chore(bindnode): add test for sub-node unwrapping

Closes: #339

I can't repro the error in 339, so I'm adding this test and will close the issue

node/bindnode/api_test.go

@@ -0,0 +1,125 @@
+package bindnode_test
+
+import (
+	"encoding/hex"
+	"testing"
+
+	qt "github.com/frankban/quicktest"
+	"github.com/ipld/go-ipld-prime"
+	"github.com/ipld/go-ipld-prime/codec/dagcbor"
+	"github.com/ipld/go-ipld-prime/datamodel"
+	"github.com/ipld/go-ipld-prime/node/bindnode"
+)
+
+func TestSubNodeUnwrap(t *testing.T) {
+	type F struct {
+		F bool
+	}
+	type B struct {
+		B int
+	}
+	type A struct {
+		A string
+	}
+	type S struct {
+		F F
+		B B
+		A *A
+	}
+
+	schema := `
+		type F struct {
+			F Bool
+		} representation tuple
+		type B struct {
+			B Int
+		} representation tuple
+		type A struct {
+			A String
+		} representation tuple
+		type S struct {
+			F F
+			B B
+			A optional A
+		} representation tuple
+	`
+
+	encodedHex := "8381f581186581624141" // [[true],[101],["AA"]]
+	expected := S{
+		F: F{true},
+		B: B{101},
+		A: &A{"AA"},
+	}
+
+	typeSystem, err := ipld.LoadSchemaBytes([]byte(schema))
+	qt.Assert(t, err, qt.IsNil)
+	schemaType := typeSystem.TypeByName("S")
+
+	verifyMap := func(node datamodel.Node) {
+		mi := node.MapIterator()
+
+		key, value, err := mi.Next()
+		qt.Assert(t, err, qt.IsNil)
+
+		str, err := key.AsString()
+		qt.Assert(t, err, qt.IsNil)
+		qt.Assert(t, str, qt.Equals, "F")
+
+		typ := bindnode.Unwrap(value)
+		instF, ok := typ.(*F)
+		qt.Assert(t, ok, qt.IsTrue)
+		qt.Assert(t, *instF, qt.Equals, F{true})
+
+		key, value, err = mi.Next()
+		qt.Assert(t, err, qt.IsNil)
+
+		str, err = key.AsString()
+		qt.Assert(t, err, qt.IsNil)
+		qt.Assert(t, str, qt.Equals, "B")
+
+		typ = bindnode.Unwrap(value)
+		instB, ok := typ.(*B)
+		qt.Assert(t, ok, qt.IsTrue)
+		qt.Assert(t, *instB, qt.Equals, B{101})
+
+		key, value, err = mi.Next()
+		qt.Assert(t, err, qt.IsNil)
+
+		str, err = key.AsString()
+		qt.Assert(t, err, qt.IsNil)
+		qt.Assert(t, str, qt.Equals, "A")
+
+		typ = bindnode.Unwrap(value)
+		instA, ok := typ.(*A)
+		qt.Assert(t, ok, qt.IsTrue)
+		qt.Assert(t, *instA, qt.Equals, A{"AA"})
+	}
+
+	t.Run("decode", func(t *testing.T) {
+		encoded, _ := hex.DecodeString(encodedHex)
+
+		proto := bindnode.Prototype(&S{}, schemaType)
+
+		node, err := ipld.DecodeUsingPrototype([]byte(encoded), dagcbor.Decode, proto)
+		qt.Assert(t, err, qt.IsNil)
+
+		typ := bindnode.Unwrap(node)
+		instS, ok := typ.(*S)
+		qt.Assert(t, ok, qt.IsTrue)
+
+		qt.Assert(t, *instS, qt.DeepEquals, expected)
+
+		verifyMap(node)
+	})
+
+	t.Run("encode", func(t *testing.T) {
+		node := bindnode.Wrap(&expected, schemaType)
+
+		byts, err := ipld.Encode(node, dagcbor.Encode)
+		qt.Assert(t, err, qt.IsNil)
+
+		qt.Assert(t, hex.EncodeToString(byts), qt.Equals, encodedHex)
+
+		verifyMap(node)
+	})
+}