Update tests a little bit and add comment

encode.go

@@ -657,6 +657,12 @@ func (enc *Encoder) isEmpty(rv reflect.Value) bool {
 		if rv.Type().Comparable() {
 			return reflect.Zero(rv.Type()).Interface() == rv.Interface()
 		}
+		// Need to also check if all the fields are empty, otherwise something
+		// like this with uncomparable types will always return true:
+		//
+		//   type a struct{ field b }
+		//   type b struct{ s []string }
+		//   s := a{field: b{s: []string{"AAA"}}}
 		for i := 0; i < rv.NumField(); i++ {
 			if !enc.isEmpty(rv.Field(i)) {
 				return false

encode_test.go

@@ -181,7 +181,7 @@ func TestEncodeOmitEmptyStruct(t *testing.T) {
 	}
 }
 
-func TestEncodeWithOmitEmpty(t *testing.T) {
+func TestEncodeOmitEmpty(t *testing.T) {
 	type compareable struct {
 		Bool bool `toml:"bool,omitempty"`
 	}
@@ -245,7 +245,7 @@ time = 1985-06-18T15:16:17Z
 		v, expected, nil)
 }
 
-func TestEncodeWithOmitZero(t *testing.T) {
+func TestEncodeOmitZero(t *testing.T) {
 	type simple struct {
 		Number   int     `toml:"number,omitzero"`
 		Real     float64 `toml:"real,omitzero"`
@@ -267,7 +267,7 @@ unsigned = 5
 	encodeExpected(t, "simple with omitzero, non-zero", value, expected, nil)
 }
 
-func TestEncodeOmitemptyWithEmptyName(t *testing.T) {
+func TestEncodeOmitemptyEmptyName(t *testing.T) {
 	type simple struct {
 		S []int `toml:",omitempty"`
 	}
@@ -1187,7 +1187,9 @@ func encodeExpected(t *testing.T, label string, val interface{}, want string, wa
 		have := strings.TrimSpace(buf.String())
 		want = strings.TrimSpace(want)
 		if want != have {
-			t.Errorf("\nhave:\n%s\nwant:\n%s\n", have, want)
+			t.Errorf("\nhave:\n%s\nwant:\n%s\n",
+				"\t"+strings.ReplaceAll(have, "\n", "\n\t"),
+				"\t"+strings.ReplaceAll(want, "\n", "\n\t"))
 		}
 	})
 }