errors_test.go

     1  // Copyright 2011 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  	"fmt"
    10  	"testing"
    11  )
    12  
    13  func TestNewEqual(t *testing.T) {
    14  	// Different allocations should not be equal.
    15  	if errors.New("abc") == errors.New("abc") {
    16  		t.Errorf(`New("abc") == New("abc")`)
    17  	}
    18  	if errors.New("abc") == errors.New("xyz") {
    19  		t.Errorf(`New("abc") == New("xyz")`)
    20  	}
    21  
    22  	// Same allocation should be equal to itself (not crash).
    23  	err := errors.New("jkl")
    24  	if err != err {
    25  		t.Errorf(`err != err`)
    26  	}
    27  }
    28  
    29  func TestErrorMethod(t *testing.T) {
    30  	err := errors.New("abc")
    31  	if err.Error() != "abc" {
    32  		t.Errorf(`New("abc").Error() = %q, want %q`, err.Error(), "abc")
    33  	}
    34  }
    35  
    36  func ExampleNew() {
    37  	err := errors.New("emit macho dwarf: elf header corrupted")
    38  	if err != nil {
    39  		fmt.Print(err)
    40  	}
    41  	// Output: emit macho dwarf: elf header corrupted
    42  }
    43  
    44  // The fmt package's Errorf function lets us use the package's formatting
    45  // features to create descriptive error messages.
    46  func ExampleNew_errorf() {
    47  	const name, id = "bimmler", 17
    48  	err := fmt.Errorf("user %q (id %d) not found", name, id)
    49  	if err != nil {
    50  		fmt.Print(err)
    51  	}
    52  	// Output: user "bimmler" (id 17) not found
    53  }
    54  
    55  func ExampleJoin() {
    56  	err1 := errors.New("err1")
    57  	err2 := errors.New("err2")
    58  	err := errors.Join(err1, err2)
    59  	fmt.Println(err)
    60  	if errors.Is(err, err1) {
    61  		fmt.Println("err is err1")
    62  	}
    63  	if errors.Is(err, err2) {
    64  		fmt.Println("err is err2")
    65  	}
    66  	// Output:
    67  	// err1
    68  	// err2
    69  	// err is err1
    70  	// err is err2
    71  }
    72
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