assert: guard CanConvert call in backward compatible wrapper

Author: torkelrogstad

assert/assertion_compare.go

@@ -306,7 +306,7 @@ func compare(obj1, obj2 interface{}, kind reflect.Kind) (CompareType, bool) {
 	case reflect.Struct:
 		{
 			// All structs enter here. We're not interested in most types.
-			if !obj1Value.CanConvert(timeType) {
+			if !canConvert(obj1Value, timeType) {
 				break
 			}
 

assert/assertion_compare_can_convert.go

@@ -0,0 +1,11 @@
+// +build go1.17
+
+package assert
+
+import "reflect"
+
+// Wrapper around reflect.Value.CanConvert, for compatability
+// reasons.
+func canConvert(value reflect.Value, to reflect.Type) bool {
+	return value.CanConvert(to)
+}

assert/assertion_compare_go1.17_test.go

@@ -0,0 +1,49 @@
+// +build go1.17
+
+package assert
+
+import (
+	"reflect"
+	"testing"
+	"time"
+)
+
+func TestCompare17(t *testing.T) {
+	type customTime time.Time
+	for _, currCase := range []struct {
+		less    interface{}
+		greater interface{}
+		cType   string
+	}{
+		{less: time.Now(), greater: time.Now().Add(time.Hour), cType: "time.Time"},
+		{less: customTime(time.Now()), greater: customTime(time.Now().Add(time.Hour)), cType: "time.Time"},
+	} {
+		resLess, isComparable := compare(currCase.less, currCase.greater, reflect.ValueOf(currCase.less).Kind())
+		if !isComparable {
+			t.Error("object should be comparable for type " + currCase.cType)
+		}
+
+		if resLess != compareLess {
+			t.Errorf("object less (%v) should be less than greater (%v) for type "+currCase.cType,
+				currCase.less, currCase.greater)
+		}
+
+		resGreater, isComparable := compare(currCase.greater, currCase.less, reflect.ValueOf(currCase.less).Kind())
+		if !isComparable {
+			t.Error("object are comparable for type " + currCase.cType)
+		}
+
+		if resGreater != compareGreater {
+			t.Errorf("object greater should be greater than less for type " + currCase.cType)
+		}
+
+		resEqual, isComparable := compare(currCase.less, currCase.less, reflect.ValueOf(currCase.less).Kind())
+		if !isComparable {
+			t.Error("object are comparable for type " + currCase.cType)
+		}
+
+		if resEqual != 0 {
+			t.Errorf("objects should be equal for type " + currCase.cType)
+		}
+	}
+}

assert/assertion_compare_legacy.go

@@ -0,0 +1,11 @@
+// +build !go1.17
+
+package assert
+
+import "reflect"
+
+// Older versions of Go does not have the reflect.Value.CanConvert
+// method.
+func canConvert(value reflect.Value, to reflect.Type) bool {
+	return false
+}

assert/assertion_compare_test.go

@@ -6,7 +6,6 @@ import (
 	"reflect"
 	"runtime"
 	"testing"
-	"time"
 )
 
 func TestCompare(t *testing.T) {
@@ -23,7 +22,6 @@ func TestCompare(t *testing.T) {
 	type customFloat32 float32
 	type customFloat64 float64
 	type customString string
-	type customTime time.Time
 	for _, currCase := range []struct {
 		less    interface{}
 		greater interface{}
@@ -54,8 +52,6 @@ func TestCompare(t *testing.T) {
 		{less: customFloat32(1.23), greater: customFloat32(2.23), cType: "float32"},
 		{less: float64(1.23), greater: float64(2.34), cType: "float64"},
 		{less: customFloat64(1.23), greater: customFloat64(2.34), cType: "float64"},
-		{less: time.Now(), greater: time.Now().Add(time.Hour), cType: "time.Time"},
-		{less: customTime(time.Now()), greater: customTime(time.Now().Add(time.Hour)), cType: "time.Time"},
 	} {
 		resLess, isComparable := compare(currCase.less, currCase.greater, reflect.ValueOf(currCase.less).Kind())
 		if !isComparable {