assert.Empty: refactor using reflect.Value.IsZero()

dolmen · dolmen · commit 49f6d4509a38 · 2025-06-03T14:53:44.000+02:00
Simplify isEmptyValue (used by assert.Empty) by checking early if the
value is the zero value of the type using reflect.Value.IsZero
(available since Go 1.13, so after the initial assert.Empty implementation).
isEmpty is now faster.

go test -bench Benchmark_isEmpty
goos: darwin
goarch: arm64
pkg: github.com/stretchr/testify/assert
cpu: Apple M2

Before:
  Benchmark_isEmpty-8   	15841243	       77.27 ns/op	      8 B/op	      1 allocs/op
After
  Benchmark_isEmpty-8   	50665512	       21.08 ns/op	      0 B/op	      0 allocs/op
diff --git a/assert/assertions.go b/assert/assertions.go
@@ -757,22 +757,20 @@ func isEmpty(object interface{}) bool {
 
 // isEmptyValue gets whether the specified reflect.Value is considered empty or not.
 func isEmptyValue(objValue reflect.Value) bool {
+	if objValue.IsZero() {
+		return true
+	}
+	// Special cases of non-zero values that we consider empty
 	switch objValue.Kind() {
 	// collection types are empty when they have no element
+	// Note: array types are empty when they match their zero-initialized state.
 	case reflect.Chan, reflect.Map, reflect.Slice:
 		return objValue.Len() == 0
-	// pointers are empty if nil or if the value they point to is empty
+	// non-nil pointers are empty if the value they point to is empty
 	case reflect.Ptr:
-		if objValue.IsNil() {
-			return true
-		}
 		return isEmptyValue(objValue.Elem())
-	// for all other types, compare against the zero value
-	// array types are empty when they match their zero-initialized state
-	default:
-		zero := reflect.Zero(objValue.Type())
-		return reflect.DeepEqual(objValue.Interface(), zero.Interface())
 	}
+	return false
 }
 
 // Empty asserts that the given value is "empty".
