Add EqualsWithNaN to testutil (#3)

* Add EqualsWithNaN to testutil

Signed-off-by: Saswata Mukherjee <[email protected]>

* Make API cleaner

Signed-off-by: Saswata Mukherjee <[email protected]>

* Rename to WithGoCmp

Signed-off-by: Saswata Mukherjee <[email protected]>

* Add comment

Signed-off-by: Saswata Mukherjee <[email protected]>

Signed-off-by: Saswata Mukherjee <[email protected]>

README.md

@@ -2,7 +2,7 @@
 
 [![core module docs](https://img.shields.io/badge/go.dev-reference-007d9c?logo=go&logoColor=white&style=flat-square)](https://pkg.go.dev/github.com/efficientgo/core)
 
-Go module with set of core packages **every** Go project needs. Minimal API, battle-tested, strictly versioned and with only one transient dependency--[davecgh/go-spew](https://github.com/davecgh/go-spew).
+Go module with set of core packages **every** Go project needs. Minimal API, battle-tested, strictly versioned and with only two transient dependencies-- [davecgh/go-spew](https://github.com/davecgh/go-spew) and [google/go-cmp](https://github.com/google/go-cmp).
 
 Maintained by experienced Go developers, including author of the [Efficient Go book](https://www.oreilly.com/library/view/efficient-go/9781098105709/).
 

go.mod

@@ -2,4 +2,7 @@ module github.com/efficientgo/core
 
 go 1.17
 
-require github.com/davecgh/go-spew v1.1.1
+require (
+	github.com/davecgh/go-spew v1.1.1
+	github.com/google/go-cmp v0.5.9
+)

go.sum

@@ -1,2 +1,4 @@
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
+github.com/google/go-cmp v0.5.9/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=

testutil/testutil.go

@@ -14,6 +14,7 @@ import (
 	"github.com/davecgh/go-spew/spew"
 	"github.com/efficientgo/core/errors"
 	"github.com/efficientgo/core/testutil/internal"
+	"github.com/google/go-cmp/cmp"
 )
 
 // Assert fails the test if the condition is false.
@@ -76,6 +77,33 @@ func Equals(tb testing.TB, exp, act interface{}, v ...interface{}) {
 	tb.Fatal(sprintfWithLimit("\033[31m%s:%d:"+msg+"\n\n\texp: %#v\n\n\tgot: %#v%s\033[39m\n\n", filepath.Base(file), line, exp, act, diff(exp, act)))
 }
 
+type goCmp struct {
+	opts cmp.Options
+}
+
+// WithGoCmp allows specifying options and using https://github.com/google/go-cmp
+// for equality comparisons. The compatibility guarantee of this function's arguments
+// are the same as go-cmp i.e none due to v0.x.
+func WithGoCmp(opts ...cmp.Option) goCmp {
+	return goCmp{opts: opts}
+}
+
+// Equals uses go-cmp for comparing equality between two structs, and can be used with
+// various options defined in go-cmp/cmp and go-cmp/cmp/cmpopts.
+func (o goCmp) Equals(tb testing.TB, exp, act interface{}, v ...interface{}) {
+	tb.Helper()
+	if cmp.Equal(exp, act, o.opts) {
+		return
+	}
+	_, file, line, _ := runtime.Caller(1)
+
+	var msg string
+	if len(v) > 0 {
+		msg = fmt.Sprintf(v[0].(string), v[1:]...)
+	}
+	tb.Fatal(sprintfWithLimit("\033[31m%s:%d:"+msg+"\n\n\texp: %#v\n\n\tgot: %#v%s\033[39m\n\n", filepath.Base(file), line, exp, act, diff(exp, act)))
+}
+
 // FaultOrPanicToErr returns error if panic of fault was triggered during execution of function.
 func FaultOrPanicToErr(f func()) (err error) {
 	// Set this go routine to panic on segfault to allow asserting on those.

testutil/testutil_test.go

@@ -3,7 +3,13 @@
 
 package testutil
 
-import "testing"
+import (
+	"math"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/google/go-cmp/cmp/cmpopts"
+)
 
 func TestContains(t *testing.T) {
 	tests := map[string]struct {
@@ -68,3 +74,53 @@ func TestContains(t *testing.T) {
 		})
 	}
 }
+
+type child struct {
+	Val float64
+}
+
+type parent struct {
+	C child
+}
+
+type unexp struct {
+	val float64
+}
+
+func TestEqualsWithNaN(t *testing.T) {
+	for _, tc := range []struct {
+		name string
+		a    interface{}
+		b    interface{}
+		opts cmp.Options
+	}{
+		{
+			a:    math.NaN(),
+			b:    math.NaN(),
+			name: "Simple NaN value comparison",
+			opts: cmp.Options{cmpopts.EquateNaNs()},
+		},
+		{
+			a:    child{Val: math.NaN()},
+			b:    child{Val: math.NaN()},
+			name: "NaN value as struct member comparison",
+			opts: cmp.Options{cmpopts.EquateNaNs()},
+		},
+		{
+			a:    parent{C: child{Val: math.NaN()}},
+			b:    parent{C: child{Val: math.NaN()}},
+			name: "NaN value in nested struct comparison",
+			opts: cmp.Options{cmpopts.EquateNaNs()},
+		},
+		{
+			a:    unexp{val: math.NaN()},
+			b:    unexp{val: math.NaN()},
+			name: "NaN value as unexported struct member comparison",
+			opts: cmp.Options{cmp.AllowUnexported(unexp{}), cmpopts.EquateNaNs()},
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			WithGoCmp(tc.opts).Equals(t, tc.a, tc.b)
+		})
+	}
+}