property.explicit
    }

    def "can add to explicit value with append"() {
        given:
        property.set([])
        property.appendAll(Providers.of(["1", "2"]))
        property.appendAll(Providers.of(["3", "4"]))

        expect:
        assertValueIs toImmutable(["1", "2", "3", "4"])
        property.explicit
    }

		if z.ObjectV1 == nil {
			o = msgp.AppendNil(o)
		} else {
			o, err = z.ObjectV1.MarshalMsg(o)
			if err != nil {
				err = msgp.WrapError(err, "ObjectV1")
				return
			}
		}
	}
	if (zb0001Mask & 0x4) == 0 { // if not omitted
		// string "V2Obj"
		o = append(o, 0xa5, 0x56, 0x32, 0x4f, 0x62, 0x6a)
		if z.ObjectV2 == nil {
			o = msgp.AppendNil(o)
		} else {

	// string "lt"
	o = append(o, 0xa2, 0x6c, 0x74)
	if z.XferRateLrg == nil {
		o = msgp.AppendNil(o)
	} else {
		o, err = z.XferRateLrg.MarshalMsg(o)
		if err != nil {
			err = msgp.WrapError(err, "XferRateLrg")
			return
		}
	}
	// string "st"
	o = append(o, 0xa2, 0x73, 0x74)
	if z.XferRateSml == nil {
		o = msgp.AppendNil(o)
	} else {
		o, err = z.XferRateSml.MarshalMsg(o)
		if err != nil {

	}
}

func TestAppendln(t *testing.T) {
	b := make([]byte, 100)
	b = b[:copy(b, hello)]
	got := Appendln(b, "world,", 23)
	if string(got) != appendResult+"\n" {
		t.Fatalf("Appendln returns %q not %q", got, appendResult+"\n")
	}
	if &b[0] != &got[0] {
		t.Fatalf("Appendln allocated a new slice")
	}

	o = msgp.AppendInt64(o, z.Size)
	// string "ActualSize"
	o = append(o, 0xaa, 0x41, 0x63, 0x74, 0x75, 0x61, 0x6c, 0x53, 0x69, 0x7a, 0x65)
	if z.ActualSize == nil {
		o = msgp.AppendNil(o)
	} else {
		o = msgp.AppendInt64(o, *z.ActualSize)
	}
	// string "IsDir"
	o = append(o, 0xa5, 0x49, 0x73, 0x44, 0x69, 0x72)
	o = msgp.AppendBool(o, z.IsDir)
	// string "ETag"