From 88a414d0725774f245f045f12aee6b94ea66e2f6 Mon Sep 17 00:00:00 2001
From: Vincent Cote-Roy <vincentcr@gmail.com>
Date: Sun, 10 Dec 2017 12:56:05 -0500
Subject: [PATCH] generalize Empty assertion

Make `Empty` work against any struct and custom types, by replacing
explicit zero value comparisons with a `DeepEqual` comparison with
the type's `reflect.ZeroValue`.
---
 assert/assertions.go      | 58 +++++++++------------------------------
 assert/assertions_test.go | 15 ++++++++++
 2 files changed, 28 insertions(+), 45 deletions(-)

diff --git a/assert/assertions.go b/assert/assertions.go
index 8259050..4da8b8d 100644
--- a/assert/assertions.go
+++ b/assert/assertions.go
@@ -414,64 +414,32 @@ func Nil(t TestingT, object interface{}, msgAndArgs ...interface{}) bool {
 	return Fail(t, fmt.Sprintf("Expected nil, but got: %#v", object), msgAndArgs...)
 }
 
-var numericZeros = []interface{}{
-	int(0),
-	int8(0),
-	int16(0),
-	int32(0),
-	int64(0),
-	uint(0),
-	uint8(0),
-	uint16(0),
-	uint32(0),
-	uint64(0),
-	float32(0),
-	float64(0),
-}
-
 // isEmpty gets whether the specified object is considered empty or not.
 func isEmpty(object interface{}) bool {
 
+	// get nil case out of the way
 	if object == nil {
 		return true
-	} else if object == "" {
-		return true
-	} else if object == false {
-		return true
-	}
-
-	for _, v := range numericZeros {
-		if object == v {
-			return true
-		}
 	}
 
 	objValue := reflect.ValueOf(object)
 
 	switch objValue.Kind() {
-	case reflect.Array, reflect.Chan, reflect.Map, reflect.Slice, reflect.String:
-		{
-			return (objValue.Len() == 0)
-		}
-	case reflect.Struct:
-		switch object.(type) {
-		case time.Time:
-			return object.(time.Time).IsZero()
-		}
+	// collection types are empty when they have no element
+	case reflect.Array, reflect.Chan, reflect.Map, reflect.Slice:
+		return objValue.Len() == 0
+	// pointers are empty if nil or if the value they point to is empty
 	case reflect.Ptr:
-		{
-			if objValue.IsNil() {
-				return true
-			}
-			switch object.(type) {
-			case *time.Time:
-				return object.(*time.Time).IsZero()
-			default:
-				return false
-			}
+		if objValue.IsNil() {
+			return true
 		}
+		deref := objValue.Elem().Interface()
+		return isEmpty(deref)
+	// for all other types, compare against the zero value
+	default:
+		zero := reflect.Zero(objValue.Type())
+		return reflect.DeepEqual(object, zero.Interface())
 	}
-	return false
 }
 
 // Empty asserts that the specified object is empty.  I.e. nil, "", false, 0 or either
diff --git a/assert/assertions_test.go b/assert/assertions_test.go
index bb2b59f..987a9a6 100644
--- a/assert/assertions_test.go
+++ b/assert/assertions_test.go
@@ -806,6 +806,15 @@ func TestEmpty(t *testing.T) {
 	var tiNP time.Time
 	var s *string
 	var f *os.File
+	sP := &s
+	x := 1
+	xP := &x
+
+	type TString string
+	type TStruct struct {
+		x int
+		s []int
+	}
 
 	True(t, Empty(mockT, ""), "Empty string is empty")
 	True(t, Empty(mockT, nil), "Nil is empty")
@@ -817,6 +826,9 @@ func TestEmpty(t *testing.T) {
 	True(t, Empty(mockT, f), "Nil os.File pointer is empty")
 	True(t, Empty(mockT, tiP), "Nil time.Time pointer is empty")
 	True(t, Empty(mockT, tiNP), "time.Time is empty")
+	True(t, Empty(mockT, TStruct{}), "struct with zero values is empty")
+	True(t, Empty(mockT, TString("")), "empty aliased string is empty")
+	True(t, Empty(mockT, sP), "ptr to nil value is empty")
 
 	False(t, Empty(mockT, "something"), "Non Empty string is not empty")
 	False(t, Empty(mockT, errors.New("something")), "Non nil object is not empty")
@@ -824,6 +836,9 @@ func TestEmpty(t *testing.T) {
 	False(t, Empty(mockT, 1), "Non-zero int value is not empty")
 	False(t, Empty(mockT, true), "True value is not empty")
 	False(t, Empty(mockT, chWithValue), "Channel with values is not empty")
+	False(t, Empty(mockT, TStruct{x: 1}), "struct with initialized values is empty")
+	False(t, Empty(mockT, TString("abc")), "non-empty aliased string is empty")
+	False(t, Empty(mockT, xP), "ptr to non-nil value is not empty")
 }
 
 func TestNotEmpty(t *testing.T) {