErrorUnwrap(t *testing.T) {
    63  	tt := testutils.T{T: t}
    64  
    65  	err := errors.New("hello")
    66  	err2 := pkgErr.WithMessage(err, "woo")
    67  	err3 := fmt.Errorf("%w %w", err, err2)
    68  
    69  	tt.CheckEqual(errbase.UnwrapOnce(err3), nil)
    70  	tt.CheckEqual(errbase.UnwrapAll(err3), err3)
    71  	tt.CheckDeepEqual(errbase.UnwrapMulti(err3), []error{err, err2})
    72  }
    73  
    74  type myWrapper struct{ cause error }
    75  
    76  func (w *myWrapper) Error() string { return w.cause.Error() }
    77  func (w *myWrapper) Unwrap() error { return w.cause }