chore: add test to verify allowable data layouts

Ref: https://github.com/ipld/specs/pull/297

pb/compat_test.go

+package merkledag_pb
+
+// mirrored in JavaScript @ https://github.com/ipld/js-dag-pb/blob/master/test/test-compat.js
+
+import (
+	"encoding/hex"
+	"encoding/json"
+	"testing"
+)
+
+var dataZero []byte = make([]byte, 0)
+var dataSome []byte = []byte{0, 1, 2, 3, 4}
+var cidBytes []byte = []byte{1, 85, 0, 5, 0, 1, 2, 3, 4}
+var zeroName string = ""
+var someName string = "some name"
+var zeroTsize uint64 = 0
+var someTsize uint64 = 1010
+var largeTsize uint64 = 9007199254740991 // JavaScript Number.MAX_SAFE_INTEGER
+
+type testCase struct {
+	name          string
+	node          *PBNode
+	expectedBytes string
+	expectedForm  string
+}
+
+var testCases = []testCase{
+	{
+		name:          "empty",
+		node:          &PBNode{},
+		expectedBytes: "",
+		expectedForm:  "{}",
+	},
+	{
+		name:          "Data zero",
+		node:          &PBNode{Data: dataZero},
+		expectedBytes: "0a00",
+		expectedForm: `{
+	"Data": ""
+}`,
+	},
+	{
+		name:          "Data some",
+		node:          &PBNode{Data: dataSome},
+		expectedBytes: "0a050001020304",
+		expectedForm: `{
+	"Data": "0001020304"
+}`,
+	},
+	{
+		name:          "Links zero",
+		node:          &PBNode{Links: make([]*PBLink, 0)},
+		expectedBytes: "",
+		expectedForm:  "{}",
+	},
+	{
+		name:          "Data some Links zero",
+		node:          &PBNode{Data: dataSome, Links: make([]*PBLink, 0)},
+		expectedBytes: "0a050001020304",
+		expectedForm: `{
+	"Data": "0001020304"
+}`,
+	},
+	{
+		name:          "Links empty",
+		node:          &PBNode{Links: []*PBLink{{}}},
+		expectedBytes: "1200",
+		expectedForm: `{
+	"Links": [
+		{}
+	]
+}`,
+	},
+	{
+		name:          "Data some Links empty",
+		node:          &PBNode{Data: dataSome, Links: []*PBLink{{}}},
+		expectedBytes: "12000a050001020304",
+		expectedForm: `{
+	"Data": "0001020304",
+	"Links": [
+		{}
+	]
+}`,
+	},
+	{
+		name:          "Links Hash zero",
+		node:          &PBNode{Links: []*PBLink{{Hash: dataZero}}},
+		expectedBytes: "12020a00",
+		expectedForm: `{
+	"Links": [
+		{
+			"Hash": ""
+		}
+	]
+}`,
+	},
+	{
+		name:          "Links Hash some",
+		node:          &PBNode{Links: []*PBLink{{Hash: cidBytes}}},
+		expectedBytes: "120b0a09015500050001020304",
+		expectedForm: `{
+	"Links": [
+		{
+			"Hash": "015500050001020304"
+		}
+	]
+}`,
+	},
+	{
+		name:          "Links Name zero",
+		node:          &PBNode{Links: []*PBLink{{Name: &zeroName}}},
+		expectedBytes: "12021200",
+		expectedForm: `{
+	"Links": [
+		{
+			"Name": ""
+		}
+	]
+}`,
+	},
+	{
+		name:          "Links Hash some Name zero",
+		node:          &PBNode{Links: []*PBLink{{Hash: cidBytes, Name: &zeroName}}},
+		expectedBytes: "120d0a090155000500010203041200",
+		expectedForm: `{
+	"Links": [
+		{
+			"Hash": "015500050001020304",
+			"Name": ""
+		}
+	]
+}`,
+	},
+	{
+		name:          "Links Name some",
+		node:          &PBNode{Links: []*PBLink{{Name: &someName}}},
+		expectedBytes: "120b1209736f6d65206e616d65",
+		expectedForm: `{
+	"Links": [
+		{
+			"Name": "some name"
+		}
+	]
+}`,
+	},
+	{
+		name:          "Links Hash some Name some",
+		node:          &PBNode{Links: []*PBLink{{Hash: cidBytes, Name: &someName}}},
+		expectedBytes: "12160a090155000500010203041209736f6d65206e616d65",
+		expectedForm: `{
+	"Links": [
+		{
+			"Hash": "015500050001020304",
+			"Name": "some name"
+		}
+	]
+}`,
+	},
+	{
+		name:          "Links Tsize zero",
+		node:          &PBNode{Links: []*PBLink{{Tsize: &zeroTsize}}},
+		expectedBytes: "12021800",
+		expectedForm: `{
+	"Links": [
+		{
+			"Tsize": 0
+		}
+	]
+}`,
+	},
+	{
+		name:          "Links Hash some Tsize zero",
+		node:          &PBNode{Links: []*PBLink{{Hash: cidBytes, Tsize: &zeroTsize}}},
+		expectedBytes: "120d0a090155000500010203041800",
+		expectedForm: `{
+	"Links": [
+		{
+			"Hash": "015500050001020304",
+			"Tsize": 0
+		}
+	]
+}`,
+	},
+	{
+		name:          "Links Tsize some",
+		node:          &PBNode{Links: []*PBLink{{Tsize: &someTsize}}},
+		expectedBytes: "120318f207",
+		expectedForm: `{
+	"Links": [
+		{
+			"Tsize": 1010
+		}
+	]
+}`,
+	},
+	{
+		name:          "Links Hash some Tsize some",
+		node:          &PBNode{Links: []*PBLink{{Hash: cidBytes, Tsize: &largeTsize}}},
+		expectedBytes: "12140a0901550005000102030418ffffffffffffff0f",
+		expectedForm: `{
+	"Links": [
+		{
+			"Hash": "015500050001020304",
+			"Tsize": 9007199254740991
+		}
+	]
+}`,
+	},
+}
+
+func TestCompat(t *testing.T) {
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			verifyRoundTrip(t, tc)
+		})
+	}
+}
+
+func verifyRoundTrip(t *testing.T, tc testCase) {
+	actualBytes, actualForm, err := nodeRoundTripToString(t, tc.node)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if actualBytes != tc.expectedBytes {
+		t.Logf(
+			"Expected bytes: [%v]\nGot: [%v]\n",
+			tc.expectedBytes,
+			actualBytes)
+		t.Error("Did not match")
+	}
+
+	if actualForm != tc.expectedForm {
+		t.Logf(
+			"Expected form: [%v]\nGot: [%v]\n",
+			tc.expectedForm,
+			actualForm)
+		t.Error("Did not match")
+	}
+}
+
+func nodeRoundTripToString(t *testing.T, n *PBNode) (string, string, error) {
+	bytes, err := n.Marshal()
+	if err != nil {
+		return "", "", err
+	}
+	t.Logf("[%v]\n", hex.EncodeToString(bytes))
+	rt := new(PBNode)
+	if err := rt.Unmarshal(bytes); err != nil {
+		return "", "", err
+	}
+	str, err := json.MarshalIndent(cleanPBNode(t, rt), "", "\t")
+	if err != nil {
+		return "", "", err
+	}
+	return hex.EncodeToString(bytes), string(str), nil
+}
+
+// convert a PBLink into a map for clean JSON marshalling
+func cleanPBLink(t *testing.T, link *PBLink) map[string]interface{} {
+	if link == nil {
+		return nil
+	}
+	// this would be a bad pb decode
+	if link.XXX_unrecognized != nil {
+		t.Fatal("Got unexpected XXX_unrecognized")
+	}
+	nl := make(map[string]interface{})
+	if link.Hash != nil {
+		nl["Hash"] = hex.EncodeToString(link.Hash)
+	}
+	if link.Name != nil {
+		nl["Name"] = link.Name
+	}
+	if link.Tsize != nil {
+		nl["Tsize"] = link.Tsize
+	}
+	return nl
+}
+
+// convert a PBNode into a map for clean JSON marshalling
+func cleanPBNode(t *testing.T, node *PBNode) map[string]interface{} {
+	// this would be a bad pb decode
+	if node.XXX_unrecognized != nil {
+		t.Fatal("Got unexpected XXX_unrecognized")
+	}
+	nn := make(map[string]interface{})
+	if node.Data != nil {
+		nn["Data"] = hex.EncodeToString(node.Data)
+	}
+	if node.Links != nil {
+		links := make([]map[string]interface{}, len(node.Links))
+		for i, l := range node.Links {
+			links[i] = cleanPBLink(t, l)
+		}
+		nn["Links"] = links
+	}
+	return nn
+}