join_test.go

     1  // Copyright 2022 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package errors_test
     6  
     7  import (
     8  	"errors"
     9  	"reflect"
    10  	"testing"
    11  )
    12  
    13  func TestJoinReturnsNil(t *testing.T) {
    14  	if err := errors.Join(); err != nil {
    15  		t.Errorf("errors.Join() = %v, want nil", err)
    16  	}
    17  	if err := errors.Join(nil); err != nil {
    18  		t.Errorf("errors.Join(nil) = %v, want nil", err)
    19  	}
    20  	if err := errors.Join(nil, nil); err != nil {
    21  		t.Errorf("errors.Join(nil, nil) = %v, want nil", err)
    22  	}
    23  }
    24  
    25  func TestJoin(t *testing.T) {
    26  	err1 := errors.New("err1")
    27  	err2 := errors.New("err2")
    28  	for _, test := range []struct {
    29  		errs []error
    30  		want []error
    31  	}{{
    32  		errs: []error{err1},
    33  		want: []error{err1},
    34  	}, {
    35  		errs: []error{err1, err2},
    36  		want: []error{err1, err2},
    37  	}, {
    38  		errs: []error{err1, nil, err2},
    39  		want: []error{err1, err2},
    40  	}} {
    41  		got := errors.Join(test.errs...).(interface{ Unwrap() []error }).Unwrap()
    42  		if !reflect.DeepEqual(got, test.want) {
    43  			t.Errorf("Join(%v) = %v; want %v", test.errs, got, test.want)
    44  		}
    45  		if len(got) != cap(got) {
    46  			t.Errorf("Join(%v) returns errors with len=%v, cap=%v; want len==cap", test.errs, len(got), cap(got))
    47  		}
    48  	}
    49  }
    50  
    51  func TestJoinErrorMethod(t *testing.T) {
    52  	err1 := errors.New("err1")
    53  	err2 := errors.New("err2")
    54  	for _, test := range []struct {
    55  		errs []error
    56  		want string
    57  	}{{
    58  		errs: []error{err1},
    59  		want: "err1",
    60  	}, {
    61  		errs: []error{err1, err2},
    62  		want: "err1\nerr2",
    63  	}, {
    64  		errs: []error{err1, nil, err2},
    65  		want: "err1\nerr2",
    66  	}} {
    67  		got := errors.Join(test.errs...).Error()
    68  		if got != test.want {
    69  			t.Errorf("Join(%v).Error() = %q; want %q", test.errs, got, test.want)
    70  		}
    71  	}
    72  }
    73
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