assert: allow comparing time.Time

assert/assertion_compare.go

@@ -3,6 +3,7 @@ package assert
 import (
 	"fmt"
 	"reflect"
+	"time"
 )
 
 type CompareType int
@@ -30,6 +31,8 @@ var (
 	float64Type = reflect.TypeOf(float64(1))
 
 	stringType = reflect.TypeOf("")
+
+	timeType = reflect.TypeOf(time.Time{})
 )
 
 func compare(obj1, obj2 interface{}, kind reflect.Kind) (CompareType, bool) {
@@ -299,6 +302,27 @@ func compare(obj1, obj2 interface{}, kind reflect.Kind) (CompareType, bool) {
 				return compareLess, true
 			}
 		}
+	// Check for known struct types we can check for compare results.
+	case reflect.Struct:
+		{
+			// All structs enter here. We're not interested in most types.
+			if !canConvert(obj1Value, timeType) {
+				break
+			}
+
+			// time.Time can compared!
+			timeObj1, ok := obj1.(time.Time)
+			if !ok {
+				timeObj1 = obj1Value.Convert(timeType).Interface().(time.Time)
+			}
+
+			timeObj2, ok := obj2.(time.Time)
+			if !ok {
+				timeObj2 = obj2Value.Convert(timeType).Interface().(time.Time)
+			}
+
+			return compare(timeObj1.UnixNano(), timeObj2.UnixNano(), reflect.Int64)
+		}
 	}
 
 	return compareEqual, false

assert/assertion_compare_can_convert.go

@@ -0,0 +1,16 @@
+//go:build go1.17
+// +build go1.17
+
+// TODO: once support for Go 1.16 is dropped, this file can be
+//       merged/removed with assertion_compare_go1.17_test.go and
+//       assertion_compare_legacy.go
+
+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 +1,54 @@
+//go:build go1.17
+// +build go1.17
+
+// TODO: once support for Go 1.16 is dropped, this file can be
+//       merged/removed with assertion_compare_can_convert.go and
+//       assertion_compare_legacy.go
+
+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 +1,16 @@
+//go:build !go1.17
+// +build !go1.17
+
+// TODO: once support for Go 1.16 is dropped, this file can be
+//       merged/removed with assertion_compare_go1.17_test.go and
+//       assertion_compare_can_convert.go
+
+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

@@ -59,7 +59,8 @@ func TestCompare(t *testing.T) {
 		}
 
 		if resLess != compareLess {
-			t.Errorf("object less should be less than greater for type " + currCase.cType)
+			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())