example_test.go

Documentation: github.com/google/go-cmp/cmp/cmpopts

     1  // Copyright 2020, 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 cmpopts_test
     6  
     7  import (
     8  	"fmt"
     9  	"net"
    10  	"time"
    11  
    12  	"github.com/google/go-cmp/cmp"
    13  	"github.com/google/go-cmp/cmp/cmpopts"
    14  	"github.com/google/go-cmp/cmp/internal/flags"
    15  )
    16  
    17  func init() {
    18  	flags.Deterministic = true
    19  }
    20  
    21  // Use IgnoreFields to ignore fields on a struct type when comparing
    22  // by providing a value of the type and the field names to ignore.
    23  // Typically, a zero value of the type is used (e.g., foo.MyStruct{}).
    24  func ExampleIgnoreFields_testing() {
    25  	// Let got be the hypothetical value obtained from some logic under test
    26  	// and want be the expected golden data.
    27  	got, want := MakeGatewayInfo()
    28  
    29  	// While the specified fields will be semantically ignored for the comparison,
    30  	// the fields may be printed in the diff when displaying entire values
    31  	// that are already determined to be different.
    32  	if diff := cmp.Diff(want, got, cmpopts.IgnoreFields(Client{}, "IPAddress")); diff != "" {
    33  		t.Errorf("MakeGatewayInfo() mismatch (-want +got):\n%s", diff)
    34  	}
    35  
    36  	// Output:
    37  	// MakeGatewayInfo() mismatch (-want +got):
    38  	//   cmpopts_test.Gateway{
    39  	//   	SSID:      "CoffeeShopWiFi",
    40  	// - 	IPAddress: s"192.168.0.2",
    41  	// + 	IPAddress: s"192.168.0.1",
    42  	//   	NetMask:   s"ffff0000",
    43  	//   	Clients: []cmpopts_test.Client{
    44  	//   		... // 3 identical elements
    45  	//   		{Hostname: "espresso", ...},
    46  	//   		{Hostname: "latte", LastSeen: s"2009-11-10 23:00:23 +0000 UTC", ...},
    47  	// + 		{
    48  	// + 			Hostname:  "americano",
    49  	// + 			IPAddress: s"192.168.0.188",
    50  	// + 			LastSeen:  s"2009-11-10 23:03:05 +0000 UTC",
    51  	// + 		},
    52  	//   	},
    53  	//   }
    54  }
    55  
    56  type (
    57  	Gateway struct {
    58  		SSID      string
    59  		IPAddress net.IP
    60  		NetMask   net.IPMask
    61  		Clients   []Client
    62  	}
    63  	Client struct {
    64  		Hostname  string
    65  		IPAddress net.IP
    66  		LastSeen  time.Time
    67  	}
    68  )
    69  
    70  func MakeGatewayInfo() (x, y Gateway) {
    71  	x = Gateway{
    72  		SSID:      "CoffeeShopWiFi",
    73  		IPAddress: net.IPv4(192, 168, 0, 1),
    74  		NetMask:   net.IPv4Mask(255, 255, 0, 0),
    75  		Clients: []Client{{
    76  			Hostname:  "ristretto",
    77  			IPAddress: net.IPv4(192, 168, 0, 116),
    78  		}, {
    79  			Hostname:  "aribica",
    80  			IPAddress: net.IPv4(192, 168, 0, 104),
    81  			LastSeen:  time.Date(2009, time.November, 10, 23, 6, 32, 0, time.UTC),
    82  		}, {
    83  			Hostname:  "macchiato",
    84  			IPAddress: net.IPv4(192, 168, 0, 153),
    85  			LastSeen:  time.Date(2009, time.November, 10, 23, 39, 43, 0, time.UTC),
    86  		}, {
    87  			Hostname:  "espresso",
    88  			IPAddress: net.IPv4(192, 168, 0, 121),
    89  		}, {
    90  			Hostname:  "latte",
    91  			IPAddress: net.IPv4(192, 168, 0, 219),
    92  			LastSeen:  time.Date(2009, time.November, 10, 23, 0, 23, 0, time.UTC),
    93  		}, {
    94  			Hostname:  "americano",
    95  			IPAddress: net.IPv4(192, 168, 0, 188),
    96  			LastSeen:  time.Date(2009, time.November, 10, 23, 3, 5, 0, time.UTC),
    97  		}},
    98  	}
    99  	y = Gateway{
   100  		SSID:      "CoffeeShopWiFi",
   101  		IPAddress: net.IPv4(192, 168, 0, 2),
   102  		NetMask:   net.IPv4Mask(255, 255, 0, 0),
   103  		Clients: []Client{{
   104  			Hostname:  "ristretto",
   105  			IPAddress: net.IPv4(192, 168, 0, 116),
   106  		}, {
   107  			Hostname:  "aribica",
   108  			IPAddress: net.IPv4(192, 168, 0, 104),
   109  			LastSeen:  time.Date(2009, time.November, 10, 23, 6, 32, 0, time.UTC),
   110  		}, {
   111  			Hostname:  "macchiato",
   112  			IPAddress: net.IPv4(192, 168, 0, 153),
   113  			LastSeen:  time.Date(2009, time.November, 10, 23, 39, 43, 0, time.UTC),
   114  		}, {
   115  			Hostname:  "espresso",
   116  			IPAddress: net.IPv4(192, 168, 0, 121),
   117  		}, {
   118  			Hostname:  "latte",
   119  			IPAddress: net.IPv4(192, 168, 0, 221),
   120  			LastSeen:  time.Date(2009, time.November, 10, 23, 0, 23, 0, time.UTC),
   121  		}},
   122  	}
   123  	return x, y
   124  }
   125  
   126  var t fakeT
   127  
   128  type fakeT struct{}
   129  
   130  func (t fakeT) Errorf(format string, args ...interface{}) { fmt.Printf(format+"\n", args...) }
   131
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