--- /dev/null
+// Copyright 2017, The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cmp_test
+
+import (
+ "fmt"
+ "math"
+ "net"
+ "reflect"
+ "sort"
+ "strings"
+ "time"
+
+ "github.com/google/go-cmp/cmp"
+)
+
+// TODO: Re-write these examples in terms of how you actually use the
+// fundamental options and filters and not in terms of what cool things you can
+// do with them since that overlaps with cmp/cmpopts.
+
+// Use Diff to print out a human-readable report of differences for tests
+// comparing nested or structured data.
+func ExampleDiff_testing() {
+ // Let got be the hypothetical value obtained from some logic under test
+ // and want be the expected golden data.
+ got, want := MakeGatewayInfo()
+
+ if diff := cmp.Diff(want, got); diff != "" {
+ t.Errorf("MakeGatewayInfo() mismatch (-want +got):\n%s", diff)
+ }
+
+ // Output:
+ // MakeGatewayInfo() mismatch (-want +got):
+ // cmp_test.Gateway{
+ // SSID: "CoffeeShopWiFi",
+ // - IPAddress: s"192.168.0.2",
+ // + IPAddress: s"192.168.0.1",
+ // NetMask: {0xff, 0xff, 0x00, 0x00},
+ // Clients: []cmp_test.Client{
+ // ... // 2 identical elements
+ // {Hostname: "macchiato", IPAddress: s"192.168.0.153", LastSeen: s"2009-11-10 23:39:43 +0000 UTC"},
+ // {Hostname: "espresso", IPAddress: s"192.168.0.121"},
+ // {
+ // Hostname: "latte",
+ // - IPAddress: s"192.168.0.221",
+ // + IPAddress: s"192.168.0.219",
+ // LastSeen: s"2009-11-10 23:00:23 +0000 UTC",
+ // },
+ // + {
+ // + Hostname: "americano",
+ // + IPAddress: s"192.168.0.188",
+ // + LastSeen: s"2009-11-10 23:03:05 +0000 UTC",
+ // + },
+ // },
+ // }
+}
+
+// Approximate equality for floats can be handled by defining a custom
+// comparer on floats that determines two values to be equal if they are within
+// some range of each other.
+//
+// This example is for demonstrative purposes; use cmpopts.EquateApprox instead.
+func ExampleOption_approximateFloats() {
+ // This Comparer only operates on float64.
+ // To handle float32s, either define a similar function for that type
+ // or use a Transformer to convert float32s into float64s.
+ opt := cmp.Comparer(func(x, y float64) bool {
+ delta := math.Abs(x - y)
+ mean := math.Abs(x+y) / 2.0
+ return delta/mean < 0.00001
+ })
+
+ x := []float64{1.0, 1.1, 1.2, math.Pi}
+ y := []float64{1.0, 1.1, 1.2, 3.14159265359} // Accurate enough to Pi
+ z := []float64{1.0, 1.1, 1.2, 3.1415} // Diverges too far from Pi
+
+ fmt.Println(cmp.Equal(x, y, opt))
+ fmt.Println(cmp.Equal(y, z, opt))
+ fmt.Println(cmp.Equal(z, x, opt))
+
+ // Output:
+ // true
+ // false
+ // false
+}
+
+// Normal floating-point arithmetic defines == to be false when comparing
+// NaN with itself. In certain cases, this is not the desired property.
+//
+// This example is for demonstrative purposes; use cmpopts.EquateNaNs instead.
+func ExampleOption_equalNaNs() {
+ // This Comparer only operates on float64.
+ // To handle float32s, either define a similar function for that type
+ // or use a Transformer to convert float32s into float64s.
+ opt := cmp.Comparer(func(x, y float64) bool {
+ return (math.IsNaN(x) && math.IsNaN(y)) || x == y
+ })
+
+ x := []float64{1.0, math.NaN(), math.E, -0.0, +0.0}
+ y := []float64{1.0, math.NaN(), math.E, -0.0, +0.0}
+ z := []float64{1.0, math.NaN(), math.Pi, -0.0, +0.0} // Pi constant instead of E
+
+ fmt.Println(cmp.Equal(x, y, opt))
+ fmt.Println(cmp.Equal(y, z, opt))
+ fmt.Println(cmp.Equal(z, x, opt))
+
+ // Output:
+ // true
+ // false
+ // false
+}
+
+// To have floating-point comparisons combine both properties of NaN being
+// equal to itself and also approximate equality of values, filters are needed
+// to restrict the scope of the comparison so that they are composable.
+//
+// This example is for demonstrative purposes;
+// use cmpopts.EquateNaNs and cmpopts.EquateApprox instead.
+func ExampleOption_equalNaNsAndApproximateFloats() {
+ alwaysEqual := cmp.Comparer(func(_, _ interface{}) bool { return true })
+
+ opts := cmp.Options{
+ // This option declares that a float64 comparison is equal only if
+ // both inputs are NaN.
+ cmp.FilterValues(func(x, y float64) bool {
+ return math.IsNaN(x) && math.IsNaN(y)
+ }, alwaysEqual),
+
+ // This option declares approximate equality on float64s only if
+ // both inputs are not NaN.
+ cmp.FilterValues(func(x, y float64) bool {
+ return !math.IsNaN(x) && !math.IsNaN(y)
+ }, cmp.Comparer(func(x, y float64) bool {
+ delta := math.Abs(x - y)
+ mean := math.Abs(x+y) / 2.0
+ return delta/mean < 0.00001
+ })),
+ }
+
+ x := []float64{math.NaN(), 1.0, 1.1, 1.2, math.Pi}
+ y := []float64{math.NaN(), 1.0, 1.1, 1.2, 3.14159265359} // Accurate enough to Pi
+ z := []float64{math.NaN(), 1.0, 1.1, 1.2, 3.1415} // Diverges too far from Pi
+
+ fmt.Println(cmp.Equal(x, y, opts))
+ fmt.Println(cmp.Equal(y, z, opts))
+ fmt.Println(cmp.Equal(z, x, opts))
+
+ // Output:
+ // true
+ // false
+ // false
+}
+
+// Sometimes, an empty map or slice is considered equal to an allocated one
+// of zero length.
+//
+// This example is for demonstrative purposes; use cmpopts.EquateEmpty instead.
+func ExampleOption_equalEmpty() {
+ alwaysEqual := cmp.Comparer(func(_, _ interface{}) bool { return true })
+
+ // This option handles slices and maps of any type.
+ opt := cmp.FilterValues(func(x, y interface{}) bool {
+ vx, vy := reflect.ValueOf(x), reflect.ValueOf(y)
+ return (vx.IsValid() && vy.IsValid() && vx.Type() == vy.Type()) &&
+ (vx.Kind() == reflect.Slice || vx.Kind() == reflect.Map) &&
+ (vx.Len() == 0 && vy.Len() == 0)
+ }, alwaysEqual)
+
+ type S struct {
+ A []int
+ B map[string]bool
+ }
+ x := S{nil, make(map[string]bool, 100)}
+ y := S{make([]int, 0, 200), nil}
+ z := S{[]int{0}, nil} // []int has a single element (i.e., not empty)
+
+ fmt.Println(cmp.Equal(x, y, opt))
+ fmt.Println(cmp.Equal(y, z, opt))
+ fmt.Println(cmp.Equal(z, x, opt))
+
+ // Output:
+ // true
+ // false
+ // false
+}
+
+// Two slices may be considered equal if they have the same elements,
+// regardless of the order that they appear in. Transformations can be used
+// to sort the slice.
+//
+// This example is for demonstrative purposes; use cmpopts.SortSlices instead.
+func ExampleOption_sortedSlice() {
+ // This Transformer sorts a []int.
+ trans := cmp.Transformer("Sort", func(in []int) []int {
+ out := append([]int(nil), in...) // Copy input to avoid mutating it
+ sort.Ints(out)
+ return out
+ })
+
+ x := struct{ Ints []int }{[]int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}}
+ y := struct{ Ints []int }{[]int{2, 8, 0, 9, 6, 1, 4, 7, 3, 5}}
+ z := struct{ Ints []int }{[]int{0, 0, 1, 2, 3, 4, 5, 6, 7, 8}}
+
+ fmt.Println(cmp.Equal(x, y, trans))
+ fmt.Println(cmp.Equal(y, z, trans))
+ fmt.Println(cmp.Equal(z, x, trans))
+
+ // Output:
+ // true
+ // false
+ // false
+}
+
+type otherString string
+
+func (x otherString) Equal(y otherString) bool {
+ return strings.ToLower(string(x)) == strings.ToLower(string(y))
+}
+
+// If the Equal method defined on a type is not suitable, the type can be
+// dynamically transformed to be stripped of the Equal method (or any method
+// for that matter).
+func ExampleOption_avoidEqualMethod() {
+ // Suppose otherString.Equal performs a case-insensitive equality,
+ // which is too loose for our needs.
+ // We can avoid the methods of otherString by declaring a new type.
+ type myString otherString
+
+ // This transformer converts otherString to myString, allowing Equal to use
+ // other Options to determine equality.
+ trans := cmp.Transformer("", func(in otherString) myString {
+ return myString(in)
+ })
+
+ x := []otherString{"foo", "bar", "baz"}
+ y := []otherString{"fOO", "bAr", "Baz"} // Same as before, but with different case
+
+ fmt.Println(cmp.Equal(x, y)) // Equal because of case-insensitivity
+ fmt.Println(cmp.Equal(x, y, trans)) // Not equal because of more exact equality
+
+ // Output:
+ // true
+ // false
+}
+
+func roundF64(z float64) float64 {
+ if z < 0 {
+ return math.Ceil(z - 0.5)
+ }
+ return math.Floor(z + 0.5)
+}
+
+// The complex numbers complex64 and complex128 can really just be decomposed
+// into a pair of float32 or float64 values. It would be convenient to be able
+// define only a single comparator on float64 and have float32, complex64, and
+// complex128 all be able to use that comparator. Transformations can be used
+// to handle this.
+func ExampleOption_transformComplex() {
+ opts := []cmp.Option{
+ // This transformer decomposes complex128 into a pair of float64s.
+ cmp.Transformer("T1", func(in complex128) (out struct{ Real, Imag float64 }) {
+ out.Real, out.Imag = real(in), imag(in)
+ return out
+ }),
+ // This transformer converts complex64 to complex128 to allow the
+ // above transform to take effect.
+ cmp.Transformer("T2", func(in complex64) complex128 {
+ return complex128(in)
+ }),
+ // This transformer converts float32 to float64.
+ cmp.Transformer("T3", func(in float32) float64 {
+ return float64(in)
+ }),
+ // This equality function compares float64s as rounded integers.
+ cmp.Comparer(func(x, y float64) bool {
+ return roundF64(x) == roundF64(y)
+ }),
+ }
+
+ x := []interface{}{
+ complex128(3.0), complex64(5.1 + 2.9i), float32(-1.2), float64(12.3),
+ }
+ y := []interface{}{
+ complex128(3.1), complex64(4.9 + 3.1i), float32(-1.3), float64(11.7),
+ }
+ z := []interface{}{
+ complex128(3.8), complex64(4.9 + 3.1i), float32(-1.3), float64(11.7),
+ }
+
+ fmt.Println(cmp.Equal(x, y, opts...))
+ fmt.Println(cmp.Equal(y, z, opts...))
+ fmt.Println(cmp.Equal(z, x, opts...))
+
+ // Output:
+ // true
+ // false
+ // false
+}
+
+type (
+ Gateway struct {
+ SSID string
+ IPAddress net.IP
+ NetMask net.IPMask
+ Clients []Client
+ }
+ Client struct {
+ Hostname string
+ IPAddress net.IP
+ LastSeen time.Time
+ }
+)
+
+func MakeGatewayInfo() (x, y Gateway) {
+ x = Gateway{
+ SSID: "CoffeeShopWiFi",
+ IPAddress: net.IPv4(192, 168, 0, 1),
+ NetMask: net.IPv4Mask(255, 255, 0, 0),
+ Clients: []Client{{
+ Hostname: "ristretto",
+ IPAddress: net.IPv4(192, 168, 0, 116),
+ }, {
+ Hostname: "aribica",
+ IPAddress: net.IPv4(192, 168, 0, 104),
+ LastSeen: time.Date(2009, time.November, 10, 23, 6, 32, 0, time.UTC),
+ }, {
+ Hostname: "macchiato",
+ IPAddress: net.IPv4(192, 168, 0, 153),
+ LastSeen: time.Date(2009, time.November, 10, 23, 39, 43, 0, time.UTC),
+ }, {
+ Hostname: "espresso",
+ IPAddress: net.IPv4(192, 168, 0, 121),
+ }, {
+ Hostname: "latte",
+ IPAddress: net.IPv4(192, 168, 0, 219),
+ LastSeen: time.Date(2009, time.November, 10, 23, 0, 23, 0, time.UTC),
+ }, {
+ Hostname: "americano",
+ IPAddress: net.IPv4(192, 168, 0, 188),
+ LastSeen: time.Date(2009, time.November, 10, 23, 3, 5, 0, time.UTC),
+ }},
+ }
+ y = Gateway{
+ SSID: "CoffeeShopWiFi",
+ IPAddress: net.IPv4(192, 168, 0, 2),
+ NetMask: net.IPv4Mask(255, 255, 0, 0),
+ Clients: []Client{{
+ Hostname: "ristretto",
+ IPAddress: net.IPv4(192, 168, 0, 116),
+ }, {
+ Hostname: "aribica",
+ IPAddress: net.IPv4(192, 168, 0, 104),
+ LastSeen: time.Date(2009, time.November, 10, 23, 6, 32, 0, time.UTC),
+ }, {
+ Hostname: "macchiato",
+ IPAddress: net.IPv4(192, 168, 0, 153),
+ LastSeen: time.Date(2009, time.November, 10, 23, 39, 43, 0, time.UTC),
+ }, {
+ Hostname: "espresso",
+ IPAddress: net.IPv4(192, 168, 0, 121),
+ }, {
+ Hostname: "latte",
+ IPAddress: net.IPv4(192, 168, 0, 221),
+ LastSeen: time.Date(2009, time.November, 10, 23, 0, 23, 0, time.UTC),
+ }},
+ }
+ return x, y
+}
+
+var t fakeT
+
+type fakeT struct{}
+
+func (t fakeT) Errorf(format string, args ...interface{}) { fmt.Printf(format+"\n", args...) }
projects / dotfiles / .git / blobdiff