Support versions of Go down to Go1.6 (#3)

Avoid any features introduced in newer versions such as: * testing.T.Run * sort.Slice * sort.SliceStable * sort.IsSliceSorted Fixes #2

Author: dsnet

.travis.yml

@@ -1,5 +1,5 @@
 sudo: false
 language: go
-# TODO(light): Enable Go 1.6 (#2).
 go:
+- 1.6
 - 1.x

cmp/compare.go

@@ -28,7 +28,6 @@ package cmp
 import (
 "fmt"
 "reflect"
-"sort"
 )
 
 // BUG: Maps with keys containing NaN values cannot be properly compared due to
@@ -126,10 +125,13 @@ func newState(opts []Option) *state {
 for _, opt := range opts {
 s.processOption(opt)
 }
-// Sort options such that Ignore options are evaluated first.
-sort.SliceStable(s.opts, func(i, j int) bool {
-return s.opts[i].op == nil && s.opts[j].op != nil
-})
+// Move Ignore options to the front so that they are evaluated first.
+for i, j := 0, 0; i < len(s.opts); i++ {
+if s.opts[i].op == nil {
+s.opts[i], s.opts[j] = s.opts[j], s.opts[i]
+j++
+}
+}
 return s
 }
 

cmp/compare_test.go

@@ -83,7 +83,7 @@ func TestDiff(t *testing.T) {
 tests = append(tests, project4Tests()...)
 
 for _, tt := range tests {
-t.Run(tt.label, func(t *testing.T) {
+tRun(t, tt.label, func(t *testing.T) {
 var gotDiff, gotPanic string
 func() {
 defer func() {
@@ -1444,22 +1444,22 @@ func project1Tests() []test {
 }}
 }
 
+type germSorter []*pb.Germ
+
+func (gs germSorter) Len() int { return len(gs) }
+func (gs germSorter) Less(i, j int) bool { return gs[i].String() < gs[j].String() }
+func (gs germSorter) Swap(i, j int) { gs[i], gs[j] = gs[j], gs[i] }
+
 func project2Tests() []test {
 const label = "Project2"
 
 sortGerms := cmp.FilterValues(func(x, y []*pb.Germ) bool {
-ok1 := sort.SliceIsSorted(x, func(i, j int) bool {
-return x[i].String() < x[j].String()
-})
-ok2 := sort.SliceIsSorted(y, func(i, j int) bool {
-return y[i].String() < y[j].String()
-})
+ok1 := sort.IsSorted(germSorter(x))
+ok2 := sort.IsSorted(germSorter(y))
 return !ok1 || !ok2
 }, cmp.Transformer("Sort", func(in []*pb.Germ) []*pb.Germ {
 out := append([]*pb.Germ(nil), in...) // Make copy
-sort.Slice(out, func(i, j int) bool {
-return out[i].String() < out[j].String()
-})
+sort.Sort(germSorter(out))
 return out
 }))
 
@@ -1759,3 +1759,17 @@ func project4Tests() []test {
 +: <non-existent>`,
 }}
 }
+
+// TODO: Delete this hack when we drop Go1.6 support.
+func tRun(t *testing.T, name string, f func(t *testing.T)) {
+type runner interface {
+Run(string, func(t *testing.T)) bool
+}
+var ti interface{} = t
+if r, ok := ti.(runner); ok {
+r.Run(name, f)
+} else {
+t.Logf("Test: %s", name)
+f(t)
+}
+}

cmp/example_test.go

@@ -10,7 +10,6 @@ import (
 "reflect"
 "sort"
 "strings"
-"time"
 
 "github.com/google/go-cmp/cmp"
 )
@@ -135,56 +134,6 @@ func ExampleOption_equalEmpty() {
 // false
 }
 
-// Equal compares map keys using Go's == operator. To use Equal itself on
-// map keys, transform the map into something else, like a slice of
-// key-value pairs.
-func ExampleOption_transformMap() {
-type KV struct {
-K time.Time
-V string
-}
-// This transformer flattens the map as a slice of sorted key-value pairs.
-// We can now safely rely on the Time.Equal to be used for equality.
-trans := cmp.Transformer("", func(m map[time.Time]string) (s []KV) {
-for k, v := range m {
-s = append(s, KV{k, v})
-}
-sort.Slice(s, func(i, j int) bool {
-return s[i].K.Before(s[j].K)
-})
-return s
-})
-
-t1 := time.Date(2009, time.November, 10, 23, 0, 0, 0, time.UTC)
-t2 := time.Date(2010, time.November, 10, 23, 0, 0, 0, time.UTC)
-t3 := time.Date(2011, time.November, 10, 23, 0, 0, 0, time.UTC)
-
-x := map[time.Time]string{
-t1.In(time.UTC): "0th birthday",
-t2.In(time.UTC): "1st birthday",
-t3.In(time.UTC): "2nd birthday",
-}
-y := map[time.Time]string{
-t1.In(time.Local): "0th birthday",
-t2.In(time.Local): "1st birthday",
-t3.In(time.Local): "2nd birthday",
-}
-z := map[time.Time]string{
-time.Now(): "a long long",
-time.Now(): "time ago",
-time.Now(): "in a galaxy far far away",
-}
-
-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
-}
-
 // 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.

cmp/options_test.go

@@ -185,7 +185,7 @@ func TestOptionPanic(t *testing.T) {
 }}
 
 for _, tt := range tests {
-t.Run(tt.label, func(t *testing.T) {
+tRun(t, tt.label, func(t *testing.T) {
 var gotPanic string
 func() {
 defer func() {
@@ -215,3 +215,17 @@ func TestOptionPanic(t *testing.T) {
 })
 }
 }
+
+// TODO: Delete this hack when we drop Go1.6 support.
+func tRun(t *testing.T, name string, f func(t *testing.T)) {
+type runner interface {
+Run(string, func(t *testing.T)) bool
+}
+var ti interface{} = t
+if r, ok := ti.(runner); ok {
+r.Run(name, f)
+} else {
+t.Logf("Test: %s", name)
+f(t)
+}
+}

cmp/reporter.go

@@ -385,8 +385,8 @@ func sortKeys(vs []reflect.Value) []reflect.Value {
 return vs
 }
 
-// Sort the map keys
-sort.Slice(vs, func(i, j int) bool { return isLess(vs[i], vs[j]) })
+// Sort the map keys.
+sort.Sort(valueSorter(vs))
 
 // Deduplicate keys (fails for NaNs).
 vs2 := vs[:1]
@@ -397,3 +397,10 @@ func sortKeys(vs []reflect.Value) []reflect.Value {
 }
 return vs2
 }
+
+// TODO: Use sort.Slice once Google AppEngine is on Go1.8 or above.
+type valueSorter []reflect.Value
+
+func (vs valueSorter) Len() int { return len(vs) }
+func (vs valueSorter) Less(i, j int) bool { return isLess(vs[i], vs[j]) }
+func (vs valueSorter) Swap(i, j int) { vs[i], vs[j] = vs[j], vs[i] }